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2.10.2 14-bit PWM (DA output)
The 14-bit PWM automatically outputs a PWM rectangular waveform from the D-A pin by writing high-order
8 bits of the output data to the DA-H register and the low-order 6 bits to the DA-L register. Data of the
DA-H register are transferred to the 14-bit PWM circuit when writing to the DA-L register.
The following explains the output operation of 14-bit PWM rectangular waveform (when f(X
The repeat cycle "T" (4,096 µ s) of output waveform is divided into 2
64 µ s). The "t" is further divided into the minimum resolution bit "τ" of 2
The HIGH duration of the fundamental waveform is determined by the high-order 8 bits "D
latch.
HIGH duration (time) = τ
Because the D
values are "0" to "255," the HIGH duration can be selected a total of 256.
H
The smaller interval "t
the DA latch. The t
Therefore, a rectangular waveform consisted of 2-kind waveforms with different HIGH duration are output
from pin D–A (a length of entirely HIGH output cannot be output).
Figure 2.10.3 shows the 14-bit PWM output example, Table 2.10.2 shows the relation between D
(m = "0" to "63").
Table 2.10.2 The relation between D
Low-order 6-bit data of DA register (D
MSB
0 0 0 0 0 0
0 0 0 0 0 1
0 0 0 0 1 0
0 0 0 0 1 1
0 0 0 1 0 0
0 0 0 1 0 1
0 0 0 1 1 0
:
0 0 1 0 0 0
:
0 1 0 0 0 0
:
1 0 0 0 0 0
:
1 0 1 0 0 0
:
1 1 1 1 1 1
D
(when f(X
H
" with a longer HIGH level area by "τ" is specified by the low-order 6 bits "D
m
is specified from among 64 smaller intervals (t
m
and t
L
Smaller intervals that HIGH duration is longer by τ
)
L
LSB
Nothing
m = 32
m = 16, 48
m = 16, 32, 48
m = 8, 24, 40, 56
m = 8, 24, 32, 40, 56
m = 8, 16, 24, 40, 48, 56
m = 4, 12, 20, 28, 36, 44, 52, 60
m = 2, 6, 10, 14, 18, ... 46, 50, 54, 58, 62
m = 1, 3, 5, 7, 9 ... 55, 57, 59, 61, 63
m = 1, 3, 5, 7, 9 ... 52, 55, 57, 59, 60, 61, 63
m = 1 to 63 ("0" is not included)
7220 Group User's Manual
FUNCTIONAL DESCRIPTION
) = 8 MHz, 0.25D
µ s)
IN
H
(
= "0" to "63")
m
m
t
(
= "0" to "63")
m
m
:
:
:
:
:
6
= 64 smaller interval "t" (t =
8
= 256 (τ = 0.25 µ s).
to t
).
0
63
2.10 PWM
) = 8 MHz).
IN
" of the DA
H
" of
L
and t
L
m
Number
0
1
2
3
4
5
6
:
8
:
16
:
32
:
40
:
63
2-65
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