1. if(fp = fopen(\”dfas\”,\”r\”) == NULL), what is the value of fp
a. NULL b. 0 c. 1 d. 0 or 1
2. #define sqr(x) x*x, what is value of j if j = 2 * sqr(3 + 4)
3. #define FILENAME(extension) test_##extension, how will it print FILENAME(back)
a. test_back b. test_#back c. test_##back d. ??
4. char *p = \”hello world\” p[0] = \’H\’, what will be printf(\”%s\”, p);
a. Hello world b. hello world c. H d. compile error
5. int fun(), how do u define pointer to this function ??
6. what is meant by int (* xyz)[13]
7. what is true from
a. base call reference is compatible with child class b. child class reference is compatible with base class c. no reference to class d. ??
8. class b class a { friend class b } then what is true
a. a can access all protected and public members in b b. b can access all protected and public members in a c. a can access all members of a d. b can access all members of b
HI, Zensar visited our college campus on 12/04/2007 and I m lucky to get through it. The selection procedure consist of 4 rounds. 1. Written(apti+eng+tech) 2. Technical written 3. Tech interview 4. HR interview
Written exam was not that tough. it is easy to clear if one is clear with basic things. the tech written in first round is a bit tough a btech person will definitely get nervous.
Then in the second round only tech exam was conducted. It consisted of 20 question and 20 mins. it is also a bit tough for btech guy. When the result was announced for this round i cant believe that i have cleared it. bcoz the test was real tough. Then came the interview
Sir: How can u change the booting process? Manish: by pressing f6.
Sir: What is the configuration of ur laptop? Manish: answered it perfectly as i m a hardware specialist.
Sir :What is diff. between C and C++? Manish: Defined it as good as possible. he was quite impressed i thnk.
Sir: What is exception handling? Manish: answered it with an example. ofcourse in a paper.
Then he came to DBMS Sir: What is normalization? and types? Manish: Defined it very nicely as it was my fav subject. he was impressed by the way I answered. I gave all the types of normalization with examples.
Sir: What is indexing? Manish: Also answered it. but i did not know much abt it.
Sir: Types of indexing? Manish: sorry sir i dont know.
Sir: What is polymorphism? Manish: Described it by real life example. again he impressed and said very good.
At last he asked me. Do u have any question for me?
I asked two question abt company. the interview lasted for 30 mins. results were declared soon and i was thru.
HR interview Mam: Have u taken ur lunch as the interview was after lunch? Manish:I said no bcoz i was eagerly waiting for my interview and cant feel my hunger.
Mam:Tell me abt urself? Manish: Described
Mam: How many members in ur family? Manish:Answered
Mam: What r the good qualities ur frnd find in u? Manish: I said hard working, loyalty, truthfulness
Mam: In which area u wud like to improve urself? Manish:I said i wud like to improve my comm skill.
Mam: What r u doing for that? Manish:I impressed her by saying people do reading, mirror speaking etc but i improve mine by talking to people like u.
Mam: What r ur achievements? Manish: Told every achievements in life small or big.
then she asked 1 ques from my extra curricular activity. to describe a event in a competition. while answering I used a Hindi word and she laughed and I too.
Which type of people do u like? I said extrover.
she said why? Then a long discussin continues.
At last she gave me an essay to write on offshoring within 5 mins. This interviev was also for 30 mins. At last she said wait for result. I thank and came out. And finally when the result was declared my name was there.
I attended interview for Zensar Technologies at Holy Mary College S R Nagar Hyderabad on 27 April 2007
First there was written test. It had 4 sections: English, Mathematics, Analytical and Technical 20 min were given for each paper. Except for maths all section were very easy. There were no -ve markings. out of 180 students only 20 were short listed for the 2nd round by gods grace I was one among them
2nd round was technical he asked me around 30-35 question mostly on C++ some from Unix and RDBMS.
1) Written it consist of 4 sections, each section has around 20 to 25 questns n u wud gt 20 to 22 min to solve. first section is english :- there were fiil in the blanks, find correct heading for givn passage,reading passage, synonyms,opposites,grammar. this section is little tough bt if ur english is good then u can clear easily.
2) Aptitude very esy questions on profit&loss,percentages,areas, volumes,time n work,height and distances,series,algebra u shud hav gud speed questions are vry simple. coz my apti is nt vry strong still it was easy fr me.
3) Logic puzzles from verbal rs aggarwal, coding, series of alphabets, jumbled sentences, to find correct sequences from given sentences, all in all vey easy section jst need gud speed.
4) Technical I foun it little tough n lengthy bt pepl with gud programmin skills will find it easy there were c, dbms, networkin. mostly questions from c output questions around 10.
At last i wud like to suggest u that wn u gt ur paper start from first section then speed up as they will give seperate time fr each section. so wn u r warnd to turn to nxt section before 5 min thn dnt solve lft out questns instd check the probability of choices that are repeatin n mark those choices in remanin time in each section. no negative markin so good luck for written exams.
Next comes technical inrtv my intervr was vry good. he creatd good envirnmnt. i gave my intervw at 9 in evenin. he askd abt my skils intrst.n ask acordingly. i told him abt networkin watevr he askd as this is my area of intrest. he askd me abt google os, cisco os, as i hav done CCNA from cisco. most imp thin they will surely ask abt data structures, linklist codes, daa so be through with that. my tecnical was avg.
Last was HR this lady was vry frenly. my communication skills r vry good so i was confidnt in this round, they chekd our patience by takin intrvw at 12 in night, chekd +ve attitude, ability to delivr uncr pressure. well she was really impressd by my participation in diffrnt activities n saw a team attitude. so she told me sleep nicely witht ny tension.
This site has helpd me a lot coz i was also deprresd n thot i wud nevr gt palcd bt see i gt placmnt in prefinal year so dnt loose hope God will give success to evryone. jst have good speed n confidence in u thn world is waitin fr u to give good opportunities.
