AP_BoardConfig: add support for PWM Voltage level setting

libraries/AP_BoardConfig/AP_BoardConfig.cpp

@@ -221,6 +221,15 @@ const AP_Param::GroupInfo AP_BoardConfig::var_info[] = {
     AP_GROUPINFO("SD_SLOWDOWN",  17,     AP_BoardConfig, _sdcard_slowdown,  0),
 #endif
 
+#ifdef HAL_GPIO_PWM_VOLT_PIN
+    // @Param: PWM_VOLT_SEL
+    // @DisplayName: Set PWM Out Voltage
+    // @Description: This sets the voltage max for PWM output pulses. 0 for 3.3V and 1 for 5V output.
+    //@Values: 0:3.3V,1:5V
+    // @User: Advanced
+    AP_GROUPINFO("PWM_VOLT_SEL", 18, AP_BoardConfig, _pwm_volt_sel, 0),
+#endif
+
     AP_GROUPEND
 };
 

libraries/AP_BoardConfig/AP_BoardConfig.h

@@ -216,6 +216,10 @@ private:
     AP_Float _vservo_min;
 #endif
 
+#ifdef HAL_GPIO_PWM_VOLT_PIN
+    AP_Int8 _pwm_volt_sel;
+#endif
+
 #if CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS
     AP_Int8 _sdcard_slowdown;
 #endif

libraries/AP_BoardConfig/board_drivers.cpp

@@ -345,6 +345,14 @@ void AP_BoardConfig::board_setup()
     hal.rcin->init();
     hal.rcout->init();
 #endif
+
+#if HAL_GPIO_PWM_VOLT_PIN
+    if (_pwm_volt_sel == 0) {
+        hal.gpio->write(HAL_GPIO_PWM_VOLT_PIN, 1); //set pin for 3.3V PWM Output
+    } else if (_pwm_volt_sel == 1) {
+        hal.gpio->write(HAL_GPIO_PWM_VOLT_PIN, 0); //set pin for 5V PWM Output
+    }
+#endif
     board_setup_uart();
     board_setup_sbus();
 #if AP_FEATURE_BOARD_DETECT