mc908jl16 Freescale Semiconductor, Inc, mc908jl16 Datasheet - Page 79

• Manufacturer Part Number: mc908jl16
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

PS[2:0] — Prescaler Select Bits
6.9.2 TIM Counter Registers
The two read-only TIM counter registers contain the high and low bytes of the value in the TIM counter.
Reading the high byte (TCNTH) latches the contents of the low byte (TCNTL) into a buffer. Subsequent
reads of TCNTH do not affect the latched TCNTL value until TCNTL is read. Reset clears the TIM counter
registers. Setting the TIM reset bit (TRST) also clears the TIM counter registers.
If you read TCNTH during a break interrupt, be sure to unlatch TCNTL by reading TCNTL before exiting
the break interrupt. Otherwise, TCNTL retains the value latched during the break.
Freescale Semiconductor
These read/write bits select one of the seven prescaler outputs as the input to the TIM counter as
Table 6-2
shows. Reset clears the PS[2:0] bits.
Address: T1CNTH, $0021 and T2CNTH, $0031
Address: T1CNTL, $0022 and T2CNTL, $0032
Reset:
Reset:
Read:
Read:
Write:
Write:
PS2
0
0
0
0
1
1
1
1
Bit 15
Bit 7
Bit 7
Bit 7
0
0
Figure 6-5. TIM Counter Registers High (TCNTH)
Figure 6-6. TIM Counter Registers Low (TCNTL)
= Unimplemented
= Unimplemented
PS1
14
0
0
1
1
0
0
1
1
6
0
6
6
0
MC68HC908JL16 Data Sheet, Rev. 1.1
Table 6-2. Prescaler Selection
PS0
13
5
0
5
5
0
0
1
0
1
0
1
0
1
NOTE
12
4
0
4
4
0
Internal bus clock ÷ 16
Internal bus clock ÷ 32
Internal bus clock ÷ 64
T2CLK (for TIM2 only)
Internal bus clock ÷ 1
Internal bus clock ÷ 2
Internal bus clock ÷ 4
Internal bus clock ÷ 8
TIM Clock Source
11
3
0
3
3
0
10
2
0
2
2
0
1
9
0
1
1
0
Bit 0
Bit 8
Bit 0
Bit 0
0
0
I/O Registers
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