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CHAPTER 15 BUZZER OUTPUT
15.3 Pin of the Buzzer Output
The pin related to the buzzer output is P37/BZ/PPG.
■ P37/BZ/PPG Pin
The P37/BZ/PPG pin works as a general-purpose I/O (P37) pin, output pin for the buzzer output (BZ), or
output pin for the 12-bit PPG (PPG).
● BZ pin
The BZ pin outputs the square wave for the buzzer of the frequency having been specified for the BZ pin.
When a buzzer output frequency is specified (other than BZCR:BZ2,BZ1,BZ0=000
B
), the P37/BZ/PPG pin
automatically works as the BZ pin regardless of the value of output latch. Even if the PPG output has been
enabled, it works as the BZ pin that has higher priority.
■
Block Diagram of the Pin Related to the Buzzer Output
Figure 15.3-1 Block Diagram of Pin Related to Buzzer Output
Note:
If pull-up resistor supported is specified by the pull-up setting register, the state of the pin in stop mode
(SPL=1) is not Hi-Z but "H" level (pull-up state). During a reset, however, the pull-up is disabled and
the state is Hi-Z.
DDR
Pch
Nch
PDR
PUL
P37/BZ/PPG
(SPL=1)
Internal data bus
PDR read
Stop mode (SPL=1) Pull-up resistor
Peripheral output
Peripheral
output
enable
PDR read
(At read-modify-write)
Output latch
PDR write Pin
DDR write
PUL read
PUL write
Stop mode