AP_HAL_Linux: Add Support for RCInput_UDP

very simple protocol to receive RC cmds via UDP
Add support for it on the bebop

libraries/AP_HAL_Linux/AP_HAL_Linux_Namespace.h

@@ -26,6 +26,7 @@ namespace Linux {
     class LinuxRCInput_AioPRU;
     class LinuxRCInput_Navio;
     class LinuxRCInput_ZYNQ;
+    class LinuxRCInput_UDP;
     class LinuxRCOutput_PRU;
     class LinuxRCOutput_AioPRU;
     class LinuxRCOutput_PCA9685;

libraries/AP_HAL_Linux/AP_HAL_Linux_Private.h

@@ -17,6 +17,7 @@
 #include "RCInput.h"
 #include "RCInput_AioPRU.h"
 #include "RCInput_Navio.h"
+#include "RCInput_UDP.h"
 #include "RCOutput_PRU.h"
 #include "RCOutput_AioPRU.h"
 #include "RCOutput_PCA9685.h"

libraries/AP_HAL_Linux/HAL_Linux_Class.cpp

@@ -79,6 +79,8 @@ static LinuxRCInput_AioPRU rcinDriver;
 static LinuxRCInput_Navio rcinDriver;
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_ZYNQ
 static LinuxRCInput_ZYNQ rcinDriver;
+#elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_BEBOP
+static LinuxRCInput_UDP  rcinDriver;
 #else
 static LinuxRCInput rcinDriver;
 #endif

libraries/AP_HAL_Linux/RCInput.cpp

@@ -337,4 +337,19 @@ void LinuxRCInput::_process_rc_pulse(uint16_t width_s0, uint16_t width_s1)
     _process_dsm_pulse(width_s0, width_s1);
 }
 
+/*
+ * Update channel values directly
+ */
+void LinuxRCInput::_update_periods(uint16_t *periods, uint8_t len)
+{
+    if (len > LINUX_RC_INPUT_NUM_CHANNELS) {
+        len = LINUX_RC_INPUT_NUM_CHANNELS;
+    }
+    for (unsigned int i=0; i < len; i++) {
+        _pwm_values[i] = periods[i];
+    }
+    _num_channels = len;
+    new_rc_input = true;
+}
+
 #endif // CONFIG_HAL_BOARD

libraries/AP_HAL_Linux/RCInput.h

@@ -25,6 +25,7 @@ public:
 
  protected:
     void _process_rc_pulse(uint16_t width_s0, uint16_t width_s1);
+    void _update_periods(uint16_t *periods, uint8_t len);
 
  private:
     volatile bool new_rc_input;

libraries/AP_HAL_Linux/RCInput_UDP.cpp

@@ -0,0 +1,54 @@
+#include <AP_HAL/AP_HAL.h>
+
+#if CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_BEBOP
+#include "RCInput_UDP.h"
+#include <stdio.h>
+
+extern const AP_HAL::HAL& hal;
+
+using namespace Linux;
+
+LinuxRCInput_UDP::LinuxRCInput_UDP() :
+    _port(0),
+    _last_buf_ts(0),
+    _last_buf_seq(0)
+{}
+
+void LinuxRCInput_UDP::init(void *)
+{
+    _port = RCINPUT_UDP_DEF_PORT;
+    if(!_socket.bind("0.0.0.0", _port)) {
+        hal.console->printf("failed to bind UDP socket\n");
+    }
+
+    _socket.set_blocking(false);
+
+    return;
+}
+
+void LinuxRCInput_UDP::_timer_tick(void)
+{
+    uint64_t delay;
+    uint16_t seq_inc;
+
+    /* Read from udp */
+    while (_socket.recv(&_buf, sizeof(_buf), 10) == sizeof(_buf)) {
+        if (_buf.version != RCINPUT_UDP_VERSION) {
+            hal.console->printf("bad protocol version for UDP RCInput\n");
+            return;
+        }
+        if (_last_buf_ts != 0 &&
+            (delay = _buf.timestamp_us - _last_buf_ts) > 100000) {
+            hal.console->printf("no rc cmds received for %llu\n", delay);
+        }
+        _last_buf_ts = _buf.timestamp_us;
+
+        if ((seq_inc = _buf.sequence - _last_buf_seq) > 10) {
+            hal.console->printf("gap in rc cmds : %u\n", seq_inc);
+        }
+        _last_buf_seq = _buf.sequence;
+
+        _update_periods(_buf.pwms, RCINPUT_UDP_NUM_CHANNELS);
+    }
+}
+#endif

libraries/AP_HAL_Linux/RCInput_UDP.h

@@ -0,0 +1,24 @@
+
+#ifndef _AP_HAL_LINUX_RCINPUT_UDP_H
+#define _AP_HAL_LINUX_RCINPUT_UDP_H
+
+#include "RCInput.h"
+#include <AP_HAL/utility/Socket.h>
+#include "RCInput_UDP_Protocol.h"
+
+#define RCINPUT_UDP_DEF_PORT 777
+
+class Linux::LinuxRCInput_UDP : public Linux::LinuxRCInput
+{
+public:
+    LinuxRCInput_UDP();
+    void init(void*);
+    void _timer_tick(void);
+private:
+    SocketAPM   _socket{true};
+    uint16_t     _port;
+    struct rc_udp_packet _buf;
+    uint64_t _last_buf_ts;
+    uint16_t _last_buf_seq;
+};
+#endif // _AP_HAL_LINUX_RCINPUT_UDP_H

libraries/AP_HAL_Linux/RCInput_UDP_Protocol.h

@@ -0,0 +1,14 @@
+#ifndef _RCINPUT_UDP_PROTOCOL_H
+#define _RCINPUT_UDP_PROTOCOL_H
+
+#define RCINPUT_UDP_NUM_CHANNELS 8
+#define RCINPUT_UDP_VERSION 2
+
+struct __attribute__((packed)) rc_udp_packet {
+    uint32_t version;
+    uint64_t timestamp_us;
+    uint16_t sequence;
+    uint16_t pwms[RCINPUT_UDP_NUM_CHANNELS];
+};
+
+#endif