MITSUBISHI MICROCOMPUTERS
M37274EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
Set “2816” to DA-L register.
Set “2C16” to DA-H register.
b7 b6 b5 b4 b3 b2 b1 b0
b7 b6 b5 b4 b3 b2 b1 b0
[DA-H
register]
D
L
D
H
0
1
0
1
0
0
0
0
1
0
1
1
0
0
[DA-L register]
Undefined
At writing of DA-L
At writing of DA-L
b13
b6 b5
b0
[DA latch]
0
0
1
0
1
1
0
0
1
0
1
0
0
0
These bits decide “H” level area of
fundamental waveform.
These bits decide smaller interval “tm” in which “H” leval
area is [“H” level area of fundamental waveform + τ ].
Minimum
resolution bit
width 0.25 µs
“H” level area of
fundamental waveform
High-order 8-bit
value of DA latch
✕
=
Fundamental
waveform
Waveform of smaller interval “tm” specified by low-order 6 bits
0.25 µs ✕44
0.25 µs ✕45
0.25 µs
14-bit
PWM output
14-bit
PWM output
2C 2B 2A … 03 02 01 00
2C 2B 2A … 03 02 01 00
8-bit
counter
8-bit
counter
…
…
…
…
D6 D5 D4 D3 02 01 00
FF FE FD
D6 D5 D4 D3
02 01 00
FF FE FD
Fundamental waveform of smaller interval
“tm” which is not specified by low-order 6
bits is not changed.
0.25 µs ✕44
τ = 0.25 µs
14-bit PWM output
t0
t1
t2
t3
t4
t
5
t59
t60
t61
t62
t63
Low-order 6-bit output
of DA latch
Repeat period
T = 4096 µs
Fig. 24. 14-bit PWM Output Example (f(XIN) = 8MHz)
31
RENESAS [ RENESAS TECHNOLOGY CORP ]
