HD6473847RHV Datasheet, PDF (343/546 Pages) Renesas Technology Corp – Renesas 8-Bit Single-Chip Microcomputer H8 Family / H8/300L Super Low Power Series

Section 11 10-Bit PWM
11.4 Operation
11.4.1 Operation
When using the 10-bit PWM, set the registers in this sequence:
1. Set the PWM2 and/or PWM1 bits in port mode register 9 (PMR9) to 1 to set the P91/PWM2
pin or P90/PWM1 pin, or both, to function as PWM output pins.
2. Set the PWCR0 and PWCR1 bits in PWCR to select a conversion period of either. On the
H8/38104 Group, the output format is selected using the PWCR2 bit. Refer to section 9.4,
Asynchronous Event Counter (AEC), for information on how to select event counter PWM
(PWM incorporating AEC), one of the two available output formats.
3. Set the output waveform data in PWDRU and PWDRL. Be sure to write byte data first to
PWDRL and then to PWDRU. When the data is written in PWDRU, the contents of these
registers are latched in the PWM waveform generator, and the PWM waveform generation
data is updated in synchronization with internal signals.
One conversion period consists of four pulses, as shown in figure 11.2. The total high-level width
during this period (T_H) corresponds to the data in PWDRU and PWDRL. This relation can be
expressed as follows:
T_H = (data value in PWDRU and PWDRL + 4) × tφ/2
where tφ is the period of PWM clock input: 1/φ (PWCR1 = 0, PWCR0 = 0), 2/φ (PWCR1 = 0,
PWCR0 = 1), 4/φ (PWCR1 = 1, PWCR0 = 0), or 8/φ (PWCR1 = 1, PWCR0 = 1).
If the data value in PWDRU and PWDRL is from H'FFFC to H'FFFF, the PWM output stays high.
When the data value is H'FC3C, T_H is calculated as follows:
T_H = 64 × tφ/2 = 32 × tφ
Rev. 7.00 Mar. 08, 2010 Page 311 of 510
REJ09B0024-0700