PD17012_15 Datasheet, PDF (258/320 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

µPD17012, 17P012
21.4.3 Releasing halt status by key input
Releasing the halt status by key input is specified by the HALT 0001B instruction.
If releasing the halt status by key input is specified, the halt status is released when a high level is input to
any of the four pins P0D0/K0 to P0D3/K3.
The following paragraphs (1) through (3) explain the points to be noted when using a general-purpose output
port for a key source signal and when multiplexing LCD segment signal outputs with key source signal outputs.
(1) Notes on using general-purpose output port for key source signal
Switch A
P0D3/K3
Latch
P0D2/K2
P0D1/K1
P0D0/K0
General-purpose output port
The HALT 0001B instruction is executed after a general-purpose output port for key source signal goes
high.
If an alternate switch such as switch A in the above figure is used at this time, a high level is always applied
to the P0D0/K0 pin while switch A is closed, and the halt status is immediately released.
Therefore, care must be exercised in using the alternate switch.
When using a general-purpose output port for key source signal, reset the KSEN flag of the LCD mode
select register (RF address 10H) to 0.
At this time, the P0D0/K0 to P0D3/K3 pins are automatically pulled down.
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Data Sheet U10101EJ4V0DS