[radio] add initial support for Futaba SBUS protocol

conf/airframes/ENAC/fixed-wing/apogee.xml

@@ -23,10 +23,10 @@
     <define name="USE_GYRO_PITCH_RATE"/>
 
     <target name="sim" board="pc"/>
-    <target name="ap" board="apogee_0.99"/>
+    <target name="ap" board="apogee_1.0"/>
-    <configure name="FLASH_MODE" value="SWD"/>
+    <!--configure name="FLASH_MODE" value="SWD"/-->
 
-    <subsystem name="radio_control" type="ppm"/>
+    <subsystem name="radio_control" type="sbus"/>
 
     <!-- Communication -->
     <subsystem name="telemetry" type="transparent"/>

conf/firmwares/subsystems/shared/radio_control_sbus.makefile

@@ -0,0 +1,13 @@
+#
+# Makefile for shared radio_control SBUS subsystem
+#
+
+$(TARGET).CFLAGS	+= -DRADIO_CONTROL
+ifneq ($(RADIO_CONTROL_LED),none)
+	ap.CFLAGS += -DRADIO_CONTROL_LED=$(RADIO_CONTROL_LED)
+endif
+$(TARGET).CFLAGS += -DUSE_$(SBUS_PORT) -DSBUS_LINK=$(SBUS_PORT) -D$(SBUS_PORT)_BAUD=B100000
+$(TARGET).CFLAGS 	+= -DRADIO_CONTROL_TYPE_H=\"subsystems/radio_control/sbus.h\"
+$(TARGET).CFLAGS 	+= -DRADIO_CONTROL_TYPE_SBUS
+$(TARGET).srcs	+= $(SRC_SUBSYSTEMS)/radio_control.c
+$(TARGET).srcs	+= $(SRC_SUBSYSTEMS)/radio_control/sbus.c

sw/airborne/subsystems/radio_control/sbus.c

@@ -0,0 +1,144 @@
+/*
+ * Copyright (C) 2013 Alexandre Bustico, Gautier Hattenberger
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi 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 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi 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 paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/** @file subsystems/radio_control/sbus.c
+ *
+ * Futaba SBUS decoder
+ */
+
+#include "subsystems/radio_control.h"
+#include "subsystems/radio_control/sbus.h"
+#include BOARD_CONFIG
+#include "mcu_periph/uart.h"
+#include <string.h>
+
+/*
+ * SBUS protocol and state machine status
+ */
+#define SBUS_START_BYTE 0x0f
+#define SBUS_END_BYTE 0x00
+#define SBUS_BIT_PER_CHANNEL 11
+#define SBUS_BIT_PER_BYTE 8
+
+#define SBUS_STATUS_UNINIT      0
+#define SBUS_STATUS_GOT_START   1
+
+/** Set polarity using RC_POLARITY_LED.
+ *  SBUS signal has a reversed polarity compared to normal UART
+ *  this allow to using hardware UART peripheral by changing
+ * the input signal polarity
+ */
+#ifndef RC_SET_POLARITY
+#define RC_SET_POLARITY LED_ON
+#endif
+
+/** UART selecting
+ */
+#define __SBusLink(dev, _x) dev##_x
+#define _SBusLink(dev, _x)  __SBusLink(dev, _x)
+#define SBusLink(_x) _SBusLink(SBUS_LINK, _x)
+
+/* SBUS struct */
+struct _sbus sbus;
+
+// Init function
+void radio_control_impl_init(void) {
+  sbus.frame_available = FALSE;
+  sbus.status = SBUS_STATUS_UNINIT;
+
+  // Set UART parameters (100K, 8 bits, 2 stops, even parity)
+  SBusLink(SetBitsStopParity(UBITS_8, USTOP_2, UPARITY_EVEN));
+  SBusLink(SetBaudrate(B100000));
+
+  // Set polarity
+#ifdef RC_POLARITY_LED
+  RC_SET_POLARITY(RC_POLARITY_LED);
+#endif
+}
+
+/*
+ * This part is used by the autopilot to read data from a uart
+ */
+#define SBusBuffer() SBusLink(ChAvailable())
+#define SBusGet() SBusLink(Getch())
+
+// Decode the raw buffer
+static void decode_sbus_buffer (const uint8_t *src, uint16_t *dst)
+{
+  // reset counters
+  uint8_t byteInRawBuf = 0;
+  uint8_t bitInRawBuf = 0;
+  uint8_t channel = 0;
+  uint8_t bitInChannel = 0;
+
+  // clear bits
+  memset (dst, 0, SBUS_NB_CHANNEL*sizeof(uint16_t));
+
+  // decode sbus data
+  for (uint8_t i=0; i< (SBUS_NB_CHANNEL*SBUS_BIT_PER_CHANNEL); i++) {
+    if (src[byteInRawBuf] & (1<<bitInRawBuf))
+      dst[channel] |= (1<<bitInChannel);
+
+    bitInRawBuf++;
+    bitInChannel++;
+
+    if (bitInRawBuf == SBUS_BIT_PER_BYTE) {
+      bitInRawBuf = 0;
+      byteInRawBuf++;
+    }
+    if (bitInChannel == SBUS_BIT_PER_CHANNEL) {
+      bitInChannel = 0;
+      channel++;
+    }
+  }
+}
+
+// Decoding event function
+// Reading from UART
+void sbus_decode_event(void) {
+  uint8_t rbyte;
+  if (SBusBuffer()) {
+    do {
+      rbyte = SBusGet();
+      switch (sbus.status) {
+        case SBUS_STATUS_UNINIT:
+          // Wait for the start byte
+          if (rbyte == SBUS_START_BYTE) {
+            sbus.status++;
+            sbus.idx = 0;
+          }
+          break;
+        case SBUS_STATUS_GOT_START:
+          // Store buffer
+          sbus.buffer[sbus.idx] = rbyte;
+          sbus.idx++;
+          if (sbus.idx == SBUS_BUF_LENGTH) {
+            // Decode if last byte is the correct end byte
+            if (rbyte == SBUS_END_BYTE) decode_sbus_buffer(sbus.buffer, sbus.pulses);
+            sbus.status = SBUS_STATUS_UNINIT;
+          }
+          break;
+        default:
+          break;
+      }
+    } while (SBusBuffer());
+  }
+}

