w78l365a Winbond Electronics Corp America, w78l365a Datasheet - Page 14

• Manufacturer Part Number: w78l365a
• Description: 8-bit Microcontroller
• Manufacturer: Winbond Electronics Corp America

5.7
There are five pulse width modulated output channels to generate pulses of programmable length and
interval. The repetition frequency is defined by an 8-bit prescaler PWMP, which supplies the clock for
the counter. The prescaler and counter are common to both PWM channels. The 8-bit counter counts
modular 255 (0−254). The value of the 8-bit counter compared to the contents of five registers:
PWM0, PWM1, PWM2, PWM3 and PWM4. Provided the contents of either these registers is greater
than the counter value, the corresponding PWM0, PWM1, PWM2, PWM3 or PWM4 output is set
HIGH. If the contents of these registers are equal to, or less than the counter value, the output will be
LOW. The pulse-width-ratio is defined by the contents of the registers PWM0, PWM1, PWM2, PWM3
and PWM4. The pulse-width-ratio is in the range of 0 to 1 and may be programmed in increments of
1/255. ENPWM0, ENPWM1, ENPWM2, ENPWM3 and ENPWM4 bit will enable or disable PWM
output.
Buffered PWM outputs may be used to drive DC motors. The rotation speed of the motor would be
proportional to the contents of PWM0/1/2/3/4. The repetition frequency
output is given by:
Prescaler division factor = PWM + 1
PWMn high/low ratio of
Pulse Width Modulated Outputs (PWM)
f
pwm
REGISTER
P4xAL
P4xAH
=
ADDRESS BUS
2
×
READ
WRITE
1 (
+
P4 REGISTER
PWMP
P4.x
f
osc
REGISTER
P4xCMP0
P4xCMP1
)
PWMn =
×
255
EQUAL
Bit Length
Selectable
comparator
255
P4xCSINV
(
PWMn)
-
(PWMn)
- 14 -
P4xFUN0
P4xFUN1
W78LE365/W78L365A
P4.x INPUT DATA BUS
Publication Release Date: April 28, 2008
DATA I/O
RD/WR_CS
WR_CS
RD_CS
MUX 4->1
f
pwm
, at the PWM0/1/2/3/4
P4.x
PIN
Revision A8