SPRacingF3Mini - Reduce current draw when using transponder while

connected via USB cable.

Makefile

@@ -741,6 +741,7 @@ SPRACINGF3MINI_SRC	 = \
 		   drivers/sdcard_standard.c \
 		   drivers/transponder_ir.c \
 		   drivers/transponder_ir_stm32f30x.c \
+		   drivers/usb_detection.c \
 		   io/asyncfatfs/asyncfatfs.c \
 		   io/asyncfatfs/fat_standard.c \
 		   io/transponder_ir.c \

src/main/drivers/usb_detection.c

@@ -0,0 +1,63 @@
+/*
+ * This file is part of Cleanflight.
+ *
+ * Cleanflight is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Cleanflight is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "sdcard.h"
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "platform.h"
+
+#include "gpio.h"
+
+#include "drivers/system.h"
+
+void usbCableDetectDeinit(void)
+{
+#ifdef USB_DETECT_PIN
+    GPIO_InitTypeDef  GPIO_InitStructure;
+
+    GPIO_InitStructure.GPIO_Pin = USB_DETECT_PIN;
+    GPIO_Init(USB_DETECT_GPIO_PORT, &GPIO_InitStructure);
+#endif
+}
+
+void usbCableDetectInit(void)
+{
+#ifdef USB_DETECT_PIN
+    RCC_AHBPeriphClockCmd(USB_DETECT_GPIO_CLK, ENABLE);
+
+    GPIO_InitTypeDef  GPIO_InitStructure;
+
+    GPIO_InitStructure.GPIO_Pin = USB_DETECT_PIN;
+    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
+    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
+    GPIO_Init(USB_DETECT_GPIO_PORT, &GPIO_InitStructure);
+#endif
+}
+
+bool usbCableIsInserted(void)
+{
+    bool result = false;
+
+#ifdef USB_DETECT_PIN
+    result = (GPIO_ReadInputData(USB_DETECT_GPIO_PORT) & USB_DETECT_PIN) != 0;
+#endif
+
+    return result;
+}

src/main/drivers/usb_detection.h

@@ -0,0 +1,22 @@
+/*
+ * This file is part of Cleanflight.
+ *
+ * Cleanflight is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Cleanflight is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+void usbCableDetectDeinit(void);
+void usbCableDetectInit(void);
+bool usbCableIsInserted(void);

src/main/io/transponder_ir.c

@@ -28,6 +28,8 @@
 #include "drivers/transponder_ir.h"
 #include "drivers/system.h"
 
+#include "drivers/usb_detection.h"
+
 #include "io/transponder_ir.h"
 #include "config/config.h"
 
@@ -63,6 +65,13 @@ void updateTransponder(void)
 
     nextUpdateAt = now + 4500 + jitter;
 
+#ifdef SPRACINGF3MINI
+    // reduce current draw when USB cable is plugged in by decreasing the transponder transmit rate.
+    if (usbCableIsInserted()) {
+        nextUpdateAt = now + (1000 * 1000) / 10; // 10 hz.
+    }
+#endif
+
     transponderIrTransmit();
 }
 

src/main/main.c

@@ -128,6 +128,7 @@ void spektrumBind(rxConfig_t *rxConfig);
 const sonarHardware_t *sonarGetHardwareConfiguration(batteryConfig_t *batteryConfig);
 void sonarInit(const sonarHardware_t *sonarHardware);
 void transponderInit(uint8_t* transponderCode);
+void usbCableDetectInit(void);
 
 #ifdef STM32F303xC
 // from system_stm32f30x.c
@@ -522,6 +523,10 @@ void init(void)
     }
 #endif
 
+#ifdef USB_CABLE_DETECTION
+    usbCableDetectInit();
+#endif
+
 #ifdef TRANSPONDER
     transponderInit(masterConfig.transponderData);
     transponderEnable();

src/main/target/SPRACINGF3MINI/target.h

@@ -194,6 +194,11 @@
 #define TRANSPONDER_DMA_CHANNEL              DMA1_Channel2
 #define TRANSPONDER_IRQ                      DMA1_Channel2_IRQn
 
+#define USB_CABLE_DETECTION
+#define USB_DETECT_PIN                   GPIO_Pin_5
+#define USB_DETECT_GPIO_PORT             GPIOB
+#define USB_DETECT_GPIO_CLK              RCC_AHBPeriph_GPIOC
+
 #define GPS
 #define BLACKBOX
 #define ENABLE_BLACKBOX_LOGGING_ON_SDCARD_BY_DEFAULT