Firmware; Interface; Compatible Mode - Canon QY8-1360-000 Service Manual

Part 4: Technical Reference

2. FIRMWARE

2.1 Interface

The printer is equipped with an IEEE1284-compatible bidirectional parallel interface.
This interface supports compatible mode, nibble mode, and ECP mode.

Compatible Mode

Selectin=High
Autofd=Low
Negotiation
Extensibility
request analysis
0000 0000 *
Nibble Mode
Termination
Figure 4-5 Bidirectional Centronics Specifications Selection Sequence
2.1.1 Compatible mode
In compatible mode, the parallel interface sends data in 8-bit units.
Data is sent using handshaking based on the DATA STROBE, BUSY, and ACKNLG
signals.
When data (Data 1 to 8) and the DATA STROBE signal are input from the host PC, the
printer controller, which controls the parallel interface, outputs a BUSY signal and
latches the data signals as DATA STROBE falls. After the BUSY signal has been
output, the printer controller fetches the latched data via the DRAM bus to the receive
buffer in the DRAM. After writing the data to the receive buffer in the DRAM, the
printer controller outputs an ACKNLG signal, sets the BUSY signal "Low", and waits
to receive the next data from the host PC.
The BJC-7100 can reduce the response time by the operation in the printer driver.
This achieves faster printing, however, this may not work with some host computers.
Compatible Mode:
In compatible mode, signals are sent in one direction only, from
the host PC to the printer, as with the standard Centronics interface.
This is the default mode when the printer is turned on.
Negotiation:
Negotiation is the procedure by which the printer interface adjusts
to bidirectional mode.
1000 0000 *
Extensibility Link
0001 0000 *
ECP Mode
Extensibility Link:
Selectin=Low
This is a part of the negotiation phase, entered when the value
of the received extensibility request is (1000 0000). The bidirectional
mode and device ID, etc., are exchanged in this phase.
Termination:
The interface returns from nibble mode or ECP mode to compatible
mode in this phase.
0.5 s
Min.
Data 1-8
STROBE
BUSY
ACKNLG
Figure 4-6 Interface Timing (Compatible Mode)
* Value of extensibility
request
Rejection
0.5 s 0.5 s
Min. Min.
Min.0.8 s
4ms (When HS mode is invalid)
4-6
BJC-7100