
CHAPTER 5 BUS CONTROL FUNCTION
User’s Manual U15905EJ2V1UD
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5.6.2
External wait function
To synchronize an extremely slow external device, I/O, or asynchronous system, any number of wait states can be
inserted in the bus cycle by using the external wait pin (WAIT).
Access to each area of the internal ROM, internal RAM, and internal peripheral I/O is not subject to control by the
external wait function, in the same manner as the programmable wait function.
The WAIT signal can be input asynchronously to CLKOUT, and is sampled at the falling edge of the clock in the T2
and TW states of the bus cycle in the multiplexed bus mode. In the separate bus mode, it is sampled at the rising
edge of the clock immediately after the T1 and TW states of the bus cycle. If the setup/hold time of the sampling
timing is not satisfied, a wait state is inserted in the next state, or not inserted at all.