NEC 78014Y Series, User Manual

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CHAPTER 13 BUZZER OUTPUT CONTROL CIRCUIT
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CHAPTER 13 BUZZER OUTPUT CONTROL CIRCUIT
13.1 Buzzer Output Control Circuit Functions
The buzzer output control circuit outputs a square wave with a frequency of either 2.4 kHz, 4.9 kHz, or 9.8 kHz.
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 (PM3) to 0 (Set to output mode).
Caution Buzzer output cannot be used if P36 output latch is set to 1.
13.2 Buzzer Output Control Circuit Configuration
The buzzer output control circuit consists of the following hardware.
Table 13-1. Buzzer Output Control Circuit Configuration
Item Configuration
Control register Timer clock select register 2 (TCL2)
Port mode register 3 (PM3)
Figure 13-1. Buzzer Output Control Circuit Block Diagram
f
X
/2 10
f
X
/2
11
f
X
/2
12
3
BUZ/P36
TCL27 TCL26 TCL25
P36
Output Latch
PM36
Timer Clock Select Register 2 Port Mode Register 3
Internal Bus
Selector