1. Aptitute test: (Had 4 sections – english, maths, aptitude – logical reasoning and technical – c, c++, dbms, etc.
2.Technical Interview (questions like tell me about yourself and Based on project, C, C++, DBMS, DS, Software Engineering etc. )
3. HR interview (questions like tell me about yourself, about family background, tell me 3 things you are looking for in a company, are you comfortable to move to Pune, etc.) 4.Essay writing (Based on hobbies, current affaires, etc my topic was ?INDIA IN 2020″)
I waited for 9 Hrs for my interviews as they took both technical and HR interviews irrespective of the performance of the candidates. Be confident and keep smiling?
First there is the written aptitude part. Believe me, its just like other zensar written multiple choice questions. See the sample papers here for the written part. Here are the technical written test questions with the hr & tech interview complete questions.
Zensar Technical Written Test Questions:
1)which is the fastest: FTP, TELNET ,TCP, etc.
2)output: main(){ int x=20 ,y=35; x= x++ + y++; y = ++x + ++y; printf(?%d %d?,x,y); } (this c program code is provided and you have to find out the output. There are other c language programming skills questions like below.)
3)char *p[]=?rachit and devender?; printf(?%C?,++(p[4]));
4)const char *p[]=?abhishek and Ankur?;
char k=?a?;
p[1]=k;
printf(?%s?,p);
5)main(){
extern int i;
i=5;
printf(?%d?,i);
}
6) main(){ int i,j=2;
if(i%j !=0)
j=5;
printf(?%d?,j);
}
For what values if i the output will be 5 : options 1)when i is even 2) odd 3)prime 4) fro all 7)complexity of merge sort .?
8)which sorting also will use to sort {1,2,3,4,5} ?
9)which cpu register holds the address of next instruction?
12) we cant typedef (i) pointers (ii) function (iii) double (iv) I and II both above are some of the question which are been asked in the 4th section of the Aptitude test.
After 30 minutes, result was declared, 5 candidates were selected.
1) What is pointer to a function? 2) Explain the working of pointer to a function 3) Difference between char const *p , const char *p ,const * char p, const char * const p 4) What Is FILE *fp 5) Write a program to print a file from the last . 6) Write a program to encrypt the file
7) What is abstraction What is run time polymorphism 9) What is register storage class? If a variable is declared as register then is it compulsory that it will be of storage type register? 10) What is interface in java? 11) What is implementation?
12) Why java doesn?t support multiple inheritance? 13) Is c++ is pure object oriented? 14) Why we need new operator in java at the time of object declaration and why not in c++?
15) Write a program to implement virtual functions. 16) What is the difference between file and database storage ? 17) Difference between hierarchical data model and network data model ? 18) What are the 12 codd?s rule ? 19) Gave me a table and asked me to normalize it up to 3 nf . 20) Difference between BCNF and 4 nf ? 21) Difference between conflict and view serialzability 22) What is batch operating system ? 23) Difference between multiprogramming and multitasking ? 24) What are different types of scheduler ? explain short term scheduler ? 25) What are different scheduling algorithms ?
26) What is a system call? 27) Monitors and Semaphores ? 28) What are different CPU registers ? 29) Object oriented model , Component Assembly model and Waterfall model ? compare them ? 30) Difference between OSI and TCP/IP? 31) X.25 ?
1) Describe Yourself as a person ? 2) Say something about dream. 3) Which is your dream company ?
4) Then why zensar?
5)Where do you see yourself after 5 years?
Finally I got selected. Thank god.
So this was all. The full zensar placement test paper – multiple choice written test technical questions and the technical hr interview questions.
See more Zensar technologies india latest and previous placement exam papers – fully detailed zensar placement test papers with answers, solutions and hints. Download free mnc it companies latest 2008 placement papers. See more papers - helpful candidate experiences and all important topics.
My name is VINAY CHAUHAN i m doing my B.E. (Com. Sci.) from GLOBAL INST. OF TECHNOLOGY, JAIPUR. I attended d centralized campus organized by ZENSAR TECHNOLOGIES, PUNE. campus was held at poornima college of engineering. Here i m describing the selection prcedure– candidates having 60% in 10th n 12th and B.E. aggregate 70% with branches CS, IT, EC were only allowed to appear in d campus drive.
First of all they conducted aptitude test, contains these sections. 1. ENGLISH ABILITY. 2. QUANTITATIVE APTI. 3. LOGICAL REASONING. 4. TECHNICAL SKILLS.
These sections in paper contains 80 questions and duration was 80 mins. We have to do each section in 20 minutes. We coudnt move to next section before 20 mins. and once a section is completed we coudn’t go back.there was sectional cutoff. some of the sample questions which i remember are –
A) English ability –
Q1. which is suitable combination similar to – pesticide : crop :: antiseptic: ? a) wound b) clothing c) bandage d) bleeding.
Q2. It is a long time………….i saw my friend who lives……………his parents………..he neighbouring town. a) when ; at ; of b) since ; with ; in. c) when ; for ; in d) since ; for ; of. and other questions of selecting suitable words and also 3 questions based on one small passage. it was very easy one and in fact d easiest section was english section only.
B) Quantitative aptitude–
Q1. if ratio of milk and water in one container is 3:5 and in another is 1:2 they mixed togeher then what is ratio of milk and water ?
Q2. dimension of a room is 5*8 meters. room floor is covered by carpet by leaving space 4cm from walls. if carpet is 18rs. per meter then total cost?
Q3. find out d odd one in d series : a)9 b)121 c)361 d)881. Ans. d)881 since it is not a perfect square.
