UPD75518 NEC, UPD75518 Datasheet - Page 68

• Manufacturer Part Number: UPD75518
• Description: 4 BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC

68
(3) Clock mode register
The clock mode register (WM) is an 8-bit register that controls the clock timer, and that is set with an
8-bit memory manipulation instruction. Fig. 4-23 shows the format.
The generation of a RESET signal clears all bits to 0.
Example
Address
F98H
Use the main system clock (4.19 MHz) for setting time, and enable buzzer output.
CLR1
MOV
MOV
WM7
7
MBE
XA, #84H
WM, XA
6
0
Fig. 4-23 Format of the Clock Mode Register
5
0
WM0
WM1
WM2
WM7
Count clock (fW) selection bit
Operation mode selection bit
Clock operation enable/disable bit
BUZ output enable/disable bit
4
0
; Set WM
0
1
0
1
0
1
0
1
3
0
Selects divided system clock output:
Selects subsystem clock: f
Normal clock mode (
Advanced clock mode (
Disables clock operation (clears the frequency dividing circuit)
Enables clock operation
Disables BUZ output
Enables BUZ output
WM2
2
WM1
1
WM0
2
f
0
W
14
f
2
W
: sets IRQW at 0.5 s)
7
XT
: sets IRQW at 3.91 ms)
Symbol
WM
128
f
X
PD75518(A)