AP_HAL: added sumd decoder

with thanks to the PX4 project
9 years ago · 9a7af89b30
2 changed files with 452 additions and 0 deletions
--- a/libraries/AP_HAL/utility/sumd.cpp
+++ b/libraries/AP_HAL/utility/sumd.cpp
@ -0,0 +1,392 @@
				@@ -0,0 +1,392 @@
+// -*- tab-width: 8; Mode: C++; c-basic-offset: 8; indent-tabs-mode: -*- t -*-
+/*
+  SUMD decoder, based on PX4Firmware/src/rc/lib/rc/sumd.c from PX4Firmware
+  modified for use in AP_HAL_* by Andrew Tridgell
+ */
+/****************************************************************************
+ *
+ *   Copyright (c) 2015 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/*
+ * @file sumd.h
+ *
+ * RC protocol definition for Graupner HoTT transmitter (SUMD/SUMH Protocol)
+ *
+ * @author Marco Bauer <marco@wtns.de>
+ */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdint.h>
+#include "sumd.h"
+
+#define SUMD_MAX_CHANNELS	32
+#define SUMD_HEADER_LENGTH	3
+#define SUMD_HEADER_ID		0xA8
+#define SUMD_ID_SUMH		0x00
+#define SUMD_ID_SUMD		0x01
+#define SUMD_ID_FAILSAFE	0x81
+
+
+#pragma pack(push, 1)
+typedef struct {
+	uint8_t	header;							///< 0xA8 for a valid packet
+	uint8_t	status;							///< 0x01 valid and live SUMD data frame / 0x00 = SUMH / 0x81 = Failsafe
+	uint8_t	length;							///< Channels
+	uint8_t	sumd_data[SUMD_MAX_CHANNELS * 2];	///< ChannelData (High Byte/ Low Byte)
+	uint8_t	crc16_high;						///< High Byte of 16 Bit CRC
+	uint8_t	crc16_low;						///< Low Byte of 16 Bit CRC
+	uint8_t	telemetry;						///< Telemetry request
+	uint8_t	crc8;							///< SUMH CRC8
+} ReceiverFcPacketHoTT;
+#pragma pack(pop)
+
+
+enum SUMD_DECODE_STATE {
+	SUMD_DECODE_STATE_UNSYNCED = 0,
+	SUMD_DECODE_STATE_GOT_HEADER,
+	SUMD_DECODE_STATE_GOT_STATE,
+	SUMD_DECODE_STATE_GOT_LEN,
+	SUMD_DECODE_STATE_GOT_DATA,
+	SUMD_DECODE_STATE_GOT_CRC,
+	SUMD_DECODE_STATE_GOT_CRC16_BYTE_1,
+	SUMD_DECODE_STATE_GOT_CRC16_BYTE_2
+};
+
+/*
+const char *decode_states[] = {"UNSYNCED",
+			       "GOT_HEADER",
+			       "GOT_STATE",
+			       "GOT_LEN",
+			       "GOT_DATA",
+			       "GOT_CRC",
+			       "GOT_CRC16_BYTE_1",
+			       "GOT_CRC16_BYTE_2"
+			      };
+*/
+
+static uint8_t 	_crc8 	= 0x00;
+static uint16_t 	_crc16 = 0x0000;
+static bool 		_sumd	= true;
+static bool		_crcOK	= false;
+static bool		_debug	= false;
+
+
+/* define range mapping here, -+100% -> 1000..2000 */
+#define SUMD_RANGE_MIN 0.0f
+#define SUMD_RANGE_MAX 4096.0f
+
+#define SUMD_TARGET_MIN 1000.0f
+#define SUMD_TARGET_MAX 2000.0f
+
+/* pre-calculate the floating point stuff as far as possible at compile time */
+#define SUMD_SCALE_FACTOR ((SUMD_TARGET_MAX - SUMD_TARGET_MIN) / (SUMD_RANGE_MAX - SUMD_RANGE_MIN))
