Chapter 25 FlexPWM
MPC5602P Microcontroller Reference Manual, Rev. 4
Freescale Semiconductor
701
Figure 25-50. Fault decoder for PWMA
25.8.13 Fault pin filter
Each fault pin has a programmable filter that can be bypassed. The sampling period of the filter can be
adjusted with the FILT_PER field of the FFILTx register. The number of consecutive samples that must
agree before an input transition is recognized can be adjusted using the FILT_CNT field of the same
register. Setting FILT_PER to all 0 disables the input filter for a given FAULTx pin.
Upon detecting a logic 0 on the filtered FAULTx pin (or a logic 1 if FLVLx is set), the corresponding
FFPINx and fault flag, FFLAGx, bits are set. The FFPINx bit remains set as long as the filtered FAULTx
pin is zero. Clear FFLAGx by writing a logic 1 to FFLAGx.
If the FIEx, FAULTx pin interrupt enable bit is set, the FFLAGx flag generates a CPU interrupt request.
The interrupt request latch remains set until:
•
Software clears the FFLAGx flag by writing a logic one to the bit
•
Software clears the FIEx bit by writing a logic zero to it
•
A reset occurs
Even with the filter enabled, there is a combinational path from the FAULTx inputs to the PWM pins. This
logic is also capable of holding a fault condition in the event of loss of clock to the PWM module.
Table 25-21. Fault mapping
PWM pin
Controlling register bits
PWMA
DISA[1:0]
PWMB
DISB[1:0]
PWMX
DISX[1:0]
DISA0
DISA1
Disable
FAULT0
FAULT1
PWMA
Wait/Halt Mode
WAITEN
Debug Mode
DBGEN
Stop Mode