Freescale Semiconductor MC68HC908MR32 - Manual (Page 140)

Pulse-Width Modulator for Motor Control (PWMMC)
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
140 Freescale Semiconductor
Figure 12-28. PWM Disabling in Automatic Mode
IIf prior to a vector fetch, the interrupt request latch is cleared by one of the actions listed, a CPU interrupt
will no longer be requested. A vector fetch does not alter the state of the PWMs, the FFLAGx event flag,
or FINTx.
NOTE
If the FFLAGx or FINTx bits are not cleared during the interrupt service
routine, the interrupt request latch will not be cleared.
12.6.1.3 Manual Mode
In manual mode, the PWM(s) are disabled immediately once a filtered fault condition is detected (logic
high). The PWM(s) remain disabled until software clears the corresponding FFLAGx event bit and a new
PWM cycle begins. In manual mode, the fault pins are grouped in pairs, each pair sharing common
functionality. A fault condition on pins 1 and 3 may be cleared, allowing the PWM(s) to enable at the start
of a PWM cycle regardless of the logic level at the fault pin. See
Figure 12-29 . A fault condition on pins 2
and 4 can only be cleared, allowing the PWM(s) to enable, if a logic low level at the fault pin is present at
the start of a PWM cycle. See
Figure 12-30 .
The function of the fault control and event bits is the same as in automatic mode except that the PWMs
are not re-enabled until the FFLAGx event bit is cleared by writing to the FTACKx bit and the filtered fault
condition is cleared (logic low).
Figure 12-29. PWM Disabling in Manual Mode (Example 1)
PWM(S) ENABLED PWM(S) ENABLED PWM(S) DISABLED (INACTIVE)
FILTERED FAULT PIN
PWM(S) ENABLED PWM(S) ENABLED PWM(S) DISABLED
FFLAGX CLEARED
FILTERED FAULT PIN 1 OR 3