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TIMER A
5.6 Pulse width modulation (PWM) mode
b7
b6
b5
b4
b3
<When operating as a 16-bit pulse width modulator>
(b15)
b7
<When operating as an 8-bit pulse width modulator>
(b15)
b7
Fig. 5.6.1 Structures of timer Ai mode registers and timer Ai registers in PWM mode
5–40
b2
b1
b0
1
1
1
Timer Ai mode register (i = 0 to 4) (Addresses 56
Bit
Operating mode select bits
0
1
2
Fix this bit to "1" in PWM mode.
3
Trigger select bits
4
5
16/8-bit PWM mode select bit
Count source select bits
6
7
(b8)
b0 b7
(b8)
b0 b7
7751 Group User's Manual
Bit name
b1 b0
1 1 : PWM mode
b4 b3
0 0 : Writing "1" to count start bit
0 1 : (TAi
grammable I/O port.)
1 0 : Falling edge of TAi
1 1 : Rising edge of TAi
0 : As a 16-bit pulse width modulator
1 : As an 8-bit pulse width modulator
b7 b6
0 0 : f
/f
2
4
0 1 : f
/f
16
1 0 : f
/f
64
1 1 : f
512
Timer A0 register (Addresses 47
b0
Timer A1 register (Addresses 49
Timer A2 register (Addresses 4B
Timer A3 register (Addresses 4D
Timer A4 register (Addresses 4F
Bit
15 to 0 These bits can be set to "0000
Assuming that the set value = n, the "H" level
width of the PWM pulse output from the
TAi
pin is expressed as follows:
OUT
f
: Frequency of count source (f
i
Timer A0 register (Addresses 47
b0
Timer A1 register (Addresses 49
Timer A2 register (Addresses 4B
Timer A3 register (Addresses 4D
Timer A4 register (Addresses 4F
Bit
These bits can be set to "00
7 to 0
Assuming that the set value = m, PWM
pulse's period output from the TAi
expressed as follows:
15 to 8
These bits can be set to "00
Assuming that the set value = n, the "H" level
width of the PWM pulse output from the
TAi
pin is expressed as follows:
OUT
n(m + 1)
f
i
f
: Frequency of count source (f
i
to 5A
)
16
16
Functions
At reset
pin functions as a pro-
IN
pin's input signal
IN
pin's input signal
IN
32
128
/f
1024
, 46
)
16
16
, 48
)
16
16
, 4A
)
16
16
, 4C
)
16
16
, 4E
)
16
16
Functions
At reset
" to "FFFE
."
16
Undefined
16
n
f
i
/f
, f
/f
, f
/f
, or f
/f
2
4
16
32
64
128
512
1024
, 46
)
16
16
, 48
)
16
16
, 4A
)
16
16
, 4C
)
16
16
, 4E
)
16
16
Functions
At reset
" to "FF
."
Undefined
16
16
pin is
OUT
8
(m + 1)(2
– 1)
f
i
" to "FE
."
Undefined
16
16
/f
, f
/f
, f
/f
, or f
/f
2
4
16
32
64
128
512
1024
RW
0
RW
0
RW
0
RW
0
RW
0
RW
0
RW
0
RW
0
RW
RW
WO
)
RW
WO
WO
)
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