Ecp Mode - Canon BJC-55 Service Manual

BJC-50

2.1.3 ECP mode

In ECP mode, the PeriphAck signal and the HostClk signal handshake to
communicate.
After the host computer negotiates with the printer, the printer raises the PeriphClk
signal and the host computer lowers the HostAck signals. At this point the host
computer sets the data on the bus and lowers the HostClk signal to transmit the data.
When the printer is ready to receive data, it raises the PeriphAck signal. The transfer
from the host computer is complete once the printer receives the data and lowers the
PeriphAck signal.
Next, to send data from the printer to the host computer, the host computer's
ReverseRequest signal is lowered. The printer lowers the AckReverse signal, raises
the PeriphRequest signal and prepares the data to be sent on the bus.
In reverse transfer, the PeriphClk signal and the HostAck signal handshake to
communicate.
The printer sets the data on the data bus and lowers the PeriphClk signal to transmit
data.
The host computer raises the HostAck signal to indicate it is ready to receive the host
computer data.
The transfer of data from the printer is complete when the host computer lowers the
HostAck signal after it receives the host computer data.
Reverse Request
Ack Reverse
Data (1-8)
PeriphClk
Host Ack
Periph Ack
Byte0
Cmd
Tp
Figure 4-8 Interface Timing (ECP Mode)
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Part 4: Technical Reference
Byte1
Cmd
Tp