It also contains questions related to tabulaion, distance and time, work percentage, profit and loss. R. S. AGGARWAL is more than sufficient. it is time consuming part be fast otherwise u will not be able to attempt all the questions.
C) Logical reasoning –
For me dis section was tough coz it really consumed time n it was not possible to attempt all d questions in mere 20 minutes. Although i tried my level best n i was sure i will cross d cut off of this section. so guys b fast 4 dis section. simple q based on venn diagram and selection of suitable statement were also there refer R. S. AGGARWAL (verbal).
D) Technical skills –
This section was complete technical so be prepare. It contains C, C++, DBMS, RDBMS and general computer architecture. This is all about written test. 66 students were selected out of 600. I cleared dis round and then dey gave ppt to the selected candidates only. From my college only three cleared the written test. In ppt dey talked about company profile.
Here he asked me to show him my resume. Then he asked me about ORACLE. I strictly said no sir i m not good at Oracle because i havnt studied it yet. then he said ok which languages u have studied so far strictly mention all d languages which u have mentioned in ur resume i said C, C++, JAVA.
Q1) what is the difference between C and C++? Q2) what is object oriented programming? Q3) what is the difference between the class n objects? Q4) what was the need of classes? truly speaking i loved dis question then i described from the beginning mentioning the name of the person who invented C++ and all the things which were required to move to classes n object oriented concept.
Q5) what is encapsulation? always try to give precise n exact definitions with examples
Q6) what is abstraction? Q7) what is the need for abstraction? give some practical example? Q8) what is inheritence? Q9) give a real life example of inheritance? Q10) what is polymorphism? Q11) write a program for SWAPPING? main()
{ int a=5; int b=10; a=a+b; //a=15 b=a-b; //b=15-10=5 printf(“value of b is %d”,b); a=a-b; //a=15-5=10 printf(“value of a is %d”,a); }
Actually i did this program witout using temporary variable then he asked me is there any other method then i very smartly said yes sir v can also use a temporary variable.
Q12) what is jvm? Q13) what do u know about data base management system? Q14) what is rdbms? Q15) write a query to create a table? Q16) if v dont pass the fields name then vil d table b created? Q17) what is preprocessor? C Q18) what is the difference between compiler and interpreter? Q19) what is the command to make a file in dos? i said i was not able to recollect it now.
Q20) what are header files? Q21) what r the needs for header files? Q21) what is d difference between preprocessor directives n header files? Q22) what is the use of main in any program? Q23) when v make graphics in c++ then which header file v include?
Questions were very simple n was all basics a student from CS branch must know.
H.R. round-
Vinay: may i come in mam? HR: hi Vinay please come in
Vinay: may i have a seat mam? HR: Ya sure please sit.
HR: Ok Vinay take dis paper n now i vil give u 5 mins write something abot urself ur college ur branch n y u opted 4 dat branch n how do u see urself after 5 years 4rm now?
Vinay: I quickly finished the work in less than 2 mins.
HR: (Mam started readin it) Ok Vinay what do ur father do? Vinay: Mam my father is a govt. servant.
HR:How long has he been serving 4 his organization? Vinay: 27 years
HR: Oh dat is a very long time would u serve 4 an organisation 4 such a long time Vinay: I said mam it depends totally on d work environment n also if there is a kind of emotional bond b/w me n employees of the company.
HR: so u r a very emotional kind of person Vinay: yes mam i m a very emotional kind of person.
HR: Ok imagine u r a CEO of a company n one of ur friend who is emotionally attached to u asks u to leak the secrets of the company wud u do dat? Vinay: No mam the first priority is 4 the firm 4 which i m serving n no compromise on dat part.
HR: ok so u r emotional but not ethnically emotional. What kind of person r u? domestic or international? Vinay: I said domestic n justified wid my views.
HR: Next she asked traditional or modern? Vinay: I said traditional n gave the example of lalu prasad yadav (rail minister of india) being a traditional kind of person in speaking n living he is popular all over the world.
HR: she asked me really Vinay: Then i said mam he recently gave management classes to students 4rm HORWARD UNIV. Mam u must hav read in the news paper?
HR: she said yes i did. Ok what kind of animal do u like? n y? Vinay: I said ANT coz hard working, always moving towards its goal, n team work.
HR: I think u watch national geography channel a lot. Vinay: I said no mam i dont.
HR: Then what do u watch in ur TV set? Vinay: I said i dont get time to see TV.
HR: Then she asked me how do U manage ur time? Vinay: Mam after my college i use to give tuitions to school going children.
HR: U live in hostel or some where else? Vinay: I said my hometown is in udaipur bt i live here with my relatives.
HR: Ok Vinay thank u very much thank u mam it was pleasure talking to u. Vinay: same here.
she asked me 4 two photographs of mine.
Zensar is a company which takes both technical n hr interviews of all d candidates irrespective of the performance. Result came after 8 days to my college they selected only 13 out of 66 who cleared the apti n i was one of them. only thing i wud say to u is hard work is the only key to success because what i believe is dat luck is a loser’s excuse 4 winner’s position.
This was my fifth interview within a span of 2 months. n thank god this time i made it earlier companies were
So never lose hope n whenever u fail then jus think dere is something better 4 u in the store. have faith in GOD n no one can stop u 4rm reaping the success of ur dreams.
I am stud of (Dept.-IT, BIT, Kolkata) & I got in ZENSAR TECNOLOGIES through campus placement process.
The interview process was divided into three parts::- (1) Aptitude test (88 questions 80 minutes) (2) Technical Interview (3) HR Interview.
Some of our friends had technical and HR together, some had separately. I had my technical & Hr together. Total 91 students had cleared there apti & finally 36 out of them were selected.
There were four sections::- (a) General English & verbal test, (b)Quantitative aptitude (c)Logical reasoning (d)Technical (mainly on C, dbms). [concentrate on R.S.Agarwal for quanti & the logical part.]
