M38517F8FP Renesas Electronics America, M38517F8FP Datasheet - Page 42

• Manufacturer Part Number: M38517F8FP
• Description: MCU 8-Bit 740 CISC 32KB Flash 5V 42-Pin SSOP
• Manufacturer: Renesas Electronics America

Specifications of M38517F8FP

• Package: 42SSOP
• Family Name: 740
• Maximum Speed: 8 MHz
• Ram Size: 1 KB
• Program Memory Size: 32 KB
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Program Memory Type: Flash
• Number Of Programmable I/os: 34
• Interface Type: I2C-BUS
• On-chip Adc: 5-chx10-bit
• Operating Temperature: -20 to 85 °C
• Number Of Timers: 4

3851 Group
PULSE WIDTH MODULATION (PWM)
The 3851 group (built-in 24 KB or more ROM) has a PWM func-
tion with an 8-bit resolution, based on a signal that is the clock
input X
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 X (n+1) / f(X
Output pulse “H” term = PWM period X m / 255
Fig. 41 Block diagram of PWM function
Rev.1.01
(X
CIN
IN
= 31.875 X (n+1) s
(when f(X
= 0.125 X (n+1) X m s
or that clock input divided by 2.
(when f(X
at low-speed mode)
Oct 15, 2003
(Built-in 24 KB or more ROM)
IN
IN
) = 8 MHz,count source selection bit = “0”)
) = 8 MHz,count source selection bit = “0”)
X
IN
page 40 of 89
D a t a b u s
IN
1 / 2
)
“ 0 ”
“1”
Count source
selection bit
4
prescaler pre-latch
. Set the PWM
P W M p r e s c a l e r
prescaler latch
PWM
PWM
T r a n s f e r c o n t r o l c i r c u i t
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
PWM register
register latch
P W M o u t p u t
P W M
PWM
m: Contents of PWM register
n : Contents of PWM prescaler
T : PWM period (when f(X
source selection bit = “0”)
3 1 . 8 7 5
P o r t P 4
T = [31.875
2 5 5
m
4
l a t c h
P W M e n a b l e b i t
( n + 1 )
IN
) = 8 MHz, count
(n+1)] s
s
P o r t P 4
4