+#define SUMD_SCALE_OFFSET (int)(SUMD_TARGET_MIN - (SUMD_SCALE_FACTOR * SUMD_RANGE_MIN + 0.5f))
+
+static enum SUMD_DECODE_STATE _decode_state = SUMD_DECODE_STATE_UNSYNCED;
+static uint8_t _rxlen;
+
+static ReceiverFcPacketHoTT _rxpacket;
+
+
+static uint16_t sumd_crc16(uint16_t crc, uint8_t value)
+{
+	int i;
+	crc ^= (uint16_t)value << 8;
+
+	for (i = 0; i < 8; i++) {
+		crc = (crc & 0x8000) ? (crc << 1) ^ 0x1021 : (crc << 1);
+	}
+
+	return crc;
+}
+
+static uint8_t sumd_crc8(uint8_t crc, uint8_t value)
+{
+	crc += value;
+	return crc;
+}
+
+int sumd_decode(uint8_t byte, uint8_t *rssi, uint8_t *rx_count, uint16_t *channel_count, uint16_t *channels,
+		uint16_t max_chan_count)
+{
+
+	int ret = 1;
+
+	switch (_decode_state) {
+	case SUMD_DECODE_STATE_UNSYNCED:
+		if (_debug) {
+			printf(" SUMD_DECODE_STATE_UNSYNCED \n") ;
+		}
+
+		if (byte == SUMD_HEADER_ID) {
+			_rxpacket.header = byte;
+			_sumd = true;
+			_rxlen = 0;
+			_crc16 = 0x0000;
+			_crc8 = 0x00;
+			_crcOK = false;
+			_crc16 = sumd_crc16(_crc16, byte);
+			_crc8 = sumd_crc8(_crc8, byte);
+			_decode_state = SUMD_DECODE_STATE_GOT_HEADER;
+
+			if (_debug) {
+				printf(" SUMD_DECODE_STATE_GOT_HEADER: %x \n", byte) ;
+			}
+
+		} else {
+			ret = 3;
+		}
+
+		break;
+
+	case SUMD_DECODE_STATE_GOT_HEADER:
+		if (byte == SUMD_ID_SUMD || byte == SUMD_ID_SUMH) {
+			_rxpacket.status = byte;
+
+			if (byte == SUMD_ID_SUMH) {
+				_sumd = false;
+			}
+
+			if (_sumd) {
+				_crc16 = sumd_crc16(_crc16, byte);
+
+			} else {
+				_crc8 = sumd_crc8(_crc8, byte);
+			}
+
+			_decode_state = SUMD_DECODE_STATE_GOT_STATE;
+
+			if (_debug) {
+				printf(" SUMD_DECODE_STATE_GOT_STATE: %x \n", byte) ;
+			}
+
+		} else {
+			_decode_state = SUMD_DECODE_STATE_UNSYNCED;
+		}
+
+		break;
+
+	case SUMD_DECODE_STATE_GOT_STATE:
+		if (byte >= 2 && byte <= SUMD_MAX_CHANNELS) {
+			_rxpacket.length = byte;
+
+			if (_sumd) {
+				_crc16 = sumd_crc16(_crc16, byte);
+
+			} else {
+				_crc8 = sumd_crc8(_crc8, byte);
+			}
+
+			_rxlen++;
+			_decode_state = SUMD_DECODE_STATE_GOT_LEN;
+
+			if (_debug) {
+				printf(" SUMD_DECODE_STATE_GOT_LEN: %x (%d) \n", byte, byte) ;
+			}
+
+		} else {
+			_decode_state = SUMD_DECODE_STATE_UNSYNCED;
+		}
+
+		break;
+
+	case SUMD_DECODE_STATE_GOT_LEN:
+		_rxpacket.sumd_data[_rxlen] = byte;
+
+		if (_sumd) {
+			_crc16 = sumd_crc16(_crc16, byte);
+
+		} else {
+			_crc8 = sumd_crc8(_crc8, byte);
+		}
+
+		_rxlen++;
+
+		if (_rxlen <= ((_rxpacket.length * 2))) {
+			if (_debug) {
+				printf(" SUMD_DECODE_STATE_GOT_DATA[%d]: %x\n", _rxlen - 2, byte) ;
+			}
