Merge pull request #485 from paparazzi/sbus

Sbus radio control driver

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 +1,20 @@
+#
+# Makefile for shared radio_control SBUS subsystem
+#
+
+$(TARGET).CFLAGS	+= -DRADIO_CONTROL
+ifneq ($(RADIO_CONTROL_LED),none)
+	ap.CFLAGS += -DRADIO_CONTROL_LED=$(RADIO_CONTROL_LED)
+endif
+
+# convert SBUS_PORT to upper and lower case strings:
+SBUS_PORT_UPPER=$(shell echo $(SBUS_PORT) | tr a-z A-Z)
+SBUS_PORT_LOWER=$(shell echo $(SBUS_PORT) | tr A-Z a-z)
+
+$(TARGET).CFLAGS += -DUSE_$(SBUS_PORT_UPPER) -D$(SBUS_PORT_UPPER)_BAUD=B100000
+$(TARGET).CFLAGS += -DSBUS_UART_DEV=$(SBUS_PORT_LOWER)
+$(TARGET).CFLAGS += -DRADIO_CONTROL_TYPE_H=\"subsystems/radio_control/sbus.h\"
+$(TARGET).CFLAGS += -DRADIO_CONTROL_TYPE_SBUS
+$(TARGET).srcs	+= $(SRC_SUBSYSTEMS)/radio_control.c
+$(TARGET).srcs	+= $(SRC_SUBSYSTEMS)/radio_control/sbus.c
+

conf/radios/T10CG_SBUS.xml

@@ -0,0 +1,55 @@
+<?xml version="1.0"?>
+<!-- $Id$
+--
+-- (c) 2013 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.
+-->
+
+<!--
+-- Attributes of root (Radio) tag :
+-- name: name of RC
+-- data_min: min width of a pulse to be considered as a data pulse
+-- data_max: max width of a pulse to be considered as a data pulse
+-- sync_min: min width of a pulse to be considered as a synchro pulse
+-- sync_max: max width of a pulse to be considered as a synchro pulse
+-- pulse_type: POSITIVE ( Futaba and others) | NEGATIVE (JR)
+-- min, max and sync are expressed in micro-seconds
+-->
+
+<!--
+-- Attributes of channel tag :
+-- ctl: name of the command on the transmitter - only for displaying
+-- function: logical command
+-- average: (boolean) channel filtered through several frames (for discrete commands)
+-- min: minimum pulse length (micro-seconds)
+-- max: maximum pulse length (micro-seconds)
+-- neutral: neutral pulse length (micro-seconds)
+-- Note: a command may be reversed by exchanging min and max values
+-->
+
+<!DOCTYPE radio SYSTEM "radio.dtd">
+<radio name="Futaba T10CG with SBUS" data_min="900" data_max="2100" sync_min ="5000" sync_max ="15000" pulse_type="POSITIVE">
+ <channel ctl="A" function="ROLL"     min="363" neutral="1024" max="1683" average="0"/>
+ <channel ctl="B" function="PITCH"    min="363" neutral="1024" max="1683" average="0"/>
+ <channel ctl="C" function="THROTTLE" min="1683" neutral="1683" max="363" average="0"/>
+ <channel ctl="D" function="YAW"      min="363" neutral="1024" max="1683" average="0"/>
+ <channel ctl="E" function="MODE"     max="137" neutral="1024" min="1908" average="1"/>
+ <channel ctl="F" function="GAIN1"    min="137" neutral="1024" max="1908" average="0"/>
+ <channel ctl="G" function="GAIN2"    min="137" neutral="1024" max="1908" average="0"/>
+</radio>

sw/airborne/arch/lpc21/mcu_periph/uart_arch.c

@@ -68,6 +68,10 @@ void uart_periph_set_baudrate(struct uart_periph* p, uint32_t baud) {
   uart_enable_interrupts(p);
 }
 
+void uart_periph_set_bits_stop_parity(struct uart_periph* p, uint8_t __attribute__((unused)) bits, uint8_t __attribute__((unused)) stop, uint8_t __attribute__((unused)) parity) {
+  // TBD
+}
+
 void uart_transmit(struct uart_periph* p, uint8_t data ) {
   uint16_t temp;
   unsigned cpsr;

sw/airborne/arch/stm32/mcu_periph/uart_arch.c

@@ -41,11 +41,8 @@
 
 void uart_periph_set_baudrate(struct uart_periph* p, uint32_t baud) {
 
-  /* Configure USART */
+  /* Configure USART baudrate */
   usart_set_baudrate((uint32_t)p->reg_addr, baud);
-  usart_set_databits((uint32_t)p->reg_addr, 8);
-  usart_set_stopbits((uint32_t)p->reg_addr, USART_STOPBITS_1);
-  usart_set_parity((uint32_t)p->reg_addr, USART_PARITY_NONE);
 