1. What are the types of OS, with examples? 2. Difference between Linux & Windows. 3. During multitasking, whether the jobs are executed parallely? Whether the WINDOWS OS is pre-emptive? http:/ 4. Is multitasking & multithreading are same or not? 5. Various versions of WINDOWS. 6. Latest Version of WINDOWS(Windows vista). 7. What do you know about Vista ? 8. What is SDLC & its steps? 9. How will you decide which language (whether c,java,etc..) is suitable for the development of a particular software? 10. Why java is platform independent? 11. Are the JVM for C & JVM for JAVA are different? 12. What are byte code & object code? 13. Difference between C & Java. 14. What is polymorphism & its types? 15. How overriding is done? 16. What is inheritance? 17. How error handling is done in Java? 18. Types of classes in Java. 19. Storage classes in C. 20. Types of function calls? 21. Call by reference & call by value.Which is better? 22. What are the types linklist? 23. Write a program to search a certain node in a linear linklist? 24. Write a program to find the length of a string in C?
25. Why Zensar? Your plans for the next 4 years with Zensar. 26. What are your achievements? 27. Which part of the powerpoint presentation did you like the most? 28. How many presentations have you seen before? 29. Why have you failed in the interviews which you had earlier? 30. How will you rate yourself out of 5 in the technical interview? 31. What do you think, your weakest part in technical interview? 32. Will you have any problem, if you are relocated out of kokata? 33. Do you have any questions for us?
I attended the open campus recruitment of Zensar held in H.C.E.T. Jabalpur. I wasn’t able to clear the written but I am posting this paper so that u can utilize my experience in cracking Zensar.
1) ENGLISH 2 questions on synonymns 1word was acrimonious & I don’t remember the other 1 2 ques. on antonymns like amorous some ques on grammar corrections & 1 RC very easy There were 21 ques & the time was 20 min. Friends if u have gud hold in English then u need not worry about this section.
3) Logical Reasoning 20 ques 20 min This was very easy. even without preparation u can solve atleast 8 to 10 ques. 2 ques. on DI pi chart 3 ques. from syllogisms 1 ques. on number series : 17,31,59,115,? (exact ques) ans 227 2-3 ques. on coding encoding 3 ques. on seating arrangements : a,b,c,d,e,f r to be arranged around a hexagon, a should be opposite of f, d should be between a & b bl ab la bla rest I don’t remember.
4) Technical 21 ques. in 20 min very easy ques. were basically from C, RDBMS, data com, computer architecture only a basic knowledge of C is required to crack this section.
Prepare well & try to attempt as many ques as u can as there is no negative marking. try to attempt atleast 14 ques in each section.
We have created a real-time video object tracking / shape recognition device, and a fun game library to demonstrate its abilities.
For our project, we wanted to push the video sampling and processing capabilities of the ATmega644 8-bit microcontroller. Using a high-speed analog-to-digital converter as an input device, we were able to sample a reasonably high-resolution grayscale image from a color camera’s video output. Using this grayscale image, we are able to track objects and recognize shapes that stood out from the background by a customizable threshold.
From this system, we created a game called Human Tetris to show the shape recognizition capabillity. In this game, players must contort their bodies into shapes displayed on screen in a given amount of time. To demonstrate the potential for our device to expand to a larger game library, we also implemented a port of Brick Breaker. This game shows off the object tracking capability, where players must physically interact with the bouncing ball to keep it on screen and break bricks.
High Level Design
Almost all major gaming consoles are moving to user input systems involving tracking all or part of a player’s body (see Nintendo Wii Remote, PlayStation Move, and XBox Project Natal). Our project setup is similar to Project Natal, which Microsoft claims to be a “controller-free gaming and entertainment experience”, using a single sensor device (with at least camera and microphone) placed by the TV. We have demonstrated the feasibility of a basic motion-controlled gaming system using low-cost parts.
The system is based off of an ATmega644 microcontroller with two peripherals: a high-speed flash analog-to-digital converter, and an onscreen display device for video overlay. With just 4 kilobytes of RAM and a 20MHz clock speed, the MCU needs these peripherals to take some of the load off of its processing capabilities. Since we wanted to provide a real-time camera feed on the display (like a “mirror” for the player), and since the ATmega644 is not fast enough to generate a full color NTSC signal, we decided early on that we would use a color video camera module which outputs an NTSC signal directly.
The system accepts a color NTSC video signal, filters out the DC component, and samples the video stream at real-time speed. This sample is stored as a grayscale image in the MCU’s memory which can be processed by the application. The onscreen display overlays shape information and game data for user interaction.
Based on this system, we have implemented a video arcade game called Human Tetris, based on a Japanese game show event. In the game, contestants are faced with an oncoming solid wall with a shape cutout. The players must fit through the shape, or else they are thrown back into a pool of slime. A few clips from the show are shown in the YouTube video below:
Our game displays a shape on the screen which the players must fit into within a short amount of time. If they succeed, they are faced with more difficult shapes and shorter amounts of time until they are inevitably “slimed”. The game provides the player with real-time feedback by displaying the video on the screen with the device’s interpretation of their shape.
Our project involves two standards: NTSC and SPI. NTSC is well-defined and is used as our input and output medium. SPI is more of an agreement than a standard, and our project uses it internally to the specifications of the microcontroller and on-screen display device.
Tetris is copyrighted and trademarked thoroughly, so attempts to turn this project into a product would have to be preceded by licensing talks or altering the aesthetics. “Human Tetris” is a commonly used description for the game show our game is based on, but the actual game play is not that of Tetris.
