HD66712 Datasheet, PDF (39/88 Pages) Hitachi Semiconductor – Dot-Matrix Liquid Crystal Display Controller/Driver

HD66712U
• Transmitting (read)
: After receiving the start synchronization bits, the R/ bit (= 1), and the RS bit with the start byte, 8-
: ^{bit read data is transmitted in the same way as receiving. When read data is continuously transmitted}
with R/ bit and RS bit unchanged, continuous transfer is possible (see “Continuous Transfer”
below).
Even at the time of the transmission (the data output), since the HD66712 monitors the start
synchronization bit string (“11111”) by the SID input, the HD66712 receives the R/W bit and RS bit
after detecting the start synchronization. Therefore, in the case of a continuous transfer, fix the SID
input “0.”
• Continuous transfer
: When instructions are continuously received with the R/ bit and RS bit unchanged, continuous
receive is possible without inserting a start byte between instructions.
After receiving the last bit (the 8th bit in the 2nd byte) of an instruction, the system begins to execute
it.
To execute the next instruction, the instruction execution time of the HD66712 must be considered. If
the last bit (the 8th bit in the 2nd byte) of the next instruction is received during execution of the
previous instruction, the instruction will be ignored.
In addition, if the next unit of data is read before read execution of previous data is completed for
busy flag/address counter/RAM data, normal data is not sent. To transfer data normally, the busy flag
must be checked. However, it is possible to transfer without reading the busy flag if wiring for
transmission (SOD pin) needs to be reduced or if the burden of polling on the MPU needs to be
removed. In this case, insert a transfer wait so that the current instruction first completes execution
during instruction transfer.
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