Renesas M32R/ECU Series

10
10-192
MULTIJUNCTION TIMERS
10.8 TOU (Output-Related 24-Bit Timer)
32180 Group User’s Manual (Rev.1.0)
10.8.17 0% or 100% Duty-Cycle Wave Output during PWM Output and Single-shot PWM
Output Modes
During PWM output or single-shot PWM output mode, if the value ‘FFFF’ is written to the reload 0 or reload 1
register, F/F output will not be inverted, making it possible to produce a 0% or 100% duty-cycle PWM output.
Because determination is made to see if the reload value is ‘FFFF’ during PWM output or single-shot PWM
output mode, following precautions must be observed.
(1) Because the counter counts one even when detecting 0% or 100% duty-cycle, one of the two reload
registers must have set in it one less than the intended value in order for a constant-cycle waveform to be
produced.
Example: If the desired output cycle is 10 counts
Cycle ratio 50% : 50% 80% : 20% 90% : 10% 100% : 0%
Count ratio 5 : 5 8 : 2 9 : 1 10 : 0
ƒRegister set values 0004 : 0004 0007 : 0001 0008 : 0000 0009 : FFFF
Because the counter counts n + 1, the values actually set in the
respective registers must be one less than the intended value.
(2) Because setting the value ‘FFFF’ in the reload register produces a 0% or 100% duty-cycle, it is impossible
to count the exact ‘FFFF.’
(3) Setting the value ‘FFFF’ in both reload 0 and reload 1 registers is inhibited.
(4) Writing the value ‘FFFF’ to the counter while in operation is inhibited.
(5) Even for a 0% or 100% duty-cycle, interrupt requests and startup registers to other timers are generated.
(6) Because a 0% or 100% duty-cycle needs to be determined when reloading the counter, there is a one
count clock equivalent delay before F/F is inverted and an interrupt or DMA transfer request is generated.
However, startup requests to other timers are not delayed.
0008: FFFF
The counter counts one without invert-
ing F/F output after detecting ‘FFFF.’
For this reason, the value to be set in the
register must be ‘0008’, and not ‘0009’.