Figure 11.3A Block Diagram Of P44/Bz Pin; Figure 11.3B Buzzer Output Register; Structure Of Buzzer Output - Fujitsu F2MC-8L MB89620 Series Hardware Manual

3
11.

Structure of Buzzer Output

This section describes the pin, pin block diagram, and register of the buzzer output.
n Buzzer Output Pin
The buzzer output uses the P44/BZ pin. The pin can function either as a hysteresis input and an
N-ch open-drain output port (P44) or as the buzzer output pin (BZ).
BZ: This pin outputs a buzzer square wave with the specified frequency.
Setting a buzzer output frequency in the buzzer output register (BZCR: BZ1, BZ0 = other
than "00
value.
n Block Diagram of Buzzer Output Pin
SPL: Pin state specification bit in the standby control register (STBC)
n Buzzer Output Register
BZCR (Buzzer register)
R/W: Readable and writable
— : Unused
X : Indeterminate
228
CHAPTER 11 BUZZER OUTPUT
") automatically sets the P44/BZ pin as the BZ pin regardless of the output latch
B
PDR
(Port data register)
PDR read
PDR read (for read-modify-write)
Output latch
PDR write
Stop mode (SPL = "1")

Figure 11.3a Block Diagram of P44/BZ Pin

Note: Pins with a pull-up resistor (optional) go to the "H" level during a reset or in stop mode
(SPL = "1").
Address Bit 7 Bit 6
000F — —
H

Figure 11.3b Buzzer Output Register

Buzzer output Buzzer output
enable signal
Bit 5 Bit 4 Bit 3 Bit 2
— — — —
Pull-up resistor
(optional)
Approx. 50 kΩ/5.0 V
Input buffer
Pin
P44/BZ
Output
Tr
Bit 1 Bit 0 Initial value
BZ1 BZ0 XXXXXX00
R/W R/W
B
MB89620 series