Fujitsu Impact 3650, Руководство по обслуживанию

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(2) Circuit for generating a strobe signal (Ptr Clk) for data transmission from the printer
MB90706
*Ptr CLK
*ACK 10Pin
*ACK * Ptr Clk
[Centronics control circuit]
Figure 5.3.9 shows a general timing chart for the Centronics control circuit.
The Centronics control circuit latches received data DATA1 to DATA8 to the internal register at the falling edge of
data
strobe signal *DSTB, and simultaneously sends an interrupt signal to the external interrupt control circuit to
inform the
MPU of the receipt of data.
The MPU checks that external data has been input, reads the data, and then stores it in DRAM.
After the interrupt is released from the MPU, BUSY is reset and *ACK is sent.
DATA1-8
*DSTB
BUSY
*ACK Data reading
Interrupt to MPU
Figure 5.3.9 Interface timing chart
[Anti-noise external interrupt circuit]
The anti-noise external interrupt circuit reads the results of sampling INPRM and EXPRM twice at about
12-microsecond intervals. It thus prevents malfunction by noise, and receives forcible reset signals INPRM
and EXPRM and then causes an interrupt to the MPU.
The MPU initializes the printer based on the interrupt signal.
LS08