Datasheet

Chapter 11 Pulse Width Modulator with Fault Protection (PMF15B6C) Module
MC9S12E256 Data Sheet, Rev. 1.10
Freescale Semiconductor 373
channel. In a complementary channel operation the even OUTCTL bit is used to enable software output
control for the pair. But the OUTCTL bits must be switched in pairs for proper operation. The OUTCTLx
and OUTx bits are in the PWM output control register.
NOTE
During software output control, TOPNEG and BOTNEG still control output
polarity. It will take up to 3 clock cycles to see the effect of output control
on the PWM output pins.
In independent PWM operation, setting or clearing the OUTx bit activates or deactivates the PWMx
output.
In complementary channel operation, the even-numbered OUTx bits replace the PWM generator outputs
as inputs to the deadtime generators. Complementary channel pairs still cannot be active simultaneously,
and the deadtime generators continue to insert deadtime in both channels of that pair, whenever an even
OUTx bit toggles. Even OUTx bits control the top PWM signals while the odd OUTx bits control the
bottom PWM signals with respect to the even OUTx bits. Setting the odd OUTx bit makes its
corresponding PWMx the complement of its even pair, while clearing the odd OUTx bit deactivates the
odd PWMx.
Setting the OUTCTLx bits do not disable the PWM generators and current status sensing circuitry. They
continue to run, but no longer control the output pins. When the OUTCTLx bits are cleared, the outputs of
the PWM generator become the inputs to the deadtime generators at the beginning of the next PWM cycle.
Software can drive the PWM outputs even when PWM enable bit (PWMEN) is set to zero.
NOTE
Avoid an unexpected deadtime insertion by clearing the OUTx bits before
setting and after clearing the OUTCTLx bits.