7721 Datasheet, PDF (157/577 Pages) List of Unclassifed Manufacturers – H Bridge Power Module

TIMER A
8.6 Pulse width modulation (PWM) mode
8.6 Pulse width modulation (PWM) mode
In this mode, the timer continuously outputs pulses which have an arbitrary width. (Refer to “Table 8.6.1.”)
Timers A2 to A4 can be used in this mode. Figure 8.6.1 shows the structures of the timer Aj mode registers
and timer Aj registers in the PWM mode.
Table 8.6.1 Specifications of PWM mode
Item
Specifications
Count source
f2, f16, f64, or f512
Count operation
q Countdown (operating as an 8-bit or 16-bit pulse width modulator)
q Reload register’s contents are reloaded at rising edge of PWM pulse,
and counting continues.
q A trigger generated during counting does not affect the counting.
PWM period/“H” level width
<16-bit pulse width modulator>
(2¹⁶–1)
Period = _fi
[s]
n
“H” level width = _fi [s]
n : Timer Aj register’s set value
<8-bit pulse width modulator>
m : Timer Aj register low-order 8 bits’
Period =
(m + 1)(2⁸–1)
fin(m
+
[s]
1)
set value
n : Timer Aj register high-order 8
“H” level width =
fi
[s]
bits’ set value
Count start condition
q When a trigger is generated. (Note)
q Internal or external trigger can be selected by software.
Count stop condition
When the count start bit is cleared to “0.”
Interrupt request occurrence timing At falling edge of PWM pulse
TAjIN pin’s function
Programmable I/O port or trigger input
TAjOUT pin’s function
PWM pulse output
Read from timer Aj register
An undefined value is read out.
Write to timer Aj register
q While counting is stopped
When a value is written to the timer Aj register, it is written to both
of the reload register and counter.
q While counting is in progress
When a value is written to the timer Aj register, it is written only to
the reload register. (Transferred to the counter at the next reload
time.)
Note: The trigger is generated with the count start bit = “1.”
8–38
7721 Group User’s Manual