Buzzer Output Operation - NEC mPD789426 Series User Manual

6.4.5 Buzzer output operation

The buzzer frequency is set using buzzer output control register 90 (BZC90) based on the count clock selected
with TCL901 and TCL900 of TMC90 (source clock). A square wave of the set buzzer frequency is output.
Table 6-4 shows the buzzer frequency.
Set the 16-bit timer as follows to use it for buzzer output:
• Set P21 to output mode (PM21 = 0).
• Reset output latch of P21 to 0.
• Set a count clock using TCL901 and TCL900.
• Set BZC90 as shown in Figure 6-12.
Figure 6-12. Settings of Buzzer Output Control Register 90 for Buzzer Output Operation
BZC90 0 0
BCS902 BCS901 BCS900
0 0
0 0
0 1
0 1
1 0
1 0
1 1
1 1
Remarks 1. f : Main system clock oscillation frequency
X
2. f : Subsystem clock oscillation frequency
XT
3. The parenthesized values apply to operation at f
128
CHAPTER 6 16-BIT TIMER
BCS902 BCS901 BCS900 BZOE90
0 0 0/1 0/1
Table 6-4. Buzzer Frequency of 16-Bit Timer
2
fcl = f /2
X
4
0 fcl/2 (78.1 kHz)
5
1 fcl/2 (39.1 kHz)
8
0 fcl/2 (4.88 kHz)
9
1 fcl/2 (2.44 kHz)
10
0 fcl/2 (1.22 kHz)
11
1 fcl/2 (610 Hz)
12
0 fcl/2 (305 Hz)
13
1 fcl/2 (153 Hz)
User's Manual U15075EJ1V0UM00
0/1 1
Enables buzzer output
Setting of buzzer frequency (see Table 6-4)
Buzzer Frequency
6
fcl = f /2
X
4 4
fcl/2 (4.88 kHz) fcl/2
5 5
fcl/2 (2.44 kHz) fcl/2
8 8
fcl/2 (305 Hz) fcl/2
9 9
fcl/2 (153 Hz) fcl/2
10 10
fcl/2 (76 Hz) fcl/2
11 11
fcl/2 (38 Hz) fcl/2
12 12
fcl/2 (19 Hz) fcl/2
13 13
fcl/2 (10 Hz) fcl/2
= 5.0 MHz or f
X
7
fcl = f /2 fcl = f
X
4
(2.44 kHz) fcl/2 (2.05 kHz)
5
(1.22 kHz) fcl/2 (1.02 kHz)
8
(153 Hz) fcl/2 (128 Hz)
9
(76 Hz) fcl/2 (64 Hz)
10
(38 Hz) fcl/2 (32 Hz)
11
(19 Hz) fcl/2 (16 Hz)
12
(10 Hz) fcl/2 (8 Hz)
13
(5 Hz) fcl/2 (4 Hz)
= 32.768 kHz.
XT
XT