M37220M3-010SP MITSUBISHI [Mitsubishi Electric Semiconductor], M37220M3-010SP Datasheet - Page 19

• Manufacturer Part Number: M37220M3-010SP
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER with ON-SCREEN DISPLAY CONTROLLER?
• Manufacturer: MITSUBISHI [Mitsubishi Electric Semiconductor]

PWM OUTPUT FUNCTION
The M37220M3-XXXSP is equipped with a 14-bit PWM (DA) and six
8-bit PWMs (PWM0–PWM5). DA has a 14-bit resolution with the
minimum resolution bit width of 0.25 s (for f(X
repeat period of 4096 s. PWM0–PWM5 have the same circuit struc-
ture and an 8-bit resolution with minimum resolution bit width of 4 s
(for f(X
Figure 13 shows the PWM block diagram. The PWM timing generat-
ing circuit applies individual control signals to PWM0–PWM5 using
f(X
(1) Data Setting
When outputting DA, first set the high-order 8 bits to the DA-H regis-
ter (address 00CE
(address 00CF
data in the PWMi register (i means 0 to 5; addresses 00D0
00D4
(2) Transmitting Data from Register to PWM circuit
Data transfer from the 8-bit PWM register to 8-bit PWM circuit is
executed at writing data to the register.
The signal output from the 8-bit PWM output pin corresponds to the
contents of this register.
Also, data transfer from the DA register (addresses 00CE
00CF
DA-L register (address 00CF
(address 00CE
it is possible to confirm the data being output from the D-A output pin
by reading the DA register.
(3) Operating of 8-bit PWM
The following is the explanation about PWM operation.
At first, set the bit 0 of PWM output control register 1 (address 00D5
to “0” (at reset, bit 0 is already set to “0” automatically), so that the
PWM count source is supplied.
PWM0–PWM5 are also used as pins P0
PWM0–PWM5, set the corresponding bits of the port P0 direction
register to “1” (output mode). And select each output polarity by bit 3
of the PWM output control register 2(address 00D6
bits 2 to 7 of the PWM output control register 1 to “1” (PWM output).
The PWM waveform is output from the PWM output pins by setting
these registers.
Figure 14 shows the 8-bit PWM timing. One cycle (T) is composed
of 256 (2
each bit (bits 0 to 7) are output inside the circuit during 1 cycle. Refer
to Figure 14 (a). The 8-bit PWM outputs waveform which is the logi-
cal sum (OR) of pulses corresponding to the contents of bits 0 to 7 of
the 8-bit PWM register. Several examples are shown in Figure 14
(b). 256 kinds of output (“H” level area: 0/256 to 255/256) are se-
lected by changing the contents of the PWM register. A length of
entirely “H” output cannot be output, i.e. 256/256.
IN
) divided by 2 as a reference signal.
16
16
IN
, 00F6
) to the 14-bit PWM circuit is executed at writing data to the
) = 8 MHz) and repeat period of 1024 s.
8
) segments. The 8 kinds of pulses relative to the weight of
16
16
16
).
). When outputting PWM0–PWM5, set 8-bit output
) means reading this transferred data. Accordingly,
16
), then the low-order 6 bits to the DA-L register
16
). Reading from the DA-H register
0
–P0
IN
5
) = 8 MHz) and a
respectively. For
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER
16
). Then, set
16
16
and
16
to
)
(4) Operating of 14-bit PWM
As with 8-bit PWM, set the bit 0 of the PWM output control register 1
(address 00D5
cally), so that the PWM count source is supplied. Next, select the
output polarity by bit 2 of the PWM output control register 2 (address
00D6
setting bit 1 of the PWM output control register 1 to “0” (at reset, this
bit already set to “0” automatically) to select the DA output.
The output example of the 14-bit PWM is shown in Figure 15.
The 14-bit PWM divides the data of the DA latch into the low-order 6
bits and the high-order 8 bits.
The fundamental waveform is determined with the high-order 8-bit
data “D
fundamental waveform) is output every short area of “t” = 256 =
64 s ( is the minimum resolution bit width of 0.25 s). The “H” level
area increase interval (t
“D
longer by than that of other smaller intervals in PWM repeat period
“T” = 64t. Thus, a rectangular waveform with the different “H” width is
output from the D-A pin. Accordingly, the PWM output changes by
unit pulse width by changing the contents of the DA-H and DA-L
registers. A length of entirely “H” output cannot be output, i. e. 256/
256.
(5) Output after Reset
At reset, the output of port P0
and the contents of the PWM register and the PWM circuit are unde-
fined. Note that after reset, the PWM output is undefined until setting
the PWM register.
L
.” The “H” level are of smaller intervals “t
16
). Then, the 14-bit PWM outputs from the D-A output pin by
H
.” A “H” level area with a length
16
) to “0” (at reset, bit 0 is already set to “0” automati-
with ON-SCREEN DISPLAY CONTROLLER
MITSUBISHI MICROCOMPUTERS
m
) is determined with the low-order 6-bit data
M37220M3-XXXSP
0
–P0
5
is in the high-impedance state,
m
” shown in Table 2 is
D
H
(“H” level area of
19