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Timer_B Operation
Use of the Continuous Mode
The continuous mode can be used to generate independent time intervals and
output frequencies. Each time an interval is completed, an interrupt is
generated. The next time interval is added to the TBCLx latch in the interrupt
service routine. Figure 12−6 shows two separate time intervals t
added to the capture/compare registers. The time interval is controlled by
hardware, not software, without impact from interrupt latency. Up to three
(Timer_B3) or 7 (Timer_B7) independent time intervals or output frequencies
can be generated using capture/compare registers.
Figure 12−6. Continuous Mode Time Intervals
TBR (max)
TBCL0a
0h
EQU0 Interrupt
EQU1 Interrupt
Time intervals can be produced with other modes as well, where TBCL0 is
used as the period register. Their handling is more complex since the sum of
the old TBCLx data and the new period can be higher than the TBCL0 value.
When the sum of the previous TBCLx value plus t
data, the old TBCL0 value must be subtracted to obtain the correct time
interval.
12-8
Timer_B
TBCL1b
TBCL0b
TBCL1a
t 0
t 0
t 1
TBCL1c
TBCL0d
TBCL0c
TBCL1d
t 0
t 1
t 1
is greater than the TBCL0
x
and t
being
0
1
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