/**
******************************************************************************
* @addtogroup OpenPilotSystem OpenPilot System
* @{
* @addtogroup OpenPilotLibraries OpenPilot System Libraries
* @{
*
* @file uavtalk.c
* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
* @brief UAVTalk library, implements to telemetry protocol. See the wiki for more details.
* This library should not be called directly by the application, it is only used by the
* Telemetry module.
* @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 "openpilot.h"
// Private constants
#define SYNC_VAL 0x3C
#define TYPE_MASK 0xF8
#define TYPE_VER 0x20
#define TYPE_OBJ (TYPE_VER | 0x00)
#define TYPE_OBJ_REQ (TYPE_VER | 0x01)
#define TYPE_OBJ_ACK (TYPE_VER | 0x02)
#define TYPE_ACK (TYPE_VER | 0x03)
#define TYPE_NACK (TYPE_VER | 0x04)
#define MIN_HEADER_LENGTH 8 // sync(1), type (1), size (2), object ID (4)
#define MAX_HEADER_LENGTH 10 // sync(1), type (1), size (2), object ID (4), instance ID (2, not used in single objects)
#define CHECKSUM_LENGTH 1
#define MAX_PAYLOAD_LENGTH 256
#define MAX_PACKET_LENGTH (MAX_HEADER_LENGTH + MAX_PAYLOAD_LENGTH + CHECKSUM_LENGTH)
// CRC lookup table
static const uint8_t crc_table[256] = {
0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15, 0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d,
0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65, 0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d,
0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5, 0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85, 0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd,
0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2, 0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea,
0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2, 0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32, 0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a,
0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42, 0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a,
0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c, 0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec, 0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4,
0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c, 0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44,
0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c, 0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b, 0x76, 0x71, 0x78, 0x7f, 0x6a, 0x6d, 0x64, 0x63,
0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b, 0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13,
0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb, 0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83,
0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb, 0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3
};
// Private types
typedef enum {STATE_SYNC, STATE_TYPE, STATE_SIZE, STATE_OBJID, STATE_INSTID, STATE_DATA, STATE_CS} RxState;
// Private variables
static UAVTalkOutputStream outStream;
static xSemaphoreHandle lock;
static xSemaphoreHandle transLock;
static xSemaphoreHandle respSema;
static UAVObjHandle respObj;
static uint16_t respInstId;
static uint8_t rxBuffer[MAX_PACKET_LENGTH];
static uint8_t txBuffer[MAX_PACKET_LENGTH];
static UAVTalkStats stats;
// Private functions
static uint8_t updateCRCbyte(uint8_t crc, const uint8_t data);
static uint8_t updateCRC(uint8_t crc, const uint8_t* data, int32_t length);
static int32_t objectTransaction(UAVObjHandle objectId, uint16_t instId, uint8_t type, int32_t timeout);
static int32_t sendObject(UAVObjHandle obj, uint16_t instId, uint8_t type);
static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type);
static int32_t sendNack(uint32_t objId);
static int32_t receiveObject(uint8_t type, uint32_t objId, uint16_t instId, uint8_t* data, int32_t length);
static void updateAck(UAVObjHandle obj, uint16_t instId);
/**
* Initialize the UAVTalk library
* \param[in] outputStream Function pointer that is called to send a data buffer
* \return 0 Success
* \return -1 Failure
*/
int32_t UAVTalkInitialize(UAVTalkOutputStream outputStream)
{
outStream = outputStream;
lock = xSemaphoreCreateRecursiveMutex();
transLock = xSemaphoreCreateRecursiveMutex();
vSemaphoreCreateBinary(respSema);
xSemaphoreTake(respSema, 0); // reset to zero
UAVTalkResetStats();
return 0;
}
/**
* Get communication statistics counters
* @param[out] statsOut Statistics counters
*/
void UAVTalkGetStats(UAVTalkStats* statsOut)
{
// Lock
xSemaphoreTakeRecursive(lock, portMAX_DELAY);
// Copy stats
memcpy(statsOut, &stats, sizeof(UAVTalkStats));
// Release lock
xSemaphoreGiveRecursive(lock);
}
/**
* Reset the statistics counters.
*/
void UAVTalkResetStats()
{
// Lock
xSemaphoreTakeRecursive(lock, portMAX_DELAY);
// Clear stats
memset(&stats, 0, sizeof(UAVTalkStats));
// Release lock
xSemaphoreGiveRecursive(lock);
}
/**
* Request an update for the specified object, on success the object data would have been
* updated by the GCS.
* \param[in] obj Object to update
* \param[in] instId The instance ID or UAVOBJ_ALL_INSTANCES for all instances.
* \param[in] timeout Time to wait for the response, when zero it will return immediately
* \return 0 Success
* \return -1 Failure
*/
int32_t UAVTalkSendObjectRequest(UAVObjHandle obj, uint16_t instId, int32_t timeout)
{
return objectTransaction(obj, instId, TYPE_OBJ_REQ, timeout);
}
/**
* Send the specified object through the telemetry link.
