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Writing a Parallel Communication Driver
D–3
Publication 17706.5.20 - June 1997
Pin
NIBBLE Mode
BYTE Mode
Pin Notation
17
Select Input
Host Transmit Control
(Host/KFC15/KFCD15)
Host Transmit Control
(Host/KFC15/KFCD15)
1825
Ground
Ground
Ground
The host communication software must turn on pin 17 (Host
Transmit Control) to transmit data and reset it to receive data from
the KFC15/KFCD15 module. Every byte transmitted to the
KFC15/KFCD15 module must be clocked with a positive transition
on pin 1. Every byte or nibble sent from the KFC15/KFCD15
module must be clocked with a positive transition on pin 10.
The status indicators signify the following:
BUSY—a device is busy processing
EOT—a device has completed transmission
ACK—a transmission has been received
To reset parallel communications at any time, the host should reset
pin 14 (Auto Feed) and set its data clock (pin 1). Then, the host
device follows by resetting both pin 17 (Select Input) and pin 16
(Initialize Printer). The KFC15/KFCD15 module should
acknowledge by resetting its Busy and its Acknowledge lines.
The host should set Busy whenever it is reading a byte or nibble sent
to it from a KFC15/KFCD15 module, resetting it when ready for the
next piece of the DF1 message.