UPD17073 NEC, UPD17073 Datasheet - Page 171

• Manufacturer Part Number: UPD17073
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER WITH HARDWARE FOR DIGITAL TUNING SYSTEM
• Manufacturer: NEC

19.2.4
input to any one of the P1A0, P1A1, P1A2/AD0, and P1A3/AD1 pin.
(1) When using general-purpose output port as key source signal
(2) To release halt by other microcontroller
To release the halt mode by key input, the HALT instruction is specified as “HALT 0001B”.
With the key input specified as the halt release condition, the halt mode is released when a high-level signal is
However, halt mode cannot be released by a pin disconnected to the pull-down resistor.
To use a general-purpose output port as the key source signal, make the output port high-level, and execute
the “HALT 0001B” instruction.
When an alternate switch is used at this time as switch A in the above figure, a high-level is always input to
the P1A0 pin while switch A is closed, and the halt mode is immediately released. Therefore, care must be
exercised when key input is specified as the halt mode releasing condition and an alternate switch is used.
The P1A0, P1A1, P1A2/AD0, and P1A3/AD1 pins can also be used as general-purpose input ports with pull-
down resistor.
Therefore, other microcontrollers can also be used as shown above after the halt mode has been released.
Releasing halt by key input
Microcontroller,
Output port
etc.
Switch A
P1A3/AD1
P1A2/AD0
P1A1
P1A0
General-purpose output port
General-purpose output port
P1A3/AD1
P1A2/AD0
P1A1
P1A0
Latch
PD17072,17073
Latch
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