Chapter 9 Buzzer Output Control Circuit; Buzzer Output Control Circuit Functions; Buzzer Output Control Circuit Configuration; Buzzer Output Control Circuit Block Diagram - NEC PD78081(A) User Manual

9.1 Buzzer Output Control Circuit Functions

The buzzer output control circuit outputs 1.2 kHz, 2.4 kHz, 4.9 kHz, or 9.8 kHz frequency square waves. The buzzer
frequency selected with timer clock select register 2 (TCL2) is output from the BUZ/P36 pin.
Follow the procedure below to output the buzzer frequency.
(1) Select the buzzer output frequency with bits 5 to 7 (TCL25 to TCL27) of TCL2.
(2) Set the P36 output latch to 0.
(3) Set bit 6 (PM36) of port mode register 3 to 0 (Set to output mode).
Caution Buzzer output cannot be used when setting P36 output latch to 1.

9.2 Buzzer Output Control Circuit Configuration

The buzzer output control circuit consists of the following hardware.
Control register
9
f /2
XX
10
f /2
XX
11
f /2
XX
TCL27 TCL26 TCL25
Timer Clock Select Register 2

CHAPTER 9 BUZZER OUTPUT CONTROL CIRCUIT

CHAPTER 9 BUZZER OUTPUT CONTROL CIRCUIT
Table 9-1. Buzzer Output Control Circuit Configuration
Item
Timer clock select register 2 (TCL2)
Port mode register 3 (PM3)
Figure 9-1. Buzzer Output Control Circuit Block Diagram
3
Internal Bus
Configuration
P36
Output Latch
BUZ/P36
PM36
Port Mode Register 3
115