TeamUR finally got the circuit!
As microcontroller PIC16F73 (Microchips)
have been chosen, mainly because of cost efficiency,
ability to upload a program without removing MCU from a circuit, and availability
of Serial Peripheral Interface. This chip contains wide variety of
components like timers (3 of them, PWM), A/D inputs, support for I2C and SPI
serial bus, 3 8bit ports, ability to use simple bootloader and most of
everything Flash memory. The microcontroller requires minimal number of
external components to work.
To drive mini DC motors Quadruple Half-H Driver SN754410 (Texas Instruments)
has been used. One chip is able to take care of both DC motors.
Probably, in the future, PIC's PWM capability will be utilized to change motor
rotation speed.
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Both ICs are placed on the universal PCB. In addition
+5V integrated stabilizer 78L05 is used because the battery gives
approximately 7.2V. The motors are powered from full voltage
thorough SN754410. We are thinking about using very energy efficient
LM2595 (National Semiconductor) On the board you can see 4MHz quartz oscillator,
which let PIC to run in 1us instruction cycle. |
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The other side of the board doesn't look as neat as the
top. |
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The robot at this stage is equipped with
IR Proximity Detector assembled and tested earlier. |
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The back side shows main switch, which could be
smaller... The battery wires in the future will be ended with a nice
socket. |
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Front view: am I looking serious? |
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Oups! The wheels could be better aligned. the
truth is that the robot doesn't move straight. But we are not very concerned
with this fact because control over the robot movement direction must be
taken care by kind of PID controll. |
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Bird-eye view. |
