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Technion – Israel Institute of Technology Department of Electrical Engineering

Project performed by:. Safi Seid-Ahmad Emile Ziedan. Project supervised by:. Michael Itzkovitz. Technion – Israel Institute of Technology Department of Electrical Engineering High Speed Digital Systems Lab. Color Detection For Blind. D 0 2 1 3. Midterm Presentation.

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Technion – Israel Institute of Technology Department of Electrical Engineering

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  1. Project performed by: Safi Seid-Ahmad Emile Ziedan Project supervised by: Michael Itzkovitz Technion – Israel Institute of Technology Department of Electrical Engineering High Speed Digital Systems Lab Color Detection For Blind D 0 2 1 3 Midterm Presentation 30/12/03 , Winter 03/04

  2. Project Goal Building a prototype of a device that is capable of detecting object colors for the use of blind people. The system informs the user of the color by a voice message. • This device should be: • Simple to use. • Portable. • Inexpensive.

  3. How do we define colors? There are various representation models for colors. We are dealing with RGB model. The idea behind this model is simply that every visible color can be represented as a combination of 3 basic colors: Red, Green and Blue. For example:

  4. Light Source Driver Light Source Block Diagram Microcontroller Red -Freq Red RGB Calculation Color Determination Light Analyzer Driver Green -Freq Green  Light Blue -Freq Blue Analyzer Object Voice Memory Driver Voice Memory Orange Speaker driver Speaker Analog signal

  5. System Functionality When the user presses the operation button, The light source emits light on the object to be reflected towards the light sensor. The sensor is controlled by the PIC in order to perform 3 measurements; for Red, Green and Blue components of the object color.

  6. System Functionality How can the PIC detect the color? The PIC calculate RGB values by comparing the output of the color sensor to min and max frequencies which have been already measured (see Calibration process). The RGB values are compared to colors inside a look table, according to that the PIC finds the color with the closest RGB values to the calculated RGB of the object.

  7. System Functionality How would the user be informed? The user is informed of the color by a voice message. Messages declaring the colors in the table are stored in a voice memory controlled by the PIC microcontroller.

  8. Calibration process When using the TCS230, it is necessary to do a ‘white calibration’ before taking any readings to counteract any offsets or environmental effects. For instance, if your light source is white but has a blue component to it, then it will give a higher reading on the blue channel. This can be calibrated out in the TCS230 by having the sensor stare at a white target and bringing the values of each of the channels to maximum.

  9. Programming Environment One option is the TCS EVM: Which is an evaluation module for the TCS230. It consists of a board with TCS230, and a microcontroller. Advantages: There are two white LEDs placed beside the sensor for lightning the aria which is right under it. Disadvantages: 1) It is expensive : about 150$. 2) BasicStamp programming envirument is not present in the lab.

  10. Programming Environment Second option is the PIC DEM 2 PLUS : This is a programming environment for PIC. It is available in the lab and is being used in other projects. The PICDEM 2 Plus can be used stand-alone with a programmed part, with an in-circuit emulator The programming of the PIC is done in a c-like language, this is better than programming in BasicStamp because it is a higher lever language. Finally we will use this board.

  11. Choosing Chips In choosing the chips we considered the following: • They all can operate at approximately low power supply, • this is important for portability requirement. • The micro controller I/O pin number, for controlling the light analyzer and the voice memory chips and to communicate with • the voice memory… • The protocol for communication between the micro controller and the voice memory. • All the chips should be inexpensive.

  12. Choosing Chips Light Analyzer: We chose the new TAOS TCS230 programmable color light to frequency converter since it is suitable to our goal. For each measurement the sensor’s only output is a square wave with frequency directly proportional to light intensity. The light-to-frequency converter reads an 8 x 8 array of photodiodes. Sixteen photodiodes have blue filters, 16 photodiodes have green filters, 16 photodiodes have red filters, and 16 photodiodes are clear with no filters. The result is that we can measure the intensity of the red, green and blue components of color.

  13. Choosing Chips Voice memory: It is used to describe the color in a voice message to the user. We will use the Winbond ISD4002 chip which has enough memory and record/playback features. The ISD4002 supports SPI protocol for communication with a micro controller. Storing messages in the ISD is done in a circuit used for recording. This circuit includes also a micro controller and a microphone.

  14. Choosing Chips Micro controller: We chose the PIC18F252 which has all the features we need, an interface to communicate with the other chips, enough memory, low power, etc… (see specifications section). In addition, this micro controller is compatible with SPI Protocol.

  15. Components Diagram Light Source TCS230 PIC18F252 ISD4002 Speaker Microphone

  16. Specifications • TAOS TCS230: • A programmable color light-to-frequency converter • Vdd = 5 V • Idd = 2 mA (Power-on mode) • 7 uA (Power-down mode)

  17. Specifications • MICROCHIP PIC18F252 • High Performance, Enhanced FLASH Microcontroller • Vdd = 5 V • Idd = 0.5 – 1.5 mA • Supports SPI protocol • Memory:

  18. Specifications • WINBOND ISD4002: • Single-chip voice record/playback solution • Vcc = 3 V • Icc = 15 mA (Playback) • 25 mA (Record) • Isb = 1 uA (Standby) • 120 seconds duration • SPI interface

  19. Project Proccess • What have been already done: • Searching the internet for info on color detection • Choosing and ordering chips. • Studying the datasheets. • Whole system design. • Building a test circuit for TCS230. • Solving the sensitivity problem by moving the TCS into an optical mouse package.

  20. Problems Technical problems: We haven’t received ISD4002 chip yet. We were supposed to get our own PIC demonstration board, but there is no available one. Only next week we will start to share a board with another group.

  21. Problems There were two major problems in dealing with the TCS230 (the color sensor): • The TCS230 is very sensitive to the environment light condition, so it should receive the light that is only reflected from the object. • Since it is very sensitive, we need a light source that is as stable as possible, and contains almost all the visible spectrum of the light.

  22. Solutions The solutions that we have chosen are (we had already implemented): • We are using the package of a PC optical mouse, since it is suitable to our purpose – we put the TCS230 instead of the mouse light sensor… • We used a WHITE LED – it is the ultimate choice we have seen…

  23. Time Schedule

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