sh66k51a SinoWealth Micro-Electronics Corp. Ltd, sh66k51a Datasheet - Page 19

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

7. Timer0
The timer/counter has the following features:
- 8-bit up-counting timer/counter
- Automatic re-load counter
- 8-level prescaler
- Interrupt on overflow from $FF to $00
The following is a simplified timer block diagram.
The timers provide the following functions:
- Programmable interval timer function.
- Read counter value.
7.1. Timer0 Configuration and Operation
The Timer0 consist of an 8-bit write-only timer load
register (TL0L, TL0H) and an 8-bit read-only timer
counter (TC0L, TC0H). Each of them has low order digits
and high order digits. Writing data into the timer load
register (TL0L, TL0H) can initialize the timer counter.
7.2. Timer Mode Register
The timer can be programmed in several different prescalers by setting Timer Mode register (TM0).
The 8-bit counter prescaler overflow output pulses. The Timer Mode registers (TM0) are 3-bit registers used for the timer
control as shown in Table 1. These mode registers select the input pulse sources into the timer.
Table 1. Timer0 Mode Register ($02)
System
TM0.2
clock
0
0
0
0
1
1
1
1
TM0.1
TM.2
0
0
1
1
0
0
1
1
Prescaler
t
TM.1
osc
TM0.0
TM.0
0
1
0
1
0
1
0
1
SYNC
Prescaler Divide Ratio
COUNTER
8-BIT
/2
/2
/2
/2
/2
/2
/2
/2
11
9
7
5
3
2
1
0
19
The low-order digit should be written first, and then the
high-order digit. The timer counter is automatically loaded
with the contents of the load register when the high order
digit is written or counter counts overflow from $FF to $00.
Timer Load Register: Since the register H controls the
physical READ and WRITE operations.
Please follow these steps:
Write Operation:
Read Operation:
Low nibble first
High nibble to update the counter
High nibble first
Low nibble followed.
Load Reg. L
Clock Source
Latch Reg. L
System clock
System clock
System clock
System clock
System clock
System clock
System clock
System clock
8-bit timer counter
Load Reg. H
SH66K51A