   /* Disable Idle Line interrupt */
   USART_CR1((uint32_t)p->reg_addr) &= ~USART_CR1_IDLEIE;
@@ -61,6 +58,33 @@ void uart_periph_set_baudrate(struct uart_periph* p, uint32_t baud) {
 
 }
 
+void uart_periph_set_bits_stop_parity(struct uart_periph* p, uint8_t bits, uint8_t stop, uint8_t parity) {
+  /* Configure USART parity and data bits */
+  if (parity == UPARITY_EVEN) {
+    usart_set_parity((uint32_t)p->reg_addr, USART_PARITY_EVEN);
+    if (bits == UBITS_7)
+      usart_set_databits((uint32_t)p->reg_addr, 8);
+    else // 8 data bits by default
+      usart_set_databits((uint32_t)p->reg_addr, 9);
+  }
+  else if (parity == USART_PARITY_ODD) {
+    usart_set_parity((uint32_t)p->reg_addr, USART_PARITY_ODD);
+    if (bits == UBITS_7)
+      usart_set_databits((uint32_t)p->reg_addr, 8);
+    else // 8 data bits by default
+      usart_set_databits((uint32_t)p->reg_addr, 9);
+  }
+  else { // 8 data bist, NO_PARITY by default
+    usart_set_parity((uint32_t)p->reg_addr, USART_PARITY_NONE);
+    usart_set_databits((uint32_t)p->reg_addr, 8); // is 7bits without parity possible ?
+  }
+  /* Configure USART stop bits */
+  if (stop == USTOP_2)
+    usart_set_stopbits((uint32_t)p->reg_addr, USART_STOPBITS_2);
+  else // 1 stop bit by default
+    usart_set_stopbits((uint32_t)p->reg_addr, USART_STOPBITS_1);
+}
+
 void uart_periph_set_mode(struct uart_periph* p, bool_t tx_enabled, bool_t rx_enabled, bool_t hw_flow_control) {
   uint32_t mode = 0;
   if (tx_enabled)
@@ -173,6 +197,18 @@ static inline void usart_enable_irq(uint8_t IRQn) {
 #define UART1_HW_FLOW_CONTROL FALSE
 #endif
 
+#ifndef UART1_BITS
+#define UART1_BITS UBITS_8
+#endif
+
+#ifndef UART1_STOP
+#define UART1_STOP USTOP_1
+#endif
+
+#ifndef UART1_PARITY
+#define UART1_PARITY UPARITY_NO
+#endif
+
 void uart1_init( void ) {
 
   uart_periph_init(&uart1);
@@ -201,7 +237,8 @@ void uart1_init( void ) {
   /* Configure USART1, enable hardware flow control*/
   uart_periph_set_mode(&uart1, USE_UART1_TX, USE_UART1_RX, UART1_HW_FLOW_CONTROL);
 
-  /* Set USART1 baudrate and enable interrupt */
+  /* Set USART1 parameters and enable interrupt */
+  uart_periph_set_bits_stop_parity(&uart1, UART1_BITS, UART1_STOP, UART1_PARITY);
   uart_periph_set_baudrate(&uart1, UART1_BAUD);
 }
 
@@ -224,6 +261,18 @@ void usart1_isr(void) { usart_isr(&uart1); }
 #define UART2_HW_FLOW_CONTROL FALSE
 #endif
 
+#ifndef UART2_BITS
+#define UART2_BITS UBITS_8
+#endif
+
+#ifndef UART2_STOP
+#define UART2_STOP USTOP_1
+#endif
+
+#ifndef UART2_PARITY
+#define UART2_PARITY UPARITY_NO
+#endif
+
 void uart2_init( void ) {
 
   uart_periph_init(&uart2);
@@ -253,6 +302,7 @@ void uart2_init( void ) {
   uart_periph_set_mode(&uart2, USE_UART2_TX, USE_UART2_RX, UART2_HW_FLOW_CONTROL);
 
   /* Configure USART */
+  uart_periph_set_bits_stop_parity(&uart2, UART2_BITS, UART2_STOP, UART2_PARITY);
   uart_periph_set_baudrate(&uart2, UART2_BAUD);
 }
 
