/Color-Based-Sorting

Primary LanguageC

color_based_sorting

color_based_sorting Color based sorting system ─ Group Mentors: MANASVI MEET SONI RIYA Group members: Dhruv Oza Vinit Vinit Mairal Anshoo Rajput Prashant Dodiya Prabhakar Jaiswal

Introduction to our project In this project we are going to learn and build a prototype of a machine which sort mixed color objects according to their color. For this we are going to use a color sensor TCS 3200 which senses the color and converts intensity into frequency which a microcontroller can understand. The basic function of its working will be like we have to give mixed object of RED, GREEN and BLUE color and it will put them in three different buckets. Basic things we learned:

  1. The basics of a timer/counter function of microcontroller ATmega 32
  2. embedded C programming
  3. The working of TCS 3200 color sensor
  4. PWM generation and implementation via atmega32
  5. UART communication using serial usb ttl Major Components Required:
  6. Atmega32
  7. 2 Servo Motors
  8. A Color sensor - TCS3200
  9. 12V Power source and voltage regulator circuit
  10. Plywood for mechanism
  11. PL2303(USB -TTL)

Software used: Atmel studio Xtreme burner AVR XCTU

Introduction of Timer and Counter function of ATmega32

For working with TCS3200 color sensor and servos we must learn to work with timer clock function of a microcontroller as we are working with frequencies and PWM (pulse width modulation) which is necessary for actuation of servo motor Goals

I. How to learn Datasheet For getting familiar with a microcontroller and different sensors and to learn its whole working and application datasheet is a must as it comprises of the pinout diagram and specification.

II. To learn timer counter registers ATmega 32 microcontrollers come with an inbuilt clock of frequency 16MHz and 4 clock pins 2 8-bit timer/counter and 2pins of 16bit 8-bit Timer/counter register is TCCR0 and for 16 bit it is TCCR1A/B and few more III. Different methods of data manipulation, left shift and Right shift For making different bits high or low without affecting other pins we use left shift or right shift like we want to high pin A1 of port A high letting other pins as it is we can write PORTA |= (1<< PINA1);

Generating PWM with timer/counter PWM It stands for pulse width modulation. Nowadays, it is widely used to control electronic circuits. For example:- 1) it can be used to control the brightness of LED 2) Controlling speed of motor 3) Efficient power supply etc.. For modulating LED we apply pulsing power supply (on and off) at a certain frequency and with certain pulse width. By adjusting the pulse width we decide the duty cycle of load, which is the time period of signal for which it is high. TIMER WITH PWM Timer/counter1 is needed to use pwm. It basically counts oscillation going on. According to resolution of timer ( 8bit or 16bit) we have to encode the value of duty cycle. 8bit counter/timer counts from 0 to 255 16bit counter/timer counts from 0 to 65535 Prescaling of this timer is also done to increase the time duration of one count of the timer. As 8bit timer counts up to 255 only we can prescale it upto 255 only (considering 255 as 1 count).Due to which the output compare match that we wanted for servo motor(explained in detail later) to work did not come into range. So we went for 16bit timer/counter1 with prescaling of 64. We configured timer1 using microcontroller datasheet(atmega32). MODES OF OPERATIONS There are 4 modes in timer1:-

  1. Normal mode
  2. CTC mode
  3. Fast PWM mode
  4. Phase correct PWM mode We have configured timer1 in fast pwm mode which provides a high frequency PWM waveform generation option. The fast PWM differs from the other PWM options by its single-slope operation. The counter counts from BOTTOM to TOP then restarts from BOTTOM. In noninverting Compare Output mode, the Output Compare (OC1x) is cleared on the compare match between TCNT1 and OCR1x, and set at BOTTOM. In inverting Compare Output mode output is set on compare match and cleared at BOTTOM.

Activating servo motor A servo motor is an electrical device which can push or rotate an object with great precision. If you want to rotate an object at some specific angles or distance, then you use servo motor. It is just made up of simple motor which runs through servo mechanism.

