Datasheet

Chapter 11 Pulse Width Modulator with Fault Protection (PMF15B6C) Module
MC9S12E256 Data Sheet, Rev. 1.10
Freescale Semiconductor 375
Figure 11-64. Setting OUTCTL with OUT0 Set in Complementary Mode
11.4.7 PWM Generator Loading
11.4.7.1 Load Enable
The load okay bit, LDOK, enables loading the PWM generator with:
• A prescaler divisor—from the PRSC1 and PRSC0 bits in PWM control register
• A PWM period—from the PWM counter modulus registers
• A PWM pulse width—from the PWM value registers
LDOK prevents reloading of these PWM parameters before software is finished calculating them Setting
LDOK allows the prescaler bits, PMFMOD and PMFVALx registers to be loaded into a set of buffers. The
loaded buffers use the PWM generator at the beginning of the next PWM reload cycle. Set LDOK by
reading it when it is a logic zero and then writing a logic one to it. After loading, LDOK is automatically
cleared.
11.4.7.2 Load Frequency
The LDFQ3, LDFQ2, LDFQ1, and LDFQ0 bits in the PWM control register (PWMCTL) select an integral
loading frequency of one to 16-PWM reload opportunities. The LDFQ bits take effect at every PWM
reload opportunity, regardless the state of the load okay bit, LDOK. The half bit in the PWMCTL register
controls half-cycle reloads for center-aligned PWMs. If the half bit is set, a reload opportunity occurs at
the beginning of every PWM cycle and half cycle when the count equals the modulus. If the half bit is not
set, a reload opportunity occurs only at the beginning of every cycle. Reload opportunities can only occur
at the beginning of a PWM cycle in edge-aligned mode.
MODULUS = 4
PWM VALUE = 2
DEADTIME = 2
PWM0
PWM1
PWM0 WITH DEADTIME
PWM1 WITH DEADTIME
OUTCTL0
OUT0
PWM0
PWM1
OUT1