s908az32ag2cfue Freescale Semiconductor, Inc, s908az32ag2cfue Datasheet - Page 199

• Manufacturer Part Number: s908az32ag2cfue
• Description: M68hc08 Microcontrollers 8-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

18.8.2 TIMA Counter Registers
The two read-only TIMA counter registers contain the high and low bytes of the value in the TIMA counter.
Reading the high byte (TACNTH) latches the contents of the low byte (TACNTL) into a buffer. Subsequent
reads of TACNTH do not affect the latched TACNTL value until TACNTL is read. Reset clears the TIMA
counter registers. Setting the TIMA reset bit (TRST) also clears the TIMA counter registers.
18.8.3 TIMA Counter Modulo Registers
The read/write TIMA modulo registers contain the modulo value for the TIMA counter. When the TIMA
counter reaches the modulo value, the overflow flag (TOF) becomes set and the TIMA counter resumes
counting from $0000 at the next clock. Writing to the high byte (TAMODH) inhibits the TOF bit and
overflow interrupts until the low byte (TAMODL) is written. Reset sets the TIMA counter modulo
registers.
Freescale Semiconductor
Register Name and Address
Register Name and Address
Register Name and Address
Register Name and Address
Figure 18-6. TIMA Counter Modulo Registers (TAMODH and TAMODL)
If TACNTH is read during a break interrupt, be sure to unlatch TACNTL by
reading TACNTL before exiting the break interrupt. Otherwise, TACNTL
retains the value latched during the break.
Reset the TIMA counter before writing to the TIMA counter modulo registers.
Reset:
Reset:
Reset:
Reset:
Read:
Read:
Read:
Read:
Write:
Write:
Write:
Write:
Figure 18-5. TIMA Counter Registers (TACNTH and TACNTL)
BIT 15
BIT 15
BIT 7
BIT 7
Bit 7
Bit 7
Bit 7
Bit 7
R
R
R
0
0
1
1
BIT 14
BIT 14
BIT 6
BIT 6
R
R
6
0
6
0
6
1
6
1
= Reserved
MC68HC908AZ32A Data Sheet, Rev. 2
TACNTH — $0022
TACNTL — $0023
TAMODH — $0024
TAMODL — $0025
BIT 13
BIT 13
BIT 5
BIT 5
R
R
5
0
5
0
5
1
5
1
NOTE
NOTE
BIT 12
BIT 12
BIT 4
BIT 4
R
R
4
0
4
0
4
1
4
1
BIT 11
BIT 11
BIT 3
BIT 3
R
R
3
0
3
0
3
1
3
1
BIT 10
BIT 10
BIT 2
BIT 2
R
R
2
0
2
0
2
1
2
1
BIT 9
BIT 1
BIT 9
BIT 1
R
R
1
0
1
0
1
1
1
1
BIT 0
BIT 8
BIT 8
BIT 0
Bit 0
Bit 0
Bit 0
Bit 0
R
R
0
0
1
1
I/O Registers
199