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stspin32g4: Add bootstrap capacitor charge mode on enable to avoid high side UVLO error on enable #72

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stspin32g4: Add bootstrap capacitor charge mode on enable to avoid high side UVLO error on enable #72

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37 changes: 36 additions & 1 deletion src/drivers/stspin32g4/STSPIN32G4.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -37,10 +37,45 @@ int STSPIN32G4::init(){

// TODO init fault monitor

bootstrap_charge();

return isReady() ? 1 : 0;
};


void STSPIN32G4::enable()
{
bootstrap_charge();
BLDCDriver6PWM::enable();
}


void STSPIN32G4::bootstrap_charge()
{
//store phase states, enable low side drive
static const int num_phases = sizeof(phase_state)/sizeof(phase_state[0]);
PhaseState phase_state_before[num_phases];
bool none_disabled = true;
for (size_t i = 0; i < num_phases; i++)
{
phase_state_before[i] = phase_state[i];
if (phase_state[i] == PHASE_HI || phase_state[i] == PHASE_OFF)
{
none_disabled = false;
}
}
if (none_disabled)
{
return;
}
setPhaseState(PHASE_LO, PHASE_LO, PHASE_LO);
setPwm(0,0,0);
_delay(bootstrap_capacitor_charge_time);
//restore phase states
for (size_t i = 0; i < num_phases; i++)
{
phase_state[i] = phase_state_before[i];
}
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@runger1101001 runger1101001 Jan 29, 2026

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I'm wondering if we should add another setPwm here to actually apply the restored phase state.

But I'm also wondering about the purpose of remembering and restoring at all?

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@Moddingear Moddingear Jan 29, 2026 •
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Yeah, a SetPWM should probably be called, I figured it wouldn't hurt to leave it in the charge state...

As for remembering and restoring, the logic was that this code would leave the driver in the same state as it found it, and would skip charging if it was already activated...

}

void STSPIN32G4::wake() {
digitalWrite(STSPIN32G4_PIN_WAKE, HIGH);
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5 changes: 5 additions & 0 deletions src/drivers/stspin32g4/STSPIN32G4.h
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Expand Up @@ -116,8 +116,13 @@ class STSPIN32G4 : public BLDCDriver6PWM {
STSPIN32G4();
~STSPIN32G4();

unsigned int bootstrap_capacitor_charge_time = 10; //time to let the bootstrap capacitors charge for, in ms. During his time, brakes are applied. This is not necessary if the motor is rotating, as the BEMF allows the caps to charge.

int init() override;

void enable() override;

void bootstrap_charge();
void wake();
void sleep();
bool isReady();
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