Control circuit

This page explains about control circuit of the robot. The control circuit consists from several units for convenient testing and easy to divert them to the other robot. The unit of the circuit is "parallel port adapter", "signal generator", "signal distributor", "sensor board" and "RC decoder".
[Parallel port adapter] [Signal generator] [Signal distribution board]

[Sensor board] [RC decode board]

Parallel port adapter

This is connected to parallel port of Win95 PC. The adapter consists of TTL IC 74LS139, 74LS273 and 74LS244. There are three 8 bit output ports and one 8 bit input port.

Signal generator (servo controller)

This controller generates signal for 24 servomotors. The signal is generated by Z80 compatible microcontroller (Z84C1106) card. One NE555 to generate 47Hz base timing pulse and one 74HC107 for handshake is added outside of the card.

	The 50-pin cable (right side of the board) comes from RS232 interface board. The 20-pin cable is connected to the robot. The 40-pin cable is connected to PC or Pocket computer. The cable that connects this board and the robot is about 3 m.
	The board on the top of this controller is expanded. The 10-pin cable is connected to the connector at the left side of the RS232 interface board for serial communication.
	The Z80 CPU card is removed.
	This is a close-up of the CPU card. The clock frequency of this card is 6MHz and equipped with 32Kbyte of ROM and RAM. The Z84C1106 has five sets of 8 bit I/O and four sets of counter/timer.
	The waveform shown left is the signal that is output to the robot through the 20-pin cable. There are three lines for servo control signal. The signal for 8 servomotors is gathered in each of the line. When TTL IC is connected with long cable (over 30 cm), problem about reflection of signal and noise may be considered. But the frequency of these signals is low enough. So ICs are just connected in this controller.

Signal distribution board

This board distributes the signals for servomotor from signal generator.

The circuit diagram can be downloaded for a reference. The diagram is not complete (because it is drawn for my memorandum) but I think this will help to understand what it is. (31 Kbyte GIF file)

Sensor board

This is a board to connect touch sensor in the feet, IR sensor for line trace and inclination detection sensors. This board is consists of three 74HC244 and a 74HC138.

RC decode board

This board converts the signals from RC receiver into 4 bit binary code. The conversion is done by PIC16C84-04. The PIC16C84-04 and the RC receiver is photo isolated.