123
CHAPTER 7 8-BIT PWM TIMER
■
PWM timer function
The PWM timer function has 8-bit resolution and can control the "H" and "L" width of one cycle.
•
As the resolution is 1/256, pulses can be output with duty ratio of between 0 and 99.6%.
•
The cycle of the PWM wave can be selected from four types.
•
The PWM timer can be used as a D/A converter by connecting the output to a low-pass filter.
Table 7.1-2 "Available PWM wave cycle for PWM timer function" lists the available PWM wave cycles
for the PWM timer function. Figure 7.1-1 "Example D/A converter configuration using PWM output and
low-pass filter" shows an example D/A converter configuration.
Figure 7.1-1 Example D/A converter configuration using PWM output and low-pass filter
Reference:
Interrupt requests are not generated during operation of the PWM function.
Table 7.1-2 Available PWM wave cycle for PWM timer function
1
2
3
4
Internal count clock
8-bit timer output cycle times
Count clock cycle
1 t
inst
2
4
t
inst
2
6
t
inst
2 t
inst
to 2
9
t
inst
2
3
t
inst
to 2
11
t
inst
2
6
t
inst
to 2
14
t
inst
PWM wave cycle
2
8
t
inst
2
12
t
inst
2
14
t
inst
2
9
t
inst
to 2
17
t
inst
2
11
t
inst
to 2
19
t
inst
2
14
t
inst
to 2
22
t
inst
t
inst
: Instruction cycle
Analog output waveform
PWM output waveform
PWM pin
PWM output
R
C
Analog output (Va)
Tr
Va
Vcc
TH
TL
T
Va
t
Vcc
0
The relationship between the analog output voltage
and PWM output waveform is:
Va/Vcc = T
H
/T
Tr is the time taken for the output to stabilize.
Summary of Contents for MB89950 Series
Page 2: ......
Page 3: ...FUJITSU LIMITED F2MC 8L 8 BIT MICROCONTROLLER MB89950 950A Series HARDWARE MANUAL ...
Page 4: ......
Page 10: ...vi ...
Page 34: ...20 CHAPTER 2 HANDLING DEVICES ...
Page 134: ...120 CHAPTER 6 WATCHDOG TIMER ...
Page 236: ...222 CHAPTER 10 UART ...
Page 276: ...262 CHAPTER 12 LCD CONTROLLER DRIVER ...
Page 310: ...296 APPENDIX ...
Page 311: ...297 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Page 316: ...302 INDEX ...
Page 318: ......