Hardware
Prototyping
Our finished product is neatly tucked onto a 2.5″ x 3.8″ custom printed circuit board, but for most of the design stage, we prototyped on an STK500, a solderless breadboard, and the ATmega644 custom target board. Our earliest prototyping simply involved working with the ATmega644 on the STK500, with the surface-mount peripherals soldered to breakout boards on a solderless breadboard, attached to the STK with long, loopy wires. We also used the large protoboards as an external power source to feed our substantial power requirements. Slowly, we weaned off our dependence on the STK and moved to using just the solderless breadboard and the target board, with an on-board power circuit. Once the PCB was set up, everything was contained
Design & Components
At the start, we decided in our high-level design that it was essential for the user to have real-time feedback of their position on the screen. This allows the player to correct their position on screen or move to an object. Since our microprocessor is not capable of outputting color NTSC, we decided to use a camera which outputs an NTSC signal directly. Then, we could split the signal for display and processing. We chose the CM-26N color video camera because it was moderately priced and simple to use: simply plug in power, and it outputs a video signal. It also has a few features we were not aware of when we bought it, such as auto-brightness. One thing that we did not realize until setting up the system was that a camera pointed at the player would not produce a “mirror” effect like desired; instead, if a player moves to the right, he will move left on the screen. To remedy this, we used a low-tech solution: we point the camera at a mirror to flip the image it sees and displays on the screen, so that the game feels more natural to the player.
The signal from the camera goes through an RC input filter which biases up the signal swing to about 0.5V to 2.0V. This is based on the MAX7456 datasheet’s “Typical Operating Circuit”, which specifies a 75 Ohm load resistor to ground and a 0.1uF input coupling capacitor. Originally we had intended to create two separate circuits for display and processing using current buffers, and a shift/gain op-amp for input into the analog-to-digital converter. However, it was simpler and worked just as well to use the same signal as an input to both devices; it did not produce any detrimental effects.
The signal from the camera went into the analog input of the TLC5540 flash ADC. Since this signal swung from about 0.5-2.0V, we set up a bottom reference voltage of 0V and a top reference voltage of 2.0V, using a combination of the ADC’s internal voltage divider and a parallel resistor. This provided a good level of resolution for our application. We set up a clock output from the MCU to go into the sampling clock port of the ADC, so that we could control the clock speed through software. The 8-bit parallel output from the ADC went to the 8 pins on the MCU’s port C. During prototyping, we experienced a lot of noise on these high-frequency digital signals, which produced some bad reads and unexpected behavior. The custom PCB brought these components must closer together with good traces between the two devices, which essentially eliminated all of these problems.
The MAX7456 on-screen display (OSD) was used as our primary output device, to overlay characters and data on top of the video signal going from the camera to the TV. The SPI interface between the MCU and the OSD allowed high-speed communication for user feedback. It also took a lot of processing demands off of our MCU, since we could just tell the OSD what to do over SPI quickly, and the OSD would take care of the video overlay and timing issues. The OSD also provided some incredibly useful synchronization pulses for vertical sync and horizontal sync in the NTSC signal. We used these outputs to tell our MCU when to sample the video. We had a lot of trouble during the prototyping stage with bad writes to the OSD, most likely due to noise in the high-frequency communication on the SPI wires connecting the devices. Similar to the case with the ADC, when these components were carefully placed on the custom PCB, all of these issues disappeared, and the SPI communication could be cranked up to several MHz.
While we were originally planning on using the ATmega644 MCU, we wanted to sample the part, and we could only get samples of the ATmega644PA. These microprocessors are virtually identical (the ‘P’ is a low-power version of the chip, and the ‘A’ represents a manufacturing change). Virtually none of the hardware or software needed to be changed to accommodate this new chip. We opted to run the chip at the maximum clock speed of 20MHz for highest performance, but this is still below the threshold for direct video capturing or generation, which is why we had to use the two peripherals. We were also limited to the 4K of RAM, which limited the amount of pixels from the sampled image we could store. Otherwise, the MCU acted a central hub for the entire circuit: everything was controlled by the MCU, and it implemented all of the game and user interface logic.
We determined that the current drawn by the total circuit was close to 0.6A (camera ~120mA, OSD ~430mA, flash ADC ~20mA, atmega644pa ~12mA), so we used a power adapter and created a power circuit that supplied up to 1 Amp of current. We used a 12V DC power supply, a 1A rectifier (1N4001), and a 5V voltage regulator (LM340T5). We also included a power switch to break the connection from the supply to the power circuit.
Our finished product contains an on-board power circuit with power switch, reset and user interface buttons, blinking LED heartbeat (with jumper to turn off), camera and program headers, exposed RX/TX ports for serial debugging, three surface mount chips (ADC, MCU, OSD), two crystals, several resistors and capacitors, a ground plane to reduce noise/interference, and an RCA jack for video output to a TV.
Custom PCB
About half way through the design stage, we realized that a custom PCB could be very beneficial to our project. After getting approval from Bruce Land, we decided that we would attempt to design and build a custom PCB after we had finalized our hardware design, budget and time permitting.
After we received and soldered components to the PCB, we found one small connection problem on the NTSC input circuit, which destroyed the signal. The resistor’s lead in the RC circuit had to be moved to the other side of the capacitor [corrected PCB design file in schematics]. After a bit more debugging, the PCB worked perfectly. It essentially eliminated all of the noise and other issues we were having with our hardware. There were no longer any bad reads from the ADC or bad writes to the OSD. Everything behaved as it was designed, despite the high frequency signals we were sending between components.
Software
Our software consists of several major sections, corresponding to various hardware pieces and the various tasks required to achieve our goal. The first thing we developed was the driver for the on-screen display device, since that would be our only real output. Then we worked on getting video signal input. With input and output functioning, we moved on to data processing. Once we had a handle on how many resources we had left (in terms of memory and cycles), we moved onto writing the logic for program flow. With a simple shape-tracking library now at hand, we fleshed out the test code into Human Tetris and added Brick Breaker as a quick demonstration of the shape-tracking code’s potential.
