sh66k51a SinoWealth Micro-Electronics Corp. Ltd, sh66k51a Datasheet - Page 20

• Manufacturer Part Number: sh66k51a
• Description: 2k 4-bit Micro-controller With Lcd Driver
• Manufacturer: SinoWealth Micro-Electronics Corp. Ltd

8. Base Timer
The MCU has a base timer that is shared with the warm-up timer and the clock source is base timer prescaler output pulse
(scaled from OSC clock, Crystal 32.768kHz or RC 131kHz). After MCU is reset, it counts at every clock-input signal. When
it counts to $FF, right after next clock input, counter counts to $00 and generates an overflow. This causes the interrupt flag
of base timer to be set to “1”. Therefore, the base timer can function as an interval timer periodically, generating overflow
output as every 256th clock signal input.
The timer accepts 4096Hz or 16kHz clock, and base timer generates an accurate timing interrupt. The program for accurate
timing can reset this base time prescaler.
This clock-input source is selected by BTM register.
Address
$03
BTM.1
0
0
1
1
BTM.3
Bit3
1
Else states
32.768kHz
131kHz
or
BTM.2
Bit2
0
/8
BTM.0
0
1
0
1
4096/16kHz
BTM.1
Bit1
X
X
/1
BTM.0
/4
Bit0
4Bit Scaler
X
X
MPX
/8
/16
Prescaler Ratio
R/W
R/W Base timer mode register
R/W
R/W Enable the base timer
20
/16
Disable the base timer, clear base timer counters
and keep them as $00
/1
/4
/8
8 Bit base timer counter
reset
Remarks
Clock Source
f
f
f
OSC
f
OSC
OSC
OSC
/128
/32
/64
/8
SH66K51A