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3.2 Description of communication signals
1.
DB0~DB7
These are parallel 8 bit data receive pins. For more details on the timing of the parallel data reception, refer to
the time chart 3.2-6.
When the SLIN is setting the low level and the RDY outputs low level, the 8 bit data is latched by the STB
signal (low level).
However, until the ACK pulse is output, hold the STB to low level.
2.
RXD
This is the input pin to receive the serial data.
Refer to the timing chart 3.2-7.
When the RDY terminal is in the "LOW" level during the on-line status, the serial data from the host
computer can be received via this terminal.
This incorporates a data buffer for one line.
Every time a line is printed the motor will stop, however when data transmission of the next line is finished
while the printing head is returning it can undergo continuous printing without stopping the motor.
3.
RDY
This terminal is used for parallel and serial data receptions.
The signals received when the RDY signal is on-line notifies the host that the LSI data can be received.
When Using With a Parallel Interface
After verifying that the RDY signal of the host is in the "LOW" level, there is a need to output data DB0-
DB7 and output the STB terminal in "LOW" level.
This LSI will maintain the RDY signal at the "HIGH" level after verifying that the STB terminal is in
"LOW" level.
However, the data read-in is not completed at this time. The data read-in of the LSI is completed only when
an ACK pulse is output.
When Using With a Serial Interface
After verifying that the RDY signal of the host side is in "LOW" level, there is a need to put the RXD signals
in the "LOW" level to perform data communication immediately after.
The RDY terminal is in the "HIGH" level under the following conditions.
a) during power down
b) during off-line
c) during data read-in
d) during printing
What is more, the RDY terminal during system reset will be in the floating status.
14
CBM-909PC Series User'sManual
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