PWM_CH_SIZE
#define PWM_CWORD_MSB(ch) (0x08 + ((ch) * PWM_CH_SIZE))
#define PWM_CWORD_LSB(ch) (0x0c + ((ch) * PWM_CH_SIZE))
#define PWM_ON(ch) (0x18 + ((ch) * PWM_CH_SIZE))
#define PWM_PERIOD(ch) (0x1c + ((ch) * PWM_CH_SIZE))