Parallel data timing sequence – Epson 8900 Series User Manual

Page 202

Communication Interfaces 10-11

The following figure shows the timing sequence for host-to-printer
character-transfer operations. The table on the following page lists
the timing requirements for the operation.

The reference points, a through h in the preceding figure, are keyed to
the table on the following page and to the following character-transfer
sequence.

1. The host writes a character to the parallel data lines (a). (The

data stabilization time, a-b, must elapse before the transfer cycle
can begin and the minimum data hold time, b-c, must elapse
before the host can write a subsequent character.)

2. After writing the character to the interface, the host monitors the

BUSY line to ensure that the printer is ready to receive a character.
If BUSY is inactive, and the required data stabilization time has
elapsed, the host activates STROBE- to begin the transfer cycle.
The leading edge of STROBE- (b) clocks the character into the
printer receive buffer and activates BUSY.

▲

BUSY

DATA1-8

STROBE-

ACK-

reference

line

valid data

parallel data timing sequence

f g