h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 298

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 9 8-Bit PWM Timers [H8S/2138 Group]
9.2
9.2.1
PWSL is an 8-bit readable/writable register used to select the PWM timer input clock and the
PWM data register.
PWSL is initialized to H'20 by a reset, and in the standby modes, watch mode, subactive mode,
subsleep mode, and module stop mode.
Bits 7 and 6—PWM Clock Enable, PWM Clock Select (PWCKE, PWCKS): These bits,
together with bits PWCKA and PWCKB in PCSR, select the internal clock input to TCNT in the
PWM timer.
Bit 7
PWCKE
0
1
The PWM resolution, PWM conversion period, and carrier frequency depend on the selected
internal clock, and can be found from the following equations.
Thus, with a 20-MHz system clock ( ), the resolution, PWM conversion period, and carrier
frequency are as shown below.
Rev. 4.00 Jun 06, 2006 page 244 of 1004
REJ09B0301-0400
Bit
Initial value
Read/Write
Resolution (minimum pulse width) = 1/internal clock frequency
PWM conversion period = resolution
Carrier frequency = 16/PWM conversion period
PWSL
Register Descriptions
PWM Register Select (PWSL)
Bit 6
PWCKS
—
0
1
PWCKE
R/W
7
0
Bit 2
PWCKB
—
—
0
1
PWCKS
R/W
6
0
PCSR
Bit 1
PWCKA
—
—
0
1
0
1
—
—
5
1
256
—
—
4
0
Description
Clock input is disabled
/2 is selected
/4 is selected
/8 is selected
/16 is selected
(system clock) is selected
RS3
R/W
3
0
RS2
R/W
2
0
RS1
R/W
1
0
(Initial value)
RS0
R/W
0
0