Canon Color Bubble Jet BJC-2000 Series, Service Manual

Page: 44 / 136

ECP mode
In ECP mode, the printer transfers data at once in 8-bit units allowing faster data
transmission and reception. This mode is suitable for large data transfers such as
for scanners.
After the computer responds to the Low Reverse Request signal, the AckReverse
signal goes Low and the data bus direction switches from the forward data
transmission phase (host computer to printer) to the reverse data transmission
phase (printer to host computer).
During the reverse data transmission phase, the HostAck signal confirms that the
PeriphClk is High before it goes Low. HostAck signal goes Low when the printer is
ready to receive data from the host computer. The host computer raises the HostAck
signal after it receives the data.
During reverse data transmission, a high PeriphAck signal represents "data" whereas
a Low signal represents a "command."
Part 2: Product Specifications BJC-2000
2-20
BJC-2000
0001 0000
1284 Active
Data (1 ~ 8)
Host Ack
Host Clk
Periph Clk
Xflag
TP
TP TP
Periph Ack
Periph Req
Byte0
Byte1
nCmd nCmd
ECP mode Support
TP
TP: minimum set up
Ack Reverse
Figure 2-12 Timing Chart (ECP Mode)