Canon BJC 50 Service Manual - Page 98

Canon BJC 50 - Color Inkjet Printer Manual

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Part 4: Technical Reference BJC-50 2.1.2 Nibble mode In nibble mode, the printer transfers data twice to the host computer in 4-bit units. The data is transferred with the PtrClk signal and HostBusy signal handshakes. After the printer negotiates with the host computer and enters the nibble mode, the printer confirms that the HostBusy signal is low, outputs a PtrClk signal with a nibble setting on the lower bits and lowers the PtrClk signal. After the host computer receives the lower bit data with the nibble mode, it raises the HostBusy signal. This signals the printer that the host computer has read the nibble data. Next, after the printer confirms that the HostBusy signal is low for a second time, it outputs the upper nibble bits and lowers the PtrClk signals. When the host computer raises the HostBusy signal, the handshake is completed. If there is no data to be sent to the host computer, the DataAvail signal becomes high and the printer stands by for the next data transfer. Host Busy PtrClk Data Avail bit0 bit4 Xflag bit1 bit5 AckDataReq Ptr Busy bit2 bit6 bit3 bit7 Tp Tp Figure 4-7 Interface Timing (Nibble Mode) 4-10

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2.1.2 Nibble mode
In nibble mode, the printer transfers data twice to the host computer in 4-bit units.
The data is transferred with the PtrClk signal and HostBusy signal handshakes.
After the printer negotiates with the host computer and enters the nibble mode, the
printer confirms that the HostBusy signal is low, outputs a PtrClk signal with a nibble
setting on the lower bits and lowers the PtrClk signal.
After the host computer
receives the lower bit data with the nibble mode, it raises the HostBusy signal.
This
signals the printer that the host computer has read the nibble data.
Next, after the
printer confirms that the HostBusy signal is low for a second time, it outputs the
upper nibble bits and lowers the PtrClk signals.
When the host computer raises the HostBusy signal, the handshake is completed.
If
there is no data to be sent to the host computer, the DataAvail signal becomes high
and the printer stands by for the next data transfer.
Part 4: Technical Reference
BJC-50
4-10
bit0
bit1
bit2
bit3
Tp
Tp
bit4
bit5
bit6
bit7
Host Busy
PtrClk
Data Avail
Xflag
AckDataReq
Ptr Busy
Figure 4-7 Interface Timing (Nibble Mode)