TCS3200 RGB color sensor

The sensor has four different types of filter covered diodes. In the 8 x 8 array of photodiodes, 16 photodiodes have Red filters, 16 have Blue filters, 16 have Green filters and the rest 16 photodiodes are clear with no filters. Each type can be activated using the S2, S3 selection inputs. Since each photodiode are coated with different filters each of them can detect the corresponding colours. For example, when choosing the red filter, only red incident light can get through, blue and green will be prevented. By measuring the frequency, we get the red-light intensity. Similarly, when choose other filters we can get blue or green light. We can also set the frequency scaling option by using the S0, S1 select lines. Pin Configuration PIN NAME PIN NUMBER DESCRIPTION GND 4 Power supply ground. All voltages are reference to the ground. VCC 5 Supply voltage OE 3 Enable for FO (Active low) OUT 6 Output frequency (fo) S0, S1 1, 2 Select lines for output frequency scaling S2, S3 7,8 Select lines for photodiode type. 7 S0 S1 OUTPUT FREQUENCY SCALING(f0) L L Power down L H 2% H L 20% H H 100% S2 S3 PHOTODIODE TYPE L L RED L H BLUE H L CLEAR (NO FILTER) H H GREEN This TCS3200 color sensor module consist of a TAOS TCS3200 RGB sensor chip and 4 white LEDs. The main part of the module is the TCS3200 chip which is a Color Light-to-Frequency Converter. The white LEDs are used for providing proper lighting for the sensor to detect the object colour correctly. This chip can sense a wide variety of colours and it gives the output in the form of corresponding frequency. This module can be used for making colour sorting robots, test strip reading, colour matching tests etc. To determine the colour of an object, we’ve to measure the frequency from 6th pin OUT when each filter is activated. Set both S2 and S3 to LOW, measure the frequency. Now we get the intensity of RED component in the object. Set S2 to LOW and S3 to HIGH in order to get the intensity of BLUE component in the object. Set both S2 and S3 to HIGH and get the intensity of GREEN component in the object. 8 Compare the frequencies of the three components to get the actual colour of the object. 9 USART and UART- • what is USART? • Difference between USART and UART • what was the need to use UART? • problem faced during the initial stage of using UART

  1. A USART (Universal Synchronous/Asynchronous Receiver/Transmitter) is a microchip that facilitates communication through a computer's serial port using the RS-232C protocol. ... However, unlike a UART, a USART offers the option of synchronous mode.
  2. Difference between USART and UART a. The first difference between a USART and a UART is the way in which the serial data may be clocked. A UART generates its data clock internally to the microcontroller and synchronizes that clock with the data stream by using the start bit transition. ... A USART, on the other hand, can be set up to run in synchronous mode b. In synchronous mode, the data is transmitted at a fixed rate. In asynchronous mode, the data does not have to be transmitted at a fixed rate. c. Synchronous data is normally transmitted in the form of blocks, while asynchronous data is normally transmitted one byte at a time. d. Synchronous mode allows for a higher DTR (data transfer rate) than asynchronous mode does, if all other factors are held constant.
  3. The main reason behind using UART communication is to know the exact frequency required to operate TCS3200.
  4. Along with great communication data buses UART also play a major role in debugging phase. Using UART enables us to use GUI softwares like X-CTU or realterm which helps in receiving the characters or number that we needed to pass. It makes easy for us to interpret the bug in the code. 10 Problems faced – A. Determining of baud rate to be worked on was a tough job. To know that we tried both 9600 and 1200 baud rate. B. Getting a character value on the X-CTU cannot be done directly by using the "char" keyword so we had to initialize the variable using uint8_t which means undefined variable with memory space allotted 8 bits. C. The major problem is to print get an integer value on the x-ctu. To get that tried to
  5. Initialize the variable directly as int.
  6. Initialize the variable as uint8_t.
  7. Initialize the variable as char and the passing the integer value indirectly.
  8. The first problem faced by us was writing the receiving and transmission function. So, by
  9. using the datasheet of atmega32 and some web links, we gathered ideas and information and
  10. with a lot of effort, we finally coded it. After that while we were writing the rest of the code and
  11. compiling it, the error was popping up about the unknown names of registers and bits used such
  12. as UCSRB, UCSRC, UDRE, etc. which are commonly used registers. We asked our mentors
  13. about this and they advised us to make the executable file for the UART code as the compiler
  14. don't know what they are.
  15. After that, we tested our code by sending a character by setting baud_rate: 2400 and
  16. frequency of microcontroller F_CPU: 16 Mhz and accordingly setting the value of UBRR as per
  17. the formula:
  18. UBRR= (F_CPU/16*baud_rate) -1;
  19. but the test result was just an infinite series of dot which was obviously not expected. We tried 11
  20. with various baud_rate and accordingly setting the value of UBRR but all in vain.Then after our
  21. mentor advised us by their past experience to set the baud_rate: 1200 bps and UBRR= 51 and
  22. we were getting the perfect result.
  23. It was contradictory to the formula mentioned in the datasheet. For the baud_rate: 1200 bps the
  24. calculated value of UBRR must be 832, but we can't neglect the fact and still we couldn't find
  25. out why it was happening.
  26. After transmitting a character, we then moved forward to transmit the integer. We
  27. declared uint8_t num variable and assigned 32 to it and on testing it we were getting the its
  28. correct hex value but the integer 32 was not getting printed. We are still working on this error.