Canon BJC-55 Series, Service Manual

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2. FIRMWARE
2.1 Interface
The printer supports a parallel interface and IrDA interface. The parallel interface is
compatible with the bidirectional Centronics interface-standard (IEEE 1284).
Compatible mode is the same as the Centronics interface-standard protocol. IrDA is an
infrared data communication interface that is compatible with IrDA (1.0). The interface
data transfer timing for each of the parallel interface mode is described below.
2.1.1 Compatible mode
The parallel interface for the compatible mode transfers data in 8-bit units. Data is
transferred with the STROBE, BUSY, and ACKNLG handshake signals.
When the printer receives the data (Data 1-8) and a STROBE signal from the host
computer and if the STROBE signal is low, then the printer controller which controls
the parallel interface outputs the a BUSY signal and latches the data. After the BUSY
signal is output, the printer controller sends the latched data from the DRAM bus to
the receive buffer in the DRAM. After the data is completely written into the receive
buffer in the DRAM, the printer controller outputs the ACKNLG signal and sets the
BUSY signal to "Low". It then waits for the next data input from the host computer.
4-9
BJC-50
Part 4: Technical Reference
BUSY
ACKNLG
3.5
µ
s min.
1.0
µ
s
min.
DATA 1-8
STROBE
1.0
µ
s
min.
1.0
µ
s
min.
Figure 4-6 Interface Timing (Compatible Mode)