Motorola DSP56301 - Manual (Page 277)

Operating Modes
Triple Timer Module 9 -15
Figure 9-11. Pulse Width Measurement Mode, TRM = 1
Figure 9-12. Pulse Width Measurement Mode, TRM = 0
Mode 4 (internal clock): TRM = 1
N = write preload
M = write compare
TE
Clock
(CLK/2 or prescale CLK)
TLR
TCR
Counter
first event
M
0 N N + 1 M
N + 1
N
Interrupt Service
reads TCR; width
NOTE: If INV = 1, a 1-to-0 edge on TIO loads the counter, and a 0-to-1 edge on TIO
TCF (Compare Interrupt if TCIE = 1)
TIO pin
width being measured
stops the counter and loads TCR with the count.
= M - N clock
periods
Next 0-to-1 edge
on TIO loads
counter and
process repeats
Mode 4 (internal clock): TRM = 1
N = write preload
M = write compare
TE
Clock
(CLK/2 or prescale CLK)
TLR
TCR
Counter
first event
M
0 N N + 1 M
N + 1
N
Interrupt Service
reads TCR for
NOTE: If INV = 1, a 1-to-0 edge on TIO loads the counter, and a 0-to-1 edge on TIO
TCF (Compare Interrupt if TCIE = 1)
TIO pin
width being measured
stops the counter and loads TCR with the count.
accumulated width
of M - N clock periods.
Next 0-to-1 edge
on TIO starts
counter from current
count and process
repeats. Overflow
may occur (TOF = 1).