Microcontrollers Data Sheet

I/O Registers
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor 229
CHxF — Channel x Flag Bit
When channel x is an input capture channel, this read/write bit is set when an active edge occurs on
the channel x pin. When channel x is an output compare channel, CHxF is set when the value in the
TIMA counter registers matches the value in the TIMA channel x registers.
When CHxIE = 1, clear CHxF by reading TIMA channel x status and control register with CHxF set,
and then writing a 0 to CHxF. If another interrupt request occurs before the clearing sequence is
complete, then writing 0 to CHxF has no effect. Therefore, an interrupt request cannot be lost due to
inadvertent clearing of CHxF.
Reset clears the CHxF bit. Writing a 1 to CHxF has no effect.
1 = Input capture or output compare on channel x
0 = No input capture or output compare on channel x
CHxIE — Channel x Interrupt Enable Bit
This read/write bit enables TIMA CPU interrupts on channel x.
Reset clears the CHxIE bit.
1 = Channel x CPU interrupt requests enabled
0 = Channel x CPU interrupt requests disabled
Register Name and Address: TASC0 — $0013
Bit 7654321Bit 0
Read: CH0F
CH0IE MS0B MS0A ELS0B ELS0A TOV0 CH0MAX
Write: 0
Reset:00000000
Register Name and Address: TASC1 — $0016
Bit 7654321Bit 0
Read: CH1F
CH1IE
0
MS1A ELS1B ELS1A TOV1 CH1MAX
Write: 0 R
Reset:00000000
Register Name and Address: TASC2 — $0019
Bit 7654321Bit 0
Read: CH2F
CH2IE MS2B MS2A ELS2B ELS2A TOV2 CH2MAX
Write: 0
Reset:00000000
Register Name and Address: TASC3 — $001C
Bit 7654321Bit 0
Read: CH3F
CH3IE
0
MS3A ELS3B ELS3A TOV3 CH3MAX
Write: 0 R
Reset:00000000
R= Reserved
Figure 16-8. TIMA Channel Status
and Control Registers (TASC0–TASC3)