Star Micronics TSP400 technical manual THEORY OF OPERATION 2. Main and Interface PCBs

THEORY OF OPERATION

2.Main and Interface PCBs

The main PCB and interface PCB provide the drive circuitry for the TSP-400 printer series. The two boards are connected via 40-pin connectors.

2-1. Interface
2-1-1.	RS232C interface
	CN3		CN1	IC10
				CN9
	IC1			Gate array	IC5
	D2O	D2I	B12	B12	CPU
	DTR			ACK
	R-CH
	D1O	D1I	B14	B14	TXD0
	TXD
	R1I	R1O	A15	A15	RXD0
	RXD
	R2I	R2O	B15	B15	RXD1
	CTS
	HD151232FP

RS232C Interface PCB Main PCB

Fig. 2-2 RS232C Interface

Data flow from host to printer: IC1 receives serial data from the host computer via RXD, converts the signal voltage from RS232C level to TTL level, and passes the result to the CPU. The CPU converts the serial data to parallel and stores it into buffer memory.

Data flow from printer to host: The CPU generates data, converts it into serial form, then passes it to IC1. IC1 converts the signal voltage from TTL level to RS232C level, then outputs the result over the TXD line.

The CTS line is hardware-connected, but the connection is not recognized by software. (The printer does not monitor the signal.)

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