+
+		} else {
+			_decode_state = SUMD_DECODE_STATE_GOT_DATA;
+
+			if (_debug) {
+				printf(" SUMD_DECODE_STATE_GOT_DATA -- finish --\n") ;
+			}
+
+		}
+
+		break;
+
+	case SUMD_DECODE_STATE_GOT_DATA:
+		_rxpacket.crc16_high = byte;
+
+		if (_debug) {
+			printf(" SUMD_DECODE_STATE_GOT_CRC16[1]: %x   [%x]\n", byte, ((_crc16 >> 8) & 0xff)) ;
+		}
+
+		if (_sumd) {
+			_decode_state = SUMD_DECODE_STATE_GOT_CRC;
+
+		} else {
+			_decode_state = SUMD_DECODE_STATE_GOT_CRC16_BYTE_1;
+		}
+
+		break;
+
+	case SUMD_DECODE_STATE_GOT_CRC16_BYTE_1:
+		_rxpacket.crc16_low = byte;
+
+		if (_debug) {
+			printf(" SUMD_DECODE_STATE_GOT_CRC16[2]: %x   [%x]\n", byte, (_crc16 & 0xff)) ;
+		}
+
+		_decode_state = SUMD_DECODE_STATE_GOT_CRC16_BYTE_2;
+
+		break;
+
+	case SUMD_DECODE_STATE_GOT_CRC16_BYTE_2:
+		_rxpacket.telemetry = byte;
+
+		if (_debug) {
+			printf(" SUMD_DECODE_STATE_GOT_SUMH_TELEMETRY: %x\n", byte) ;
+		}
+
+		_decode_state = SUMD_DECODE_STATE_GOT_CRC;
+
+		break;
+
+	case SUMD_DECODE_STATE_GOT_CRC:
+		if (_sumd) {
+			_rxpacket.crc16_low = byte;
+
+			if (_debug) {
+				printf(" SUMD_DECODE_STATE_GOT_CRC[2]: %x   [%x]\n\n", byte, (_crc16 & 0xff)) ;
+			}
+
+			if (_crc16 == (uint16_t)(_rxpacket.crc16_high << 8) + _rxpacket.crc16_low) {
+				_crcOK = true;
+			}
+
+		} else {
+			_rxpacket.crc8 = byte;
+
+			if (_debug) {
+				printf(" SUMD_DECODE_STATE_GOT_CRC8_SUMH: %x   [%x]\n\n", byte, _crc8) ;
+			}
+
+			if (_crc8 == _rxpacket.crc8) {
+				_crcOK = true;
+			}
+		}
+
+		if (_crcOK) {
+			if (_debug) {
+				printf(" CRC - OK \n") ;
+			}
+
+			if (_sumd) {
+				if (_debug) {
+					printf(" Got valid SUMD Packet\n") ;
+				}
+
+			} else {
+				if (_debug) {
+					printf(" Got valid SUMH Packet\n") ;
+				}
+
+			}
+
+			if (_debug) {
+				printf(" RXLEN: %d  [Chans: %d] \n\n", _rxlen - 1, (_rxlen - 1) / 2) ;
+			}
+
+			ret = 0;
+			unsigned i;
+			uint8_t _cnt = *rx_count + 1;
+			*rx_count = _cnt;
+
+			*rssi = 100;
+
+			/* received Channels */
+			if ((uint16_t)_rxpacket.length > max_chan_count) {
+				_rxpacket.length = (uint8_t) max_chan_count;
+			}
+
+			*channel_count = (uint16_t)_rxpacket.length;
+
+			/* decode the actual packet */
+			/* reorder first 4 channels */
+
+			/* ch1 = roll -> sumd = ch2 */
+			channels[0] = (uint16_t)((_rxpacket.sumd_data[1 * 2 + 1] << 8) | _rxpacket.sumd_data[1 * 2 + 2]) >> 3;
+			/* ch2 = pitch -> sumd = ch2 */
+			channels[1] = (uint16_t)((_rxpacket.sumd_data[2 * 2 + 1] << 8) | _rxpacket.sumd_data[2 * 2 + 2]) >> 3;
+			/* ch3 = throttle -> sumd = ch2 */
+			channels[2] = (uint16_t)((_rxpacket.sumd_data[0 * 2 + 1] << 8) | _rxpacket.sumd_data[0 * 2 + 2]) >> 3;