@@ -275,6 +325,18 @@ void usart2_isr(void) { usart_isr(&uart2); }
 #define UART3_HW_FLOW_CONTROL FALSE
 #endif
 
+#ifndef UART3_BITS
+#define UART3_BITS UBITS_8
+#endif
+
+#ifndef UART3_STOP
+#define UART3_STOP USTOP_1
+#endif
+
+#ifndef UART3_PARITY
+#define UART3_PARITY UPARITY_NO
+#endif
+
 void uart3_init( void ) {
 
   uart_periph_init(&uart3);
@@ -304,6 +366,7 @@ void uart3_init( void ) {
   uart_periph_set_mode(&uart3, USE_UART3_TX, USE_UART3_RX, UART3_HW_FLOW_CONTROL);
 
   /* Configure USART */
+  uart_periph_set_bits_stop_parity(&uart3, UART3_BITS, UART3_STOP, UART3_PARITY);
   uart_periph_set_baudrate(&uart3, UART3_BAUD);
 }
 
@@ -322,6 +385,18 @@ void usart3_isr(void) { usart_isr(&uart3); }
 #define USE_UART4_RX TRUE
 #endif
 
+#ifndef UART4_BITS
+#define UART4_BITS UBITS_8
+#endif
+
+#ifndef UART4_STOP
+#define UART4_STOP USTOP_1
+#endif
+
+#ifndef UART4_PARITY
+#define UART4_PARITY UPARITY_NO
+#endif
+
 void uart4_init( void ) {
 
   uart_periph_init(&uart4);
@@ -342,6 +417,7 @@ void uart4_init( void ) {
 
   /* Configure USART */
   uart_periph_set_mode(&uart4, USE_UART4_TX, USE_UART4_RX, FALSE);
+  uart_periph_set_bits_stop_parity(&uart4, UART4_BITS, UART4_STOP, UART4_PARITY);
   uart_periph_set_baudrate(&uart4, UART4_BAUD);
 }
 
@@ -360,6 +436,18 @@ void uart4_isr(void) { usart_isr(&uart4); }
 #define USE_UART5_RX TRUE
 #endif
 
+#ifndef UART5_BITS
+#define UART5_BITS UBITS_8
+#endif
+
+#ifndef UART5_STOP
+#define UART5_STOP USTOP_1
+#endif
+
+#ifndef UART5_PARITY
+#define UART5_PARITY UPARITY_NO
+#endif
+
 void uart5_init( void ) {
 
   uart_periph_init(&uart5);
@@ -380,6 +468,7 @@ void uart5_init( void ) {
 
   /* Configure USART */
   uart_periph_set_mode(&uart5, USE_UART5_TX, USE_UART5_RX, FALSE);
+  uart_periph_set_bits_stop_parity(&uart5, UART5_BITS, UART5_STOP, UART5_PARITY);
   uart_periph_set_baudrate(&uart5, UART5_BAUD);
 }
 
@@ -402,6 +491,18 @@ void uart5_isr(void) { usart_isr(&uart5); }
 #define UART6_HW_FLOW_CONTROL FALSE
 #endif
 
+#ifndef UART6_BITS
+#define UART6_BITS UBITS_8
+#endif
+
+#ifndef UART6_STOP
+#define UART6_STOP USTOP_1
+#endif
+
+#ifndef UART6_PARITY
+#define UART6_PARITY UPARITY_NO
+#endif
+
 void uart6_init( void ) {
 
   uart_periph_init(&uart6);
@@ -430,7 +531,7 @@ void uart6_init( void ) {
 
   /* Configure USART Tx,Rx and hardware flow control*/
   uart_periph_set_mode(&uart6, USE_UART6_TX, USE_UART6_RX, UART6_HW_FLOW_CONTROL);
-
+  uart_periph_set_bits_stop_parity(&uart6, UART6_BITS, UART6_STOP, UART6_PARITY);
   uart_periph_set_baudrate(&uart6, UART6_BAUD);
 }
 

sw/airborne/boards/apogee_1.0.h

@@ -112,18 +112,11 @@
 
 #define POWER_SWITCH_LED 9
 
-/* Uart2 RX polarity, on PB13, 1 on LED_ON, 0 on LED_OFF */
-#ifndef USE_LED_10
-#define USE_LED_10 1
-#endif
-#define LED_10_GPIO GPIOB
-#define LED_10_GPIO_CLK RCC_AHB1ENR_IOPBEN
-#define LED_10_GPIO_PIN GPIO13
-#define LED_10_GPIO_ON gpio_set
-#define LED_10_GPIO_OFF gpio_clear
-#define LED_10_AFIO_REMAP ((void)0)
 
