devilcat
electronics
control board:

• bi-directional parallel port interface
• ADC0809 8-bit analog-digital converters (x2)
• LS7266 dual quadrature decoder/counter
• ATF1502 cpld (motor control)
• 74HCT573 digital input latch
• 74HCT573 digital output latch

motor control functions of the motor control board are obsoleted by the (new) motor control board.
The main control board, mounted on the middle deck behind the motors, connects the computer to devilcat's electronics. The control electronics are accessed by the computer through an 8-bit data bus connected to the parallel port. One parport control line is used to latch an address into a 74HCT573, the 3 MSb's of which are then decoded by a 74HCT138 to select a peripheral. The computer can then initiate a read or write using two more control lines. Using direct programmed IO on the parport this results in a maximum of ~100K 8-bit operations per second.

The board above and to the left of the control board houses an LM2576 switching dc-dc converter to power the 5v control electronics from the 24v batteries.

drive board:

• 2 IRF3710 h-bridges w/ IR2104 drivers
• 555 high-side sustain (~36v) charge pump
• 5v & 12v LM2574 switching power regulators

The drive board, mounted under the motors, contains two mosfet h-bridge motor drive circuits and various support electronics.

sonar board:

• 20MHz PIC16F877 mcu
• 40 KHz sonar tranciever, multiplexed 8 ways.

The sonar board can drive 8 pairs of piezo sonar transducers. Interference rejection and variable gain allow reception at ranges up to several meters.

sensors:

8 GP2D12 infra-red rangefinders and 2 pairs of sonar transducers are mounted under the outer edge of the middle deck.

motor control board: no picture available
The motor control board contains an ATmega323 AVR processor, a quadrature decoder, and a usb interface. The computer uploads velocity profiles through the usb port and the avr drives the motors according to those profiles using a closed loop PID system running at 450 hz.