+			/* ch4 = yaw -> sumd = ch2 */
+			channels[3] = (uint16_t)((_rxpacket.sumd_data[3 * 2 + 1] << 8) | _rxpacket.sumd_data[3 * 2 + 2]) >> 3;
+
+			/* we start at channel 5(index 4) */
+			unsigned chan_index = 4;
+
+			for (i = 4; i < _rxpacket.length; i++) {
+				if (_debug) {
+					printf("ch[%d] : %x %x [ %x    %d ]\n", i + 1, _rxpacket.sumd_data[i * 2 + 1], _rxpacket.sumd_data[i * 2 + 2],
+					       ((_rxpacket.sumd_data[i * 2 + 1] << 8) | _rxpacket.sumd_data[i * 2 + 2]) >> 3,
+					       ((_rxpacket.sumd_data[i * 2 + 1] << 8) | _rxpacket.sumd_data[i * 2 + 2]) >> 3);
+				}
+
+				channels[chan_index] = (uint16_t)((_rxpacket.sumd_data[i * 2 + 1] << 8) | _rxpacket.sumd_data[i * 2 + 2]) >> 3;
+				/* convert values to 1000-2000 ppm encoding in a not too sloppy fashion */
+				//channels[chan_index] = (uint16_t)(channels[chan_index] * SUMD_SCALE_FACTOR + .5f) + SUMD_SCALE_OFFSET;
+
+				chan_index++;
+			}
+
+		} else {
+			/* decoding failed */
+			ret = 4;
+
+			if (_debug) {
+				printf(" CRC - fail \n") ;
+			}
+
+		}
+
+		_decode_state = SUMD_DECODE_STATE_UNSYNCED;
+		break;
+	}
+
+	return ret;
+}
--- a/libraries/AP_HAL/utility/sumd.h
+++ b/libraries/AP_HAL/utility/sumd.h
@ -0,0 +1,60 @@
				@@ -0,0 +1,60 @@
+// -*- tab-width: 8; Mode: C++; c-basic-offset: 8; indent-tabs-mode: -*- t -*-
+/*
+  SUMD decoder, based on PX4Firmware/src/rc/lib/rc/sumd.c from PX4Firmware
+  modified for use in AP_HAL_* by Andrew Tridgell
+ */
+/****************************************************************************
+ *
+ *   Copyright (c) 2015 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file sumd.h
+ *
+ * RC protocol definition for Graupner HoTT transmitter
+ *
+ * @author Marco Bauer <marco@wtns.de>
+ */
+
+#pragma once
+
+/**
+ * Decoder for SUMD/SUMH protocol
+ *
+ * @param byte current char to read
+ * @param rssi pointer to a byte where the RSSI value is written back to
+ * @param rx_count pointer to a byte where the receive count of packets signce last wireless frame is written back to
+ * @param channels pointer to a datastructure of size max_chan_count where channel values (12 bit) are written back to
+ * @param max_chan_count maximum channels to decode - if more channels are decoded, the last n are skipped and success (0) is returned
+ * @return 0 for success (a decoded packet), 1 for no packet yet (accumulating), 2 for unknown packet, 3 for out of sync, 4 for checksum error
+ */
+int sumd_decode(uint8_t byte, uint8_t *rssi, uint8_t *rx_count, uint16_t *channel_count,
+                uint16_t *channels, uint16_t max_chan_count);