Recoverable Fault

The PWM provides a Recoverable Fault mode on fault 1 and 2 (see figure Fault Protection).

The recoverable fault signal is an internal signal generated as soon as an external trigger event occurs (see PWM External Trigger Mode).

When the fault 1 or 2 is defined as a recoverable fault, the corresponding fault input pin is ignored and bits FFIL1/2, FMOD1/2 and FFIL1/2 are not taken into account.

The fault 1 is managed as a recoverable fault by the PWMEXTRG1 input trigger when PWM_ETRG1.RFEN = 1, PWM_ENA.CHID1 = 1, and PWM_ETRG1.TRGMODE ≠ 0.

The fault 2 is managed as a recoverable fault by the PWMEXTRG2 input trigger when PWM_ETRG2.RFEN = 1, PWM_ENA.CHID2 = 1, and PWM_ETRG2.TRGMODE ≠ 0.

Recoverable fault 1 and 2 can be taken into account by all channels by enabling the bit FPEx[1/2] in the PWM Fault Protection Enable registers (PWM_FPEx). However the synchronous channels (see Synchronous Channels) do not use their own fault enable bits, but those of the channel 0 (bits FPE0[1/2]).

When a recoverable fault is triggered (according to the PWM_ETRGx.TRGMODE setting), the PWM counter of the affected channels is not cleared (unlike in the classic fault protection mechanism) but the channel outputs are forced to the values defined by the fields FPVHx and FPVLx in the PWM Fault Protection Value Register 1 (PWM_FPV), as per table Forcing Values of PWM Outputs by Fault Protection. The output forcing is made asynchronously to the channel counter and lasts from the recoverable fault occurrence to the end of the next PWM cycle (if the recoverable fault is no longer present) (see the figure below).

The recoverable fault does not trigger an interrupt. The Fault Status FSy (with y = 1 or 2) is not reported in the PWM Fault Status Register when the fault y is a recoverable fault.

See Cycle-By-Cycle Duty Mode: LED String Control for an application case associating the Recoverable Fault mode with the External Trigger mode.