-#define RC_POLARITY_LED 10
+/* Pint to set Uart2 RX polarity, on PB13, output high inverts, low doesn't */
+#define RC_POLARITY_GPIO_PORT GPIOB
+#define RC_POLARITY_GPIO_PIN GPIO13
+
 
 /* Default actuators driver */
 #define DEFAULT_ACTUATORS "subsystems/actuators/actuators_pwm.h"

sw/airborne/firmwares/fixedwing/fbw_downlink.h

@@ -66,6 +66,14 @@
                     PPM_NB_CHANNEL,                          \
                     ppm_pulses_usec);                        \
 }
+#elif defined RADIO_CONTROL_TYPE_SBUS
+#include "subsystems/radio_control/sbus.h"
+#define PERIODIC_SEND_PPM(_trans, _dev) {                           \
+  DOWNLINK_SEND_PPM(_trans, _dev,                            \
+                    &radio_control.frame_rate,               \
+                    SBUS_NB_CHANNEL,                          \
+                    sbus.pulses);                        \
+}
 #else
 #define PERIODIC_SEND_PPM(_trans, _dev) {}
 #endif

sw/airborne/led.h

@@ -74,6 +74,16 @@ static inline void led_init ( void ) {
   LED_OFF(8);
 #endif /* LED_8 */
 
+#if USE_LED_9
+  LED_INIT(9);
+  LED_OFF(9);
+#endif /* LED_9 */
+
+#if USE_LED_10
+  LED_INIT(10);
+  LED_OFF(10);
+#endif /* LED_10 */
+
 #ifdef USE_LED_BODY
   LED_INIT(BODY);
   LED_OFF(BODY);

sw/airborne/mcu_periph/uart.h

@@ -46,10 +46,21 @@
 #define B19200   19200
 #define B38400   38400
 #define B57600   57600
+#define B100000  100000
 #define B115200  115200
 #define B230400  230400
 #define B921600  921600
 
+#define UBITS_7 7
+#define UBITS_8 8
+
+#define USTOP_1 1
+#define USTOP_2 2
+
+#define UPARITY_NO    0
+#define UPARITY_ODD   1
+#define UPARITY_EVEN  2
+
 /**
  * UART peripheral
  */
@@ -75,6 +86,7 @@ struct uart_periph {
 
 extern void uart_periph_init(struct uart_periph* p);
 extern void uart_periph_set_baudrate(struct uart_periph* p, uint32_t baud);
+extern void uart_periph_set_bits_stop_parity(struct uart_periph* p, uint8_t bits, uint8_t stop, uint8_t parity);
 extern void uart_periph_set_mode(struct uart_periph* p, bool_t tx_enabled, bool_t rx_enabled, bool_t hw_flow_control);
 extern void uart_transmit(struct uart_periph* p, uint8_t data);
 extern bool_t uart_check_free_space(struct uart_periph* p, uint8_t len);
@@ -97,6 +109,7 @@ extern void uart0_init(void);
 #define UART0Getch() uart_getch(&uart0)
 #define UART0TxRunning uart0.tx_running
 #define UART0SetBaudrate(_b) uart_periph_set_baudrate(&uart0, _b)
+#define UART0SetBitsStopParity(_b, _s, _p) uart_periph_set_bits_stop_parity(&uart0, _b, _s, _p)
 
 #endif // USE_UART0
 
@@ -112,6 +125,7 @@ extern void uart1_init(void);
 #define UART1Getch() uart_getch(&uart1)
 #define UART1TxRunning uart1.tx_running
 #define UART1SetBaudrate(_b) uart_periph_set_baudrate(&uart1, _b)
+#define UART1SetBitsStopParity(_b, _s, _p) uart_periph_set_bits_stop_parity(&uart1, _b, _s, _p)
 
 #endif // USE_UART1
 
@@ -127,6 +141,7 @@ extern void uart2_init(void);
 #define UART2Getch() uart_getch(&uart2)
 #define UART2TxRunning uart2.tx_running
 #define UART2SetBaudrate(_b) uart_periph_set_baudrate(&uart2, _b)
+#define UART2SetBitsStopParity(_b, _s, _p) uart_periph_set_bits_stop_parity(&uart2, _b, _s, _p)
 
