OP-1477 - Add ubx handling libraries

flight/libraries/inc/ubx_utils.h

@@ -0,0 +1,62 @@
+/**
+ ******************************************************************************
+ *
+ * @file       ubx_utils.h
+ * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2014.
+ * @brief      UBX Protocol utilities
+ *             --
+ * @see        The GNU Public License (GPL) Version 3
+ *
+ *****************************************************************************/
+/*
+ * This program 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+#ifndef UBX_UTILS_H_
+#define UBX_UTILS_H_
+
+#include <stdint.h>
+#include <stdbool.h>
+
+typedef struct {
+    uint8_t  syn1;
+    uint8_t  syn2;
+    uint8_t  class;
+    uint8_t  id;
+    uint16_t len;
+} __attribute__((packed)) UBXHeader_t;
+
+typedef struct {
+    uint8_t chk1;
+    uint8_t chk2;
+} __attribute__((packed)) UBXFooter_t;
+
+typedef union {
+    uint8_t bynarystream[0];
+    struct {
+        UBXHeader_t header;
+        uint8_t     payload[0];
+    } packet;
+} UBXPacket_t;
+
+#define UBX_HEADER_LEN (sizeof(UBXHeader_t))
+
+#define UBX_SYN1       0xB5
+#define UBX_SYN2       0x62
+
+bool ubx_getLastSentence(uint8_t *data, uint16_t bufferCount, uint8_t * *lastSentence, uint16_t *lenght);
+void ubx_appendChecksum(UBXPacket_t *pkt);
+void ubx_buildPacket(UBXPacket_t *pkt, uint8_t packetClass, uint8_t packetId, uint16_t len);
+
+#endif /* UBX_UTILS_H_ */

flight/libraries/ubx_utils.c

@@ -0,0 +1,77 @@
+/**
+ ******************************************************************************
+ *
+ * @file       ubx_utils.c
+ * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2014.
+ * @brief      UBX Protocol utilities.
+ *             --
+ * @see        The GNU Public License (GPL) Version 3
+ *
+ *****************************************************************************/
+/*
+ * This program 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+#include <ubx_utils.h>
+bool ubx_getLastSentence(uint8_t *data, uint16_t bufferCount, uint8_t * *lastSentence, uint16_t *lenght)
+{
+    const uint8_t packet_overhead = UBX_HEADER_LEN + 2;
+    uint8_t *current = data + bufferCount - packet_overhead;
+
+    while (current >= data) {
+        // look for a ubx a sentence
+        if (current[0] == UBX_SYN1 && current[1] == UBX_SYN2) {
+            // check whether it fits the current buffer (whole sentence is into buffer)
+            uint16_t len = current[4] + (current[5] << 8);
+            if (len + packet_overhead + current <= data + bufferCount) {
+                *lastSentence = current;
+                *lenght = len + packet_overhead;
+                return true;
+            }
+        }
+        current--;
+    }
+    // no complete sentence found
+    return false;
+}
+
+void ubx_buildPacket(UBXPacket_t *pkt, uint8_t packetClass, uint8_t packetId, uint16_t len)
+{
+    pkt->packet.header.syn1 = UBX_SYN1;
+    pkt->packet.header.syn2 = UBX_SYN2;
+
+    // don't make any assumption on alignments...
+    ((uint8_t *)&pkt->packet.header.len)[0] = len & 0xFF;
+    ((uint8_t *)&pkt->packet.header.len)[1] = (len >> 8) & 0xFF;
+
+    pkt->packet.header.class = packetClass;
+    pkt->packet.header.id    = packetId;
+    ubx_appendChecksum(pkt);
+}
+
+void ubx_appendChecksum(UBXPacket_t *pkt)
+{
+    uint8_t chkA = 0;
+    uint8_t chkB = 0;
+    uint16_t len = ((uint8_t *)&pkt->packet.header.len)[0] | ((uint8_t *)&pkt->packet.header.len)[1] << 8;
+
+    // From class field to the end of payload
+    for (uint8_t i = 2; i < len + UBX_HEADER_LEN; i++) {
+        chkA += pkt->bynarystream[i];
+        chkB += chkA;
+    }
+    ;
+    pkt->packet.payload[len]     = chkA;
+    pkt->packet.payload[len + 1] = chkB;
+}

flight/targets/boards/gpsplatinum/firmware/Makefile

@@ -50,6 +50,7 @@ SRC += $(CMSIS_DEVICEDIR)/system_stm32f0xx.c
 ## Application Core
 SRC += $(OPSYSTEM)/gpsp.c
 SRC += $(OPSYSTEM)/pios_board.c
+SRC += $(FLIGHTLIB)/ubx_utils.c
 #SRC += $(FLIGHTLIB)/alarms.c
 #SRC += $(OPUAVOBJ)/uavobjectmanager.c
 #SRC += $(OPUAVOBJ)/eventdispatcher.c