AP_RCProtocol: support DSM bind

libraries/AP_RCProtocol/AP_RCProtocol.cpp

@@ -57,6 +57,13 @@ bool AP_RCProtocol::new_input()
 {
     bool ret = _new_input;
     _new_input = false;
+
+    // run update function on backends
+    for (uint8_t i = 0; i < AP_RCProtocol::NONE; i++) {
+        if (backend[i] != nullptr) {
+            backend[i]->update();
+        }
+    }
     return ret;
 }
 
@@ -75,3 +82,15 @@ uint16_t AP_RCProtocol::read(uint8_t chan)
     }
     return 0;
 }
+
+/*
+  ask for bind start on supported receivers (eg spektrum satellite)
+ */
+void AP_RCProtocol::start_bind(void)
+{
+    for (uint8_t i = 0; i < AP_RCProtocol::NONE; i++) {
+        if (backend[i] != nullptr) {
+            backend[i]->start_bind();
+        }
+    }
+}

libraries/AP_RCProtocol/AP_RCProtocol.h

@@ -36,6 +36,8 @@ public:
     uint8_t num_channels();
     uint16_t read(uint8_t chan);
     bool new_input();
+    void start_bind(void);
+    
 private:
     enum rcprotocol_t _detected_protocol = NONE;
     AP_RCProtocol_Backend *backend[NONE];

libraries/AP_RCProtocol/AP_RCProtocol_Backend.h

@@ -30,6 +30,12 @@ public:
     bool new_input();
     uint8_t num_channels();
 
+    // support for receivers that have FC initiated bind support
+    virtual void start_bind(void) {}
+
+    // allow for backends that need regular polling
+    virtual void update(void) {}
+
 protected:
     void add_input(uint8_t num_channels, uint16_t *values, bool in_failsafe);
     

libraries/AP_RCProtocol/AP_RCProtocol_DSM.cpp

@@ -19,10 +19,10 @@
  */
 #include "AP_RCProtocol_DSM.h"
 
-// #define DEBUG
-
-#ifdef DEBUG
 extern const AP_HAL::HAL& hal;
+
+// #define DEBUG
+#ifdef DEBUG
 # define debug(fmt, args...)	hal.console->printf(fmt "\n", ##args)
 #else
 # define debug(fmt, args...)	do {} while(0)
@@ -361,3 +361,71 @@ bool AP_RCProtocol_DSM::dsm_decode(uint64_t frame_time, const uint8_t dsm_frame[
 	 */
 	return true;
 }
+
+
+/*
+  start bind on DSM satellites
+ */
+void AP_RCProtocol_DSM::start_bind(void)
+{
+    bind_state = BIND_STATE1;
+}
+
+
+/*
+  update function used for bind state machine
+ */
+void AP_RCProtocol_DSM::update(void)
+{
+#if defined(HAL_GPIO_SPEKTRUM_PWR) && defined(HAL_GPIO_SPEKTRUM_RC)
+    switch (bind_state) {
+    case BIND_STATE_NONE:
+        break;
+
+    case BIND_STATE1:
+        hal.gpio->write(HAL_GPIO_SPEKTRUM_PWR, !HAL_SPEKTRUM_PWR_ENABLED);
+        hal.gpio->pinMode(HAL_GPIO_SPEKTRUM_RC, 1);
+        hal.gpio->write(HAL_GPIO_SPEKTRUM_RC, 1);
+        bind_last_ms = AP_HAL::millis();
+        bind_state = BIND_STATE2;
+        break;
+
+    case BIND_STATE2: {
+        uint32_t now = AP_HAL::millis();
+        if (now - bind_last_ms > 500) {
+            hal.gpio->write(HAL_GPIO_SPEKTRUM_PWR, HAL_SPEKTRUM_PWR_ENABLED);
+            bind_last_ms = now;
+            bind_state = BIND_STATE3;
+        }
+        break;
+    }
+
+    case BIND_STATE3: {
+        uint32_t now = AP_HAL::millis();
+        if (now - bind_last_ms > 72) {
+            // 9 pulses works with all satellite receivers, and supports the highest
+            // available protocol
+            const uint8_t num_pulses = 9;
+            for (uint8_t i=0; i<num_pulses; i++) {
+                hal.scheduler->delay_microseconds(120);
+                hal.gpio->write(HAL_GPIO_SPEKTRUM_RC, 0);
+                hal.scheduler->delay_microseconds(120);
+                hal.gpio->write(HAL_GPIO_SPEKTRUM_RC, 1);                
+            }
+            bind_last_ms = now;
+            bind_state = BIND_STATE4;
+        }
+        break;
+    }
+        
+    case BIND_STATE4: {
+        uint32_t now = AP_HAL::millis();
+        if (now - bind_last_ms > 50) {
+            hal.gpio->pinMode(HAL_GPIO_SPEKTRUM_RC, 0);
+            bind_state = BIND_STATE_NONE;
+        }
+        break;
+    }
+    }
+#endif
+}

libraries/AP_RCProtocol/AP_RCProtocol_DSM.h

@@ -23,6 +23,9 @@ class AP_RCProtocol_DSM : public AP_RCProtocol_Backend {
 public:
     AP_RCProtocol_DSM(AP_RCProtocol &_frontend) : AP_RCProtocol_Backend(_frontend) {}
     void process_pulse(uint32_t width_s0, uint32_t width_s1) override;
+    void start_bind(void) override;
+    void update(void) override;
+    
 private:
     void dsm_decode();
     bool dsm_decode_channel(uint16_t raw, unsigned shift, unsigned *channel, unsigned *value);
@@ -37,4 +40,15 @@ private:
         uint16_t bytes[16]; // including start bit and stop bit
         uint16_t bit_ofs;
     } dsm_state;
-};
+
+    // bind state machine
+    enum {
+        BIND_STATE_NONE,
+        BIND_STATE1,
+        BIND_STATE2,
+        BIND_STATE3,
+        BIND_STATE4,
+    } bind_state;
+    uint32_t bind_last_ms;
+    
+};