Serial Multiplexor

Features:

2 Serial inputs
1 Serial input
Extracts specific data from both ports
Commands select the port to be analysed
3.3V and 5V regulated outputs
CRC data checking
Automatic command sequences

Designed for:

Triskel Marine Ltd

Designed to extract specific data coming in from the two serial ports and pass it on to the master port when requested. The board also has the facility to execute command sequences so the mulitplexing is automatically taken care of, the PC just logs the output from the master port. There are 3.3V and 5V regulators on board along with a "slow" switch on for external hardware, this makes sure the voltages have settled and the multiplexor board is initialised.

The board is based around a PIC16F628A microchip. The two incoming serial ports are bit banged and operate at 4800bps and are buffered through the MAX232 chips. The master PC port uses the onboard PIC USART and also runs at 4800bps through a MAX232 chip. The slow start on is generated by a delay created by the 74HCT123 which drives an N-channel JFET transistor. The whole board runs at 4MHz.