SPI Driver for On-screen Display
Talking to the MAX7456 On-Screen Display through the ATmega644′s Serial Peripheral Interface proved to be an interesting challenge. Thankfully, someone had written an open-source library for doing so based on the ATmega162 architecture. Porting that to run on the ATmega644 was just a matter of reading data sheets and swapping register values for macros. However, the open-source library was based on bit-banging. Since Bruce Land covered using the ATmega644′s hardware SPI in lecture, we upgraded our driver to use that. Writing to the SPI works very well, and works as fast or slow as we can set it. Unfortunately, we never got SPI reads to work and are not sure why. But since we only needed the MAX7456 for output and it has such a well-designed interface, this was not a problem. One way reading could have helped would have been to confirm writes, since noise was a major problem prior to using the PCB. To combat the noise, we just reset all configuration options right before every frame, and hoped for the best on transmitting the frame data.
Our first surprise lesson in writing all of the datasheet came when we tried flashing a complete set of new characters to the OSD’s EEPROM character memory. Hardware constraints limit this action to only 8 characters at once (per on-off cycle). Since our output goals involved using the OSD to display much more than text, we needed a better option than programming and booting it 32 times over every time we altered our OSD images. Hooking up the OSD’s reset line to an output that we could toggle allowed us to use one run of the microcontroller to program the entire character memory.
Custom characters themselves were a cinch thanks to the same person that wrote the open source SPI driver. There exists a web page (see references) that will take a PNG image of all 256 characters and return a C header file of character data ready to be used by the open source driver. Our only issue here was that for some reason having an array of PROGMEM array pointers caused all the data to land in the Data memory, which was way above our 4kB limit. Using a rather long function to load the character data on a per-character basis solved the problem.
Part of our need for custom characters came from one of the OSD’s limitations, it only displays 13 rows of 30 characters each in NTSC mode. Also each character pixel is either black, white, or transparent. But each character is 18×12, so NTSC “pixel” level display is still possible. We split each 18×12 character into a 3×2 grid of 6×6 sub-characters, giving us a 39 x 60 symbol screen resolution. 6 sub characters means 64 possible combinations of them, so we wrote makedots.m in Matlab to take a 6×6 pixel symbol and output all 64 combinations as an image ready to send to the character map conversion website. By keeping them in a clever order in PROGMEM, we could get our desired 18×12 output character by using 6 bit flags per character and then just adding the address of the blank to the sum. To get a 18×12 block from 6 pieces of 6×6 data, we just take the majority vote of the 6 pixels, with ties going to blanks.
NTSC Sampling
As one might imagine, getting a video signal into the ATmega644 proved to be quite a challenge. Talking to our flash ADC was rather trivial, since its only input from the micro controller was a clock. Things got less trivial when we realized the suggested clock minimum frequency was 5MHz, which is 1/4 of our own clock speed. We set up Timer 2 to control an output bit, so it could run independently of the CPU. Prior to using the PCB, we setteled for 1.25MHz as a balance between noise and temporal resolution. Once we had the PCB, running the ADC clock at 5MHz worked best.
NTSC signal behavior. [Stanford EE 281, Laboratory Assignment #4 "TV Paint". See References]
With the clock set up, we had an 8 bit digital version of NTSC flying at our MCU. If we tried to read it all in, we would be out of RAM in 400 microseconds. Down-sampling was a necessity. 39×60 pixels not only down-sampled nicely to the OSD, it took up just over half our RAM. So we can only hold one “frame” at a time. Loading 39×60 out of a 242×338 signal meant sampling roughly every 6th pixel in every 6th line of an NTSC frame. Lucky for us, our OSD not only output NTSC, it output the horizontal and vertical sync pulses. We connected those directly to the ATmega644′s hardware interrupts, so we could get fairly accurate responses to the start of every frame and the start of every line. The “porches” gave us time to context switch to the ISRs and do the book keeping necessary for down-sampling. 60 samples on a 51.5us line of data meant one sample every 0.85us, which is 17 cycles. To achieve this level of accuracy, we inserted NOPs into our C code until things lined up correctly. We also used microsecond delays and NOPs to center or reads along the visible data part of the horizontal line.
To get the sampling perfect, we needed something better than the imperfect display of our NTSC output. We connected up the UART and wrote a method to dump out a frame of data on to it. However, dumping a frame of data takes almost a minute, so we had to make it due so only after a button push. This made for excellent comparison of test images to read results, which were visualized using MATLAB. We also wrote a MATLAB function to read directly from the UART, which was sometimes more convenient. Viewing our raw data on the computer helped us notice when we had only a few pixels of either porch data or bad reads.
Input Filtering
A few pixels of bad reads would have been okay, but prior to using our PCB we had more than a few bad reads. There was substantial noise all over the circuit, and since we were mostly just moving data around, this was a big problem. We tried out several different approaches to filtering. First, we screened out all bad pixel reads and replaced them with the average of their neighbors. However, bad reads often occurred in clusters, so this did not work. Using a fixed gray value as a replacement worked better. Between down sampling and the noise, our output had a lot of flickering elements. Applying a simplified Gaussian Blur gave smoother results, but that went against our general goals of shape-matching. Averaging two frames of input together would have been great, but that would have required more RAM than we had. We tried out sampling more lines (so higher vertical resolution) and averaging on the fly, but the PCB arrived and squelched noise before we could get the timing right in that code.
