Prevent hard-fault when no IO available for transponder.

This cleans up the transponder api too.

src/main/drivers/transponder_ir.c

@@ -39,7 +39,7 @@ uint8_t transponderIrDMABuffer[TRANSPONDER_DMA_BUFFER_SIZE];
 
 volatile uint8_t transponderIrDataTransferInProgress = 0;
 
-void transponderIrInit(void)
+bool transponderIrInit(void)
 {
     memset(&transponderIrDMABuffer, 0, TRANSPONDER_DMA_BUFFER_SIZE);
 
@@ -51,7 +51,13 @@ void transponderIrInit(void)
         }
     }
 
+    if (!ioTag) {
+        return false;
+    }
+
+
     transponderIrHardwareInit(ioTag);
+    return true;
 }
 
 bool isTransponderIrReady(void)

src/main/drivers/transponder_ir.h

@@ -30,7 +30,7 @@
 #define BIT_TOGGLE_1 78 // (156 / 2)
 #define BIT_TOGGLE_0 0
 
-void transponderIrInit();
+bool transponderIrInit();
 void transponderIrDisable(void);
 
 void transponderIrHardwareInit(ioTag_t ioTag);

src/main/drivers/transponder_ir_stm32f30x.c

@@ -45,10 +45,6 @@ static void TRANSPONDER_DMA_IRQHandler(dmaChannelDescriptor_t* descriptor)
 
 void transponderIrHardwareInit(ioTag_t ioTag)
 {
-    if (!ioTag) {
-        return;
-    }
-
     TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
     TIM_OCInitTypeDef  TIM_OCInitStructure;
     DMA_InitTypeDef DMA_InitStructure;

src/main/fc/fc_init.c

@@ -490,7 +490,6 @@ void init(void)
 #ifdef TRANSPONDER
     if (feature(FEATURE_TRANSPONDER)) {
         transponderInit(masterConfig.transponderData);
-        transponderEnable();
         transponderStartRepeating();
         systemState |= SYSTEM_STATE_TRANSPONDER_ENABLED;
     }

src/main/io/transponder_ir.c

@@ -75,21 +75,14 @@ void transponderUpdate(timeUs_t currentTimeUs)
 
 void transponderInit(uint8_t* transponderData)
 {
-    transponderInitialised = false;
-    transponderIrInit();
+    transponderInitialised = transponderIrInit();
+    if (!transponderInitialised) {
+        return;
+    }
+
     transponderIrUpdateData(transponderData);
 }
 
-void transponderEnable(void)
-{
-    transponderInitialised = true;
-}
-
-void transponderDisable(void)
-{
-    transponderInitialised = false;
-}
-
 void transponderStopRepeating(void)
 {
     transponderRepeat = false;
@@ -97,11 +90,19 @@ void transponderStopRepeating(void)
 
 void transponderStartRepeating(void)
 {
+    if (!transponderInitialised) {
+        return;
+    }
+
     transponderRepeat = true;
 }
 
 void transponderUpdateData(uint8_t* transponderData)
 {
+    if (!transponderInitialised) {
+        return;
+    }
+
     transponderIrUpdateData(transponderData);
 }
 

src/main/io/transponder_ir.h

@@ -21,8 +21,6 @@
 
 void transponderInit(uint8_t* transponderCode);
 
-void transponderEnable(void);
-void transponderDisable(void);
 void transponderUpdate(timeUs_t currentTimeUs);
 void transponderUpdateData(uint8_t* transponderData);
 void transponderTransmitOnce(void);