* \param[in] obj Object to send
* \param[in] instId The instance ID or UAVOBJ_ALL_INSTANCES for all instances.
* \param[in] acked Selects if an ack is required (1:ack required, 0: ack not required)
* \param[in] timeoutMs Time to wait for the ack, when zero it will return immediately
* \return 0 Success
* \return -1 Failure
*/
int32_t UAVTalkSendObject(UAVObjHandle obj, uint16_t instId, uint8_t acked, int32_t timeoutMs)
{
// Send object
if (acked == 1)
{
return objectTransaction(obj, instId, TYPE_OBJ_ACK, timeoutMs);
}
else
{
return objectTransaction(obj, instId, TYPE_OBJ, timeoutMs);
}
}
/**
* Execute the requested transaction on an object.
* \param[in] obj Object
* \param[in] instId The instance ID of UAVOBJ_ALL_INSTANCES for all instances.
* \param[in] type Transaction type
* TYPE_OBJ: send object,
* TYPE_OBJ_REQ: request object update
* TYPE_OBJ_ACK: send object with an ack
* \return 0 Success
* \return -1 Failure
*/
static int32_t objectTransaction(UAVObjHandle obj, uint16_t instId, uint8_t type, int32_t timeoutMs)
{
int32_t respReceived;
// Send object depending on if a response is needed
if (type == TYPE_OBJ_ACK || type == TYPE_OBJ_REQ)
{
// Get transaction lock (will block if a transaction is pending)
xSemaphoreTakeRecursive(transLock, portMAX_DELAY);
// Send object
xSemaphoreTakeRecursive(lock, portMAX_DELAY);
respObj = obj;
respInstId = instId;
sendObject(obj, instId, type);
xSemaphoreGiveRecursive(lock);
// Wait for response (or timeout)
respReceived = xSemaphoreTake(respSema, timeoutMs/portTICK_RATE_MS);
// Check if a response was received
if (respReceived == pdFALSE)
{
// Cancel transaction
xSemaphoreTakeRecursive(lock, portMAX_DELAY);
xSemaphoreTake(respSema, 0); // non blocking call to make sure the value is reset to zero (binary sema)
respObj = 0;
xSemaphoreGiveRecursive(lock);
xSemaphoreGiveRecursive(transLock);
return -1;
}
else
{
xSemaphoreGiveRecursive(transLock);
return 0;
}
}
else if (type == TYPE_OBJ)
{
xSemaphoreTakeRecursive(lock, portMAX_DELAY);
sendObject(obj, instId, TYPE_OBJ);
xSemaphoreGiveRecursive(lock);
return 0;
}
else
{
return -1;
}
}
/**
* Process an byte from the telemetry stream.
* \param[in] rxbyte Received byte
* \return 0 Success
* \return -1 Failure
*/
int32_t UAVTalkProcessInputStream(uint8_t rxbyte)
{
static UAVObjHandle obj;
static uint8_t type;
static uint16_t packet_size;
static uint32_t objId;
static uint16_t instId;
static uint32_t length;
static uint8_t cs, csRx;
static int32_t rxCount;
static RxState state = STATE_SYNC;
static uint16_t rxPacketLength = 0;
++stats.rxBytes;
if (rxPacketLength < 0xffff)
rxPacketLength++; // update packet byte count
// Receive state machine
switch (state)
{
case STATE_SYNC:
if (rxbyte != SYNC_VAL)
break;
// Initialize and update the CRC
cs = updateCRCbyte(0, rxbyte);
rxPacketLength = 1;
state = STATE_TYPE;
break;
case STATE_TYPE:
// update the CRC
cs = updateCRCbyte(cs, rxbyte);
if ((rxbyte & TYPE_MASK) != TYPE_VER)
{
state = STATE_SYNC;
break;
}
type = rxbyte;
packet_size = 0;
state = STATE_SIZE;
rxCount = 0;
break;
case STATE_SIZE:
// update the CRC
cs = updateCRCbyte(cs, rxbyte);
if (rxCount == 0)
{
packet_size += rxbyte;
rxCount++;
break;
}
packet_size += rxbyte << 8;
if (packet_size < MIN_HEADER_LENGTH || packet_size > MAX_HEADER_LENGTH + MAX_PAYLOAD_LENGTH)
{ // incorrect packet size
state = STATE_SYNC;
break;
}
rxCount = 0;
objId = 0;
state = STATE_OBJID;
break;
case STATE_OBJID:
// update the CRC
cs = updateCRCbyte(cs, rxbyte);
objId += rxbyte << (8*(rxCount++));
if (rxCount < 4)
break;
// Search for object, if not found reset state machine
// except if we got a OBJ_REQ for an object which does not
// exist, in which case we'll send a NACK
obj = UAVObjGetByID(objId);
if (obj == 0 && type != TYPE_OBJ_REQ)
{
