This circuit is a simple 8-bit analogue to digital converter circuit which is connects to PC serial port. The circuit is based on TLC548 A/D-converter chip which is an A/D-converter with serial output.
The output of the TLC548 is not directly suitable for standard serial data reception, so this circuit uses serial port handshaking lines in a nonstandard way which enables the communication between computer and converter chip to be implemented with as few components as possible. The circuit takes all the power it needs from PC serial port.
Technical data of the circuit
Maximum sample rate: 40 000 samples/second (maximum rate of TLC548 chip)
Accuracy of A/D converter chip: 8 databits (+-0.5 LSB)
Computer interface: PC serial port
Interface protocol: Proprietary syncronous serial interface (uses PC serial port as general purpose I/O port)
The following signal diagram tells that signals are needed for controlling the TLC548 A/D conversion chip. The chip needs chip selected (CS) and i/o clock signal (CLK) to operate. The chip gives the conversion results from data output pins (Dout). Those signals are simple and easy to understand and can be easily generated using simple software routine
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