Datasheet

Pulse-Width Modulator (PWM)
M68HC12B Family Data Sheet, Rev. 9.1
132 Freescale Semiconductor
11.2.7 PWM Scale Register 1
Read: Anytime
Write: Anytime
A write causes the scaler counter PWSCNT1 to load the PWSCAL1 value unless it is in special mode with
DISCAL = 1 in the PWTST register.
PWM channels 2 and 3 can select clock S1 (scaled) as its input clock by setting the control bit PCLK2
and PCLK3 respectively. Clock S1 is generated by dividing clock B by the value in the PWSCAL1 register
plus one and dividing again by two. When PWSCAL1 = $FF, clock B is divided by 256 then divided by two
to generate clock S1.
11.2.8 PWM Scale Counter 1 Value
Read: Anytime
PWSCNT1 is a down-counter that, upon reaching $00, loads the value of PWSCAL1.
Address: $0046
Bit 7654321Bit 0
Read:
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Write:
Reset:00000000
Figure 11-10. PWM Scale Register 1 (PWSCAL1)
Address: $0047
Bit 7654321Bit 0
Read: Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Write:
Reset:00000000
= Unimplemented
Figure 11-11. PWM Scale Counter 1 Value (PWSCNT1)