MULTIJUNCTION TIMERS
10.4 TIO (Input/Output-Related 16-Bit Timer)
10
10.4.11 Operation in TIO PWM Output Mode
(1) Outline of TIO PWM output mode
In PWM output mode, the timer uses two reload registers to generate a waveform with a given duty cycle.
When the timer is enabled (by writing to the enable bit in software or by external input) after setting the initial
values in the reload 0 and reload 1 registers, the counter is loaded with the reload 0 register value and starts
counting down synchronously with the count clock. The first time the counter underflows, it is loaded with the
reload 1 register value and continues counting. Thereafter, the counter is loaded with the reload 0 and reload
1 register values alternately each time an underflow occurs. The (reload 0 register set value + 1) and (reload
1 register set value + 1) respectively are effective as count values. The timer stops at the same time count is
disabled by writing to the enable bit (and not in synchronism with PWM output period).
The F/F output waveform in PWM output mode is inverted (F/F output level changes from low to high or vice
versa) when the counter starts counting and each time it underflows. An interrupt request can be generated
when the counter underflows every other time (second time, fourth time and so on) after being enabled.
Note that TIO’s PWM output mode does not have the count correction function.
Enabled
(by writing to the enable bit
or by external input)
Underflow
(first time)
Underflow
(second time)
Count clock
Enable bit
Count down from
Count down from
Count down from
the reload 1
register set value
the reload 0
the reload 1
register set value
register set value
H'FFFF
H'(C000-1)
H'C000
Undefined
value
H'(A000-1)
H'A000
H'A000
H'(A000-1)
Counter
H'0000
Reload 0 register
Reload 1 register
H'A000
H'C000
F/F output
Data inverted by
enable
Data inverted by
underflow
Data inverted by
underflow
TIO interrupt request
due to underflow
PWM output period
Note: • This diagram does not show detailed timing information.
Figure 10.4.9 Typical Operation in PWM Output Mode
32180 Group User’s Manual (Rev.1.0)
10-117
RENESAS [ RENESAS TECHNOLOGY CORP ]