 #endif // USE_UART2
 
@@ -142,6 +157,7 @@ extern void uart3_init(void);
 #define UART3Getch() uart_getch(&uart3)
 #define UART3TxRunning uart3.tx_running
 #define UART3SetBaudrate(_b) uart_periph_set_baudrate(&uart3, _b)
+#define UART3SetBitsStopParity(_b, _s, _p) uart_periph_set_bits_stop_parity(&uart3, _b, _s, _p)
 
 #endif // USE_UART3
 
@@ -157,6 +173,7 @@ extern void uart4_init(void);
 #define UART4Getch() uart_getch(&uart4)
 #define UART4TxRunning uart4.tx_running
 #define UART4SetBaudrate(_b) uart_periph_set_baudrate(&uart4, _b)
+#define UART4SetBitsStopParity(_b, _s, _p) uart_periph_set_bits_stop_parity(&uart4, _b, _s, _p)
 
 #endif // USE_UART4
 
@@ -172,6 +189,7 @@ extern void uart5_init(void);
 #define UART5Getch() uart_getch(&uart5)
 #define UART5TxRunning uart5.tx_running
 #define UART5SetBaudrate(_b) uart_periph_set_baudrate(&uart5, _b)
+#define UART5SetBitsStopParity(_b, _s, _p) uart_periph_set_bits_stop_parity(&uart5, _b, _s, _p)
 
 #endif // USE_UART5
 
@@ -187,6 +205,7 @@ extern void uart6_init(void);
 #define UART6Getch() uart_getch(&uart6)
 #define UART6TxRunning uart6.tx_running
 #define UART6SetBaudrate(_b) uart_periph_set_baudrate(&uart6, _b)
+#define UART6SetBitsStopParity(_b, _s, _p) uart_periph_set_bits_stop_parity(&uart6, _b, _s, _p)
 
 #endif // USE_UART6
 

sw/airborne/subsystems/radio_control/sbus.c

@@ -0,0 +1,145 @@
+/*
+ * 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 "mcu_periph/gpio.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_FLAGS_BYTE 22
+#define SBUS_FRAME_LOST_BIT 2
+
+#define SBUS_STATUS_UNINIT      0
+#define SBUS_STATUS_GOT_START   1
+
+/** Set polarity using RC_POLARITY_GPIO.
+ * SBUS signal has a reversed polarity compared to normal UART
+ * this allows to using hardware UART peripheral by changing
+ * the input signal polarity.
+ * Setting this gpio ouput high inverts the signal,
+ * output low sets it to normal polarity.
+ */
+#ifndef RC_SET_POLARITY
+#define RC_SET_POLARITY gpio_output_high
+#endif
+
+
+/** 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)
+  uart_periph_set_bits_stop_parity(&SBUS_UART_DEV, UBITS_8, USTOP_2, UPARITY_EVEN);
+  uart_periph_set_baudrate(&SBUS_UART_DEV, B100000);
+
+  // Set polarity
+#ifdef RC_POLARITY_GPIO_PORT
+  gpio_setup_output(RC_POLARITY_GPIO_PORT, RC_POLARITY_GPIO_PIN);
+  RC_SET_POLARITY(RC_POLARITY_GPIO_PORT, RC_POLARITY_GPIO_PIN);
+#endif
+}
+
+
+/** Decode the raw buffer */
+static void decode_sbus_buffer (const uint8_t *src, uint16_t *dst, bool_t *available)
+{
+  // 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++;
+    }
+  }
+  // test frame lost flag
+  *available = !bit_is_set(src[SBUS_FLAGS_BYTE], SBUS_FRAME_LOST_BIT);
+}
+
+// Decoding event function
+// Reading from UART
+void sbus_decode_event(void) {
+  uint8_t rbyte;
+  if (uart_char_available(&SBUS_UART_DEV)) {
+    do {
+      rbyte = uart_getch(&SBUS_UART_DEV);
+      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.frame_available);
+            }
+            sbus.status = SBUS_STATUS_UNINIT;
+          }
+          break;
+        default:
+          break;
+      }
+    } while (uart_char_available(&SBUS_UART_DEV));
+  }
+}
+

sw/airborne/subsystems/radio_control/sbus.h

@@ -0,0 +1,95 @@
+/*
+ * 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"
+
+/**
+ * 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.
+ *
+ * SBUS frame always have 16 channels
+ * but only the X first one will be available
+ * depending of the RC transmitter.
+ * The radio XML file is used to assign the
+ * input values to RC 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 */