MC68711E20CFNE3 Datasheet, PDF (134/242 Pages) –

Timing Systems
OC1 is different from the other output compares in that a successful OC1 compare can affect any or all
five of the OC pins. The OC1 output action taken when a match is found is controlled by two 8-bit registers
with three bits unimplemented: the output compare 1 mask register, OC1M, and the output compare 1
data register, OC1D. OC1M specifies which port A outputs are to be used, and OC1D specifies what data
is placed on these port pins.
9.4.1 Timer Output Compare Registers
All output compare registers are 16-bit read-write. Each is initialized to $FFFF at reset. If an output
compare register is not used for an output compare function, it can be used as a storage location. A write
to the high-order byte of an output compare register pair inhibits the output compare function for one bus
cycle. This inhibition prevents inappropriate subsequent comparisons. Coherency requires a complete
16-bit read or write. However, if coherency is not needed, byte accesses can be used.
For output compare functions, write a comparison value to output compare registers TOC1–TOC4 and
TI4/O5. When TCNT value matches the comparison value, specified pin actions occur.
Register name: Timer Output Compare 1 Register (High) Address: $1016
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Write:
Reset: 1
1
1
1
1
1
1
1
Register name: Timer Output Compare 1 Register (Low) Address: $1017
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Write:
Reset: 1
1
1
1
1
1
1
1
Figure 9-8. Timer Output Compare 1 Register Pair (TOC1)
Register name: Timer Output Compare 2 Register (High) Address: $1018
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Write:
Reset: 1
1
1
1
1
1
1
1
Register name: Timer Output Compare 2 Register (Low) Address: $1019
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Write:
Reset: 1
1
1
1
1
1
1
1
Figure 9-9. Timer Output Compare 2 Register Pair (TOC2)
M68HC11E Family Data Sheet, Rev. 5.1
134
Freescale Semiconductor