Transmission Protocol Description; Timing Diagram - Epson PP 408 User Manual

- Maximal Transfer Speed
The maximum throughput for data transfer is 5,000 characters per second.
3.1

Transmission Protocol Description

After Power-ON the PE (Paper End) signal is set to logic 0 and the SELECT and
¯¯¯¯¯¯¯ signals are set to logic 1.
FAULT
The printer is now ON-LINE and ready to receive data.
Timing
The host sets a print/control character to the 8 data lines.
After a time delay of a minimum of 0.5 µs, the host sends a ¯¯¯¯¯¯¯¯¯
of a minimum of 0.5 µs. The print/control character is accepted into the interface
buffer and the printer transmits a BUSY signal to the host. When the data byte
is accepted into the interface buffer the printer transmits a BUSY signal and an
¯¯¯¯¯¯ pulse.
ACKN
The ¯¯¯¯¯¯ pulse informs the host that the data has been received and that
ACKN
the printer is ready to receive new data.
If the interface buffer is full except for the last character the BUSY is not reset in
order to stop the data transfer from the host. The BUSY signal is only reset if
space is available in the interface buffer for a minimum of 256 characters.
When pressing [START/STOP] the BUSY remains high and no ¯¯¯¯¯¯
Provided a minimum of 256 characters are available in the interface buffer,
pressing [START/STOP] will reset BUSY and transmit the ¯¯¯¯¯¯
Appendix A System Interface Description
pulse
STROBE
is sent.
ACKN
pulse.
ACKN
A-9
Appendix A System Interface Description
3.2

Timing Diagram

DATA 1 - 8 DATA
))))))))))))
STROBE
350 ns max
BUSY
))))))))
ACKN
A-10
0.5 Fs
0.5 Fs
0.5 Fs