m37516e6hp Renesas Electronics Corporation., m37516e6hp Datasheet - Page 42

• Manufacturer Part Number: m37516e6hp
• Description: Single-chip 8-bit Cmos Microcomputer
• Manufacturer: Renesas Electronics Corporation.

7516 Group
PULSE WIDTH MODULATION (PWM)
The 7516 group has a PWM function with an 8-bit resolution,
based on a signal that is the clock input X
vided by 2.
Data Setting
The PWM output pin also functions as port P4
period by the PWM prescaler, and set the “H” term of output pulse
by the PWM register.
If the value in the PWM prescaler is n and the value in the PWM
register is m (where n = 0 to 255 and m = 0 to 255) :
PWM period = 255
Output pulse “H” term = PWM period
Fig. 41 Block diagram of PWM function
Rev.1.01
( X
C I N
= 31.875
(when f(X
= 0.125
a t l o w - s p e e d m o d e )
(when f(X
Jul 01, 2003
IN
(n+1)
IN
) = 8 MHz,count source selection bit = “0”)
(n+1) s
) = 8 MHz,count source selection bit = “0”)
(n+1) / f(X
X
IN
m s
page 40 of 89
D a t a b u s
IN
1/2
)
“ 0 ”
m / 255
“ 1 ”
Count source
selection bit
IN
or that clock input di-
4
. Set the PWM
p r e s c a l e r p r e - l a t c h
P W M p r e s c a l e r
prescaler latch
PWM
P W M
Transfer control circuit
PWM Operation
When bit 0 (PWM enable bit) of the PWM control register is set to
“1”, operation starts by initializing the PWM output circuit, and
pulses are output starting at an “H”.
If the PWM register or PWM prescaler is updated during PWM
output, the pulses will change in the cycle after the one in which
the change was made.
Fig. 40 Timing of PWM period
r e g i s t e r p r e - l a t c h
P W M r e g i s t e r
register latch
PWM output
PWM
P W M
m : C o n t e n t s o f P W M r e g i s t e r
n : C o n t e n t s o f P W M p r e s c a l e r
T : P W M p e r i o d ( w h e n f ( X
s o u r c e s e l e c t i o n b i t = “ 0 ” )
3 1 . 8 7 5
T = [ 3 1 . 8 7 5
P o r t P 4
255
m
4
( n + 1 )
l a t c h
I N
P W M e n a b l e b i t
) = 8 M H z , c o u n t
( n + 1 ) ] s
s
Port P4
4