MC705P6A Motorola, MC705P6A Datasheet - Page 49

• Manufacturer Part Number: MC705P6A
• Description: Microcontrollers
• Manufacturer: Motorola

8.3.3 Timer Registers
The timer registers (TRH and TRL), shown in
16-bit counter. Reading TRH before reading TRL causes TRL to be latched until TRL is read. Reading
TRL after reading the timer status register clears the timer overflow flag (TOF). Writing to the timer
registers has no effect.
8.3.4 Alternate Timer Registers
The alternate timer registers (ATRH and ATRL), shown in
bytes of the 16-bit counter. Reading ATRH before reading ATRL causes ATRL to be latched until ATRL
is read. Reading ATRL has no effect on the timer overflow flag (TOF). Writing to the alternate timer
registers has no effect.
Freescale Semiconductor
Address:
Address:
Address:
Address:
To prevent interrupts from occurring between readings of ATRH and ATRL,
set the interrupt flag in the condition code register before reading ATRH,
and clear the flag after reading ATRL.
Reset:
Reset:
Reset:
Reset:
Read:
Read:
Write:
Write:
Write:
Write
Figure 8-5. Alternate Timer Registers (ATRH and ATRL)
TRH — $0018
TRL — $0019
ATRH — $001A
ATRL — $001B
ACRH7
TRH7
Bit 7
Bit 7
Bit 7
Bit 7
1
1
1
1
MC68HC705P6A Advance Information Data Sheet, Rev. 2.1
Figure 8-4. Timer Registers (TRH and TRL)
= Unimplemented
= Unimplemented
ACRH6
TRH6
6
1
6
1
6
1
6
1
ACRH5
TRH5
5
1
5
1
5
1
5
1
Figure
NOTE
ACRH4
TRH4
4
1
4
1
4
1
4
1
8-4, contains the current high and low bytes of the
Figure
ACRH3
TRH3
3
1
3
1
3
1
3
1
8-5, contain the current high and low
ACRH2
TRH2
2
1
2
1
2
1
2
1
ACRH1
TRH1
1
1
1
0
1
1
1
0
ACRH0
TRH0
Bit 0
Bit 0
Bit 0
Bit 0
Timer I/O Registers
1
0
1
0
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