sw/airborne/subsystems/radio_control/sbus.h

@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2013 Alexandre Bustico, Gautier Hattenberger
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi 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 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi 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 paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef RC_SBUS_H
+#define RC_SBUS_H
+
+/** @file subsystems/radio_control/sbus.h
+ *
+ * Futaba SBUS decoder
+ */
+
+#include "std.h"
+
+///**
+// * Architecture dependant code
+// */
+//#include "subsystems/radio_control/ppm_arch.h"
+///* must be implemented by arch dependant code */
+//extern void ppm_arch_init(void);
+
+/**
+ * Dummy macro to use radio.h file
+ */
+#define RC_PPM_TICKS_OF_USEC(_v)        (_v)
+#define RC_PPM_SIGNED_TICKS_OF_USEC(_v) (_v)
+#define USEC_OF_RC_PPM_TICKS(_v)        (_v)
+
+/**
+ * Generated code holding the description of a given
+ * transmitter
+ */
+#include "generated/radio.h"
+
+/**
+ * Define number of channels
+ */
+#define SBUS_BUF_LENGTH 24
+#define SBUS_NB_CHANNEL 16
+#define RADIO_CONTROL_NB_CHANNEL SBUS_NB_CHANNEL
+
+/**
+ * SBUS structure
+ */
+struct _sbus {
+  uint16_t pulses[SBUS_NB_CHANNEL]; ///< decoded values
+  bool_t frame_available;           ///< new frame available
+  uint8_t buffer[SBUS_BUF_LENGTH];  ///< input buffer
+  uint8_t idx;                      ///< input index
+  uint8_t status;                   ///< decoder state machine status
+};
+
+extern struct _sbus sbus;
+
+/**
+ * Decoding event function
+ */
+extern void sbus_decode_event(void);
+
+/**
+ * Event macro with handler callback
+ */
+#define RadioControlEvent(_received_frame_handler) {  \
+  sbus_decode_event();                                \
+  if (sbus.frame_available) {                         \
+    radio_control.frame_cpt++;                        \
+    radio_control.time_since_last_frame = 0;          \
+    if (radio_control.radio_ok_cpt > 0) {             \
+      radio_control.radio_ok_cpt--;                   \
+    } else {                                          \
+      radio_control.status = RC_OK;                   \
+      NormalizePpmIIR(sbus.pulses,radio_control);     \
+      _received_frame_handler();                      \
+    }                                                 \
+    sbus.frame_available = FALSE;                     \
+  }                                                   \
+}
+
+#endif /* RC_SBUS_H */