Ecp Mode - Canon BJC 6000 - Color Inkjet Printer Service Manual

Part 4: Technical Reference

2.1.3 ECP mode

The ECP mode allows data to be transferred bi-directionally between the printer and
host computer. This mode also allows 2 byte data transfer to provide faster data
transmission and reception. It is for this reason that ECP mode is suitable for
transferring large amounts of data.
In response to the fall of the ReverseRequest signal, the direction of the data bus
switches from forward data transfer mode to reverse data transfer mode. The forward
data transfer mode allows data to be transferred from the host computer to the
printer, whereas the reverse data transfer mode allows data to be transferred from the
printer to the host computer.
(1) The host computer causes AckReverse to go low to request reverse data transfer
(data transfer from printer to host computer).
(2) After confirming AckReverse is low, the printer causes AckReverse to go low to
indicate that that reverse transfer is possible.
(3) The printer sends 1 byte of data out on the data lines and causes PeriphAck to go
high to tell that this data is not command but data. The printer then causes
PeriphClk to go low to tell that this data is valid.
(4) After confirming the signal in (3) is received, the host computer causes HostAck to
go high.
(5) The printer causes AckReverse to go high to have the data recorded in the host
computer.
(6) The host computer causes HostAck to go high to get ready for the next one byte of
data.
(7) The printer repeats the process above to send the next one byte of data.
PeriphClk
Host Ack
Data (1~8)
PeriphAck
ReverseRequest
AckReverse
Figure 4-11 Interface Timing (ECP mode, reverse transfer)
Byte0 Byte1
Data Cmd
Reverse transfer phase
4-12
BJC-6000