Lucent Technologies MN10285K - Manual (Page 99)

Timers
16-Bit Timer Setup Examples
Panasonic Semiconductor Development Company MN102H75K/F75K/85K/F85K LSI User Manual
98
Panasonic
6. Set the TM4NLD bit of the TM4MD register to 1 and the TM4EN bit to 0.
This enables TM4BC and the S-R flip-flop. This step ensures stable opera-
tion. If it is omitted, the binary counter may not count the first cycle. Do not
change any other operating modes during this step.
7. Set TM4NLD and TM4EN to 1. This starts the timer. Counting begins at the
start of the next cycle.
Timer 4 can output a single-phase PWM signal at any duty. You must select up
counting. Timer 4 does not operate in STOP mode, when B
OSC
is off. If you use
an external clock, it must be synchronized to B
OSC
.
In this procedure, you set the cycle (x’0001’ to x’FFFE’) in the TM4CA register
and the duty in the TM4CB register. When the contents of TM4BC match those
of the TM4CB register, the S-R flip-flop resets at the beginning of the next cycle.
Please note the following:
■ When -1
≤
TM4CB
<
TM4CA, TM4OA output is low during the 0 to
TM4CB + 1 cycles of the TM4CA + 1 cycle period and high during the
remainder of the cycles.
■ When TM4CA
≤
TM4CB
≤
x’FFFE, TM4OA output is always low.
■ When TM4BC = x’FFFF’, TM4OA output is always high.
The circuitry is configured so that there are no waveform errors, even when the
output is always high or always low. Counting begins after the TM4EN bit is set
in the TM4MD register.