Output Filtering
The PCB result was sharp and flawless, but the down-sampling effect was still causing an annoying flicker. Not wanting to have to slow down our game(s) just for the sake of flicker, we came up with a method of filtering our output based on our previous output, a moving average box filter of sorts. We still didn’t have the memory to duplicate even a 13×30 output frame, but by repeating characters across many addresses we could use the address itself to store information. Looking at the last two lines of our character set, you can see we increment the address when there is positive info and decrement it when there is negative info. By capping the ends (so as to not overflow or underflow), we can display a nice running average over time with minimal memory and cycle cost. Our increments and decrements are set to 3, so it takes less than 3 frames for white to black changes and it takes at least 3 positives or negatives in a row to create a noise blip.
To avoid output flicker from frequently updating the OSD, we don’t flush our output buffer to the OSD until the end of our main loop. Keeping this output buffer around is also what lets us do time-averaging of our output to avoid flicker. Another flicker that can appear is a nauseating collection of video signal artifacts when the OSD is displaying characters that are pixel level grids. For this reason our standard background is a loose 1 out of 4 pixels instead of a tight checkerboard pattern.
Timing
In order to run our games, we needed some sort of time base. Since we had a 20Mhz crystal and 20 is not a power of 2, we had to use Timer 1 to get a time base on the order of milliseconds. We settled on a 5ms time base as a balance between ISR executions and accuracy. That time base controls the game state and timers, but the main loop is actually triggered by the NTSC sync pulses. The vertical sync ISR activates the horizontal sync ISR for reading in a frame if a flag is set and the horizontal ISR sets the flag down when reading in a frame is complete. The main loop does the opposite, running when that flag is not set and raising it when finished. This way every time main executes it has fresh input. We run our tracking mode as fast as possible and our games at half that in order to make the OSD flicker less during gameplay.
We have 2 buttons for input, “toggle” and “enter”, which are sufficient for a menu system. We run a de-bouncing flag-raising state machine to get meaningful input from sampling them at around 30Hz. We run a heartbeat LED at one second per cycle, so we can tell if things are working fine or not. In addition to the heartbeat LED, we keep a “Game Timer” at a 5-millisecond time base for game play purposes. We also sample the on-board ADC at 1Hz to get specified black level, which can be set by a trimpot to tune the game(s) to different environments. This live tuning is a bit more useful than just viewing exact values from a UART frame dump and guessing at a good threshold for detection.
Menu and System State
Our menu allows users to choose between the three games and the tracking mode. One button is used as a toggle to go to the next option and the other button is used as enter to select an option. The menu is a simple state machine. Each frame it displays the title, our names, and all the options with the current selection highlighted.
The state of the system is another state machine with states for menu, each of the games, tracking mode, and a win/lose screen. Each “frame” through the main loop activates the code for the appropriate state. The initial warning message is displayed for a few seconds the first time the menu state is activated, which is when the system turns on.
Games
The game state machines are based on the 1 millisecond base of “Game Time”, and the logic is independent of the frame rate. This means we can speed up or slow down our frame rate as needed and not affect the game mechanics. The main state machine simply loads the input data from the video stream then calls out to game logic for each frame. In our game modes, we display the player’s body as a collection of 12×18 character sized blocks for aesthetic value and decreased noise, as opposed to the 6×6 dots used for tracking mode.
Our Human Tetris game does the following. Each shape is displayed for 5 seconds. It is loaded into memory once, then player is displayed each frame using the moving average code (described above) to preserve the shape information. Once the shape and player are in the output buffer, simply looping through that buffer tells us how many “blocks” of the player’s body are outside the shape. If more than a certain tolerance are outside, the player loses. If not, the game advances to the next shape until a victory screen is reached. The number of misses is only checked at the end of a shape’s time.
We implemented a rather nice content pipeline for the Human Tetris shapes. One can place an arbitrary amount of images in a directory, and then run the MATLAB script imgs2progmem to get out a C header file with a single array holding all the shape data in program memory. The only restrictions are the input images must be 39 x 60 and black and white. It should be noted that the shapes are effectively stored as a bit vector (1 bit per block) in the C file. This compresses each shape to a mere 293 bytes, so we could fit a lot in program memory. The artist should keep in mind that the game currently displays shapes and players on a 13×30 grid (via averaging), so care should be taken when drawing the 39×60 sized shapes.
To demonstrate the extensibility of our shape tracking code, we also implemented a few other games:
Our first additional game is Brick Breaker. The game world consists of bricks (3 characters wide), a bouncing ball, and the player’s “bar” which is represented by character-sized blocks as in Human Tetris. The ball is actually on a 39×60 grid and is displayed as such. The ball bounces indefinitely and consistently. If it falls off the bottom of the screen the player loses a life. If it strikes a brick it damages the brick. If a player destroys all the (breakable) bricks before losing, the player will advance to the next level.
We have also added the Whack-A-Mole game to our project. The mole is composed of 2 rows of 3 characters, giving it a 36×36 pixel footprint. The moles are randomly drawn and removed, loosely based on the current time. The player must get his/her block representation onscreen to collide with a mole in order to “whack” it. Doing so removes the mole from the screen and awards the player with points. When the game time expires, the player’s score and any remaining moles are visible.
Results
Speed and Accuracy
We can read in and display an image of 39×60 pixels at 30 frames per second. That is the meaningful maximum, since NTSC is actually only 30 frames per second of information. The signal runs at 60 frames per second, sending every other line every other frame. We only read on every other vertical sync to de-interlace the signal. Our output tends to flicker a little as a result of down-sampling (as opposed to averaging) the NTSC image data. There is currently a little streaking in the output where characters are shown due to noise in the OSD.
Tracking Demo
To demonstrate our speed and accuracy, we wrote a tracking demo that simply reads the NTSC signal and displays our full resolution output as fast as it can. In object tracking mode, we simply clear the output buffer, load in the input at 39×60 resolution, and display that. This demonstrates the accuracy and speed we were able to achieve.
