µPD16661A
7. CPU INTERFACE
7.1 Function of the RDY (Ready) pin
The on-chip RAM uses a single-port RAM. In order to avoid conflict between accessing from the CPU side
and reading on the liquid-crystal drive side, the RDY pin performs a wait operation on the CPU.
5 (1) Timing
A0 to A16,/UBE
/CS
/OE,/WE
Hi-z
RDY
Hi-z
Wait
Ready
Wait
(2) Connection of the RDY pin
The RDY pin uses a 3-state buffer. Externally attach a pull-up resistor to the RDY pin.
When more than one µPD16661A is used, wired-OR connect each LSI RDY pin.
CPU
Ready input
VCC2
Pull-up resistor
RDY
Column driver
RDY
Column driver
14