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

src/drivers/stspin32g4/STSPIN32G4.cpp

@@ -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];
+    }
+}
 
 void STSPIN32G4::wake() {
     digitalWrite(STSPIN32G4_PIN_WAKE, HIGH);

src/drivers/stspin32g4/STSPIN32G4.h

@@ -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();