At 30 frames per second, there is minimal lag on our interpretation of the image. We do not do any filtering in tracking mode. There is a little flicker along the edges due to our down-sampling method. This tracking mode proved very handing for general debugging and especially for getting the timing right for reading in an NTSC frame.
Game Safety and Usability
Anyone capable of movement can play the games in this project, and difficulty can be adjusted by adjusting one’s difference from the camera. In this way the game can be adjusted for players of various sizes. The game is also only looking for dark colors, so light colored materials can be used to exclude parts of the image. Brick breaker is a nice alternative to human Tetris for any physically disabled players that might stumble upon our game.
Conclusions
Results vs. Expectations
When we drafted our proposal, our vision of the finished product is very similar to the device we have created. Much of the same hardware devices and software techniques we planned on using ended up in our final design. The main hardware drawback we experienced was that the NTSC decoder we had original planned on using was too fast for our MCU. Instead we had to select and use an ADC which would run independently and we could choose when to sample. In effect, since we only cared about the black-and-white signal, this was all we needed to achieve the same sampling effect we had originally planned on.
We have exceeded our expectations in both spatial and temporal resolution. We originally hoped to just barely have enough resolution for a stick figure and to process the image once every few seconds. We currently have enough resolution to recognize each other in debug images and are processing it all many times a second.
Next time adding sound to the game would make it much more enjoyable (and potentially deepen game play).
Conforming to Standards
Our project uses standard NTSC input and therefore the camera could be swapped. It also produces standard NTSC output, so any device capable of displaying that can be used.
We also use SPI internally. This is not exactly a standard, which probably explains why we only have it working in one direction.
Intellectual Property
We used open source code licensed under GPL v2 used as basis for our OSD SPI driver. The GPLv2 states that any code linking against the GPL v2 code must also be within the GPLv2 license. This probably limits our ability to monetize the project as it stands, since ownership cannot be claimed on GPL v2 code.
Tetris and its artwork are copyrighted and trademarked, so at the least we would have to change the name and some artwork in order to capitalize on our design. Brick Breaker is a new name for Breakout, and there is likely some ownership on the original design but currently many knock-offs exist.
Breakout is an arcade game developed by Atari, Inc and introduced on May 13, 1976 [Wikipedia].
The games we implemented are someone else’s IP. Our driver is GPL-licensed, so no one can make money on our code unless they rip that out first. As Cornell University undergraduate students, we own our original ideas. If this project were to be published, the Tetris aesthetics would have to be replaced.
Ethical Considerations
We have done our best effort to conform to the IEEE Code of Ethics in the design and execution of this project.
Our project is essentially a motion tracking device for the consumer entertainment market. Since it is a class project, it has been created with no intention of profit and in accordance with the beliefs of the GPL. This combination of facts means it was created purely for learning and for fun. Therefore it seeks only to make the world a better place.
The game is based on video output, which means there is a chance it will trigger photosensitive seizures in some users. We have added a warning before the menu screen to alert users to this. We also take that opportunity to warn players about the dangers of motion-based games. Extreme play motions have been known to sometimes cause harm or damage. However, when played safely, our game(s) will improve the health of the user through the physical and mental activity involved.
We have been honest in the reporting of our results, and have strived to write code that does not lie. Our reported resolution is accurate, and our frames per second benchmark is as accurate as our clock will allow.
Because our game is based on video input, a user's appearance and physical fitness will affect their interaction with the software. For this we recommend users consult with their doctor before playing and wear dark colors to aid the camera in tracking them.
Legal Considerations
Our project is a simple video home entertainment device. It does not release excessive EMF and should not cause any interference with other electronics. We have placed warnings in the game about the dangers involved in playing.
Appendices
A. Source Code
Source files
Lab5.c (20KB) – all the ISRs, initialization code, tracking output code, and main state machine
human_tetris.c (6KB) – human tetris game logic and data handling
brick_breaker.c (8KB) – brick breaker game logic including physics and data handling
whack_a_mole.c (5KB) – whack-a-mole game logic and data handling
max7456_learn.c (15KB) – contains code for writing to the OSD’s progmem
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I m Tasneem, a final year student in Electronics & Communications want to share my ZTE (Chinese Telecom Equipment Vendor) experience with you:
There were 22 students, out of which 18 were either 2004,05 or 2003 passouts, I along with 3 others were freshers, Firstly they took a technical test of 100 marks, duration 1 hr:
1. Write all layers of OSI Model and briefly explain them ? - 10 marks 2. What is difference between GSM & CDMA ? - 10 marks 3. Draw any communication model(GSM/CDMA)?- 10 marks 4. Explain all multiplexing techniques(TDMA/FDMA/CDMA)- 10 marks 5. Write about AM,FM & PCM ? - 10 marks
There were 10 questions of 3 marks each & other 10 ,2 marks each ,all fill in blanks along with objective type: Some of questions I m mentioning are :
1. Which Modulation is used in CDMA? 2. How many slots are in E1 ? 3. CDMA 2000 has data rate of ..? 4. Frequency range of CDMA? 5. Which of following are not forward channels? (Pilot,Sync,Access) 6. Class C specification? 7. Bandwith of one time slot? 8. How may bits are in one burst? 9. Which of following connect two networks?(Router,Switch,Hub) 10. CDMA Stands for : 11. Two types of Frequency Hopping
The technical test went excellent for me,after that it was time for 30 minutes aptitude test? Which had some tricky questions like:
1. Which of the two countries have square flags? 2. Which comes after gigabyte? Terabyte & then???
After that, it was time for group discussion. (Topic : Is India Booming ) At the last they took an interview, technical along with hr, well for me they took 25 minutes to complete askin me questions..oopes..big inteview for me..reg my 6 months practical training at Nokia India Pvt Ltd and general questions like why u didn’t opt for MBA,why do u want to join ZTE,weakness 7 good qualities sort of stuff.
What is run time polymorphism