stats.rxErrors++;
state = STATE_SYNC;
break;
}
// Determine data length
if (type == TYPE_OBJ_REQ || type == TYPE_ACK || type == TYPE_NACK)
length = 0;
else
length = UAVObjGetNumBytes(obj);
// Check length and determine next state
if (length >= MAX_PAYLOAD_LENGTH)
{
stats.rxErrors++;
state = STATE_SYNC;
break;
}
// Check the lengths match
if ((rxPacketLength + length) != packet_size)
{ // packet error - mismatched packet size
stats.rxErrors++;
state = STATE_SYNC;
break;
}
instId = 0;
if (obj == 0)
{
// If this is a NACK, we skip to Checksum
state = STATE_CS;
rxCount = 0;
}
// Check if this is a single instance object (i.e. if the instance ID field is coming next)
else if (UAVObjIsSingleInstance(obj))
{
// If there is a payload get it, otherwise receive checksum
if (length > 0)
state = STATE_DATA;
else
state = STATE_CS;
rxCount = 0;
}
else
{
state = STATE_INSTID;
rxCount = 0;
}
break;
case STATE_INSTID:
// update the CRC
cs = updateCRCbyte(cs, rxbyte);
instId += rxbyte << (8*(rxCount++));
if (rxCount < 2)
break;
rxCount = 0;
// If there is a payload get it, otherwise receive checksum
if (length > 0)
state = STATE_DATA;
else
state = STATE_CS;
break;
case STATE_DATA:
// update the CRC
cs = updateCRCbyte(cs, rxbyte);
rxBuffer[rxCount++] = rxbyte;
if (rxCount < length)
break;
state = STATE_CS;
rxCount = 0;
break;
case STATE_CS:
// the CRC byte
csRx = rxbyte;
if (csRx != cs)
{ // packet error - faulty CRC
stats.rxErrors++;
state = STATE_SYNC;
break;
}
if (rxPacketLength != (packet_size + 1))
{ // packet error - mismatched packet size
stats.rxErrors++;
state = STATE_SYNC;
break;
}
xSemaphoreTakeRecursive(lock, portMAX_DELAY);
receiveObject(type, objId, instId, rxBuffer, length);
stats.rxObjectBytes += length;
stats.rxObjects++;
xSemaphoreGiveRecursive(lock);
state = STATE_SYNC;
break;
default:
stats.rxErrors++;
state = STATE_SYNC;
}
// Done
return 0;
}
/**
* Receive an object. This function process objects received through the telemetry stream.
* \param[in] type Type of received message (TYPE_OBJ, TYPE_OBJ_REQ, TYPE_OBJ_ACK, TYPE_ACK, TYPE_NACK)
* \param[in] objId ID of the object to work on
* \param[in] instId The instance ID of UAVOBJ_ALL_INSTANCES for all instances.
* \param[in] data Data buffer
* \param[in] length Buffer length
* \return 0 Success
* \return -1 Failure
*/
static int32_t receiveObject(uint8_t type, uint32_t objId, uint16_t instId, uint8_t* data, int32_t length)
{
static UAVObjHandle obj;
int32_t ret = 0;
// Get the handle to the Object. Will be zero
// if object does not exist.
obj = UAVObjGetByID(objId);
// Process message type
switch (type) {
case TYPE_OBJ:
// All instances, not allowed for OBJ messages
if (instId != UAVOBJ_ALL_INSTANCES)
{
// Unpack object, if the instance does not exist it will be created!
UAVObjUnpack(obj, instId, data);
// Check if an ack is pending
updateAck(obj, instId);
}
else
{
ret = -1;
}
break;
case TYPE_OBJ_ACK:
// All instances, not allowed for OBJ_ACK messages
if (instId != UAVOBJ_ALL_INSTANCES)
{
// Unpack object, if the instance does not exist it will be created!
if ( UAVObjUnpack(obj, instId, data) == 0 )
{
// Transmit ACK
sendObject(obj, instId, TYPE_ACK);
}
else
{
ret = -1;
}
}
else
{
ret = -1;
}
break;
case TYPE_OBJ_REQ:
// Send requested object if message is of type OBJ_REQ
if (obj == 0)
sendNack(objId);
else
sendObject(obj, instId, TYPE_OBJ);
break;
case TYPE_NACK:
// Do nothing on flight side, let it time out.
break;
case TYPE_ACK:
// All instances, not allowed for ACK messages
if (instId != UAVOBJ_ALL_INSTANCES)
{
// Check if an ack is pending
updateAck(obj, instId);
}
else
{
ret = -1;
}
break;
default:
ret = -1;
}
// Done
return ret;
}
/**
* Check if an ack is pending on an object and give response semaphore
*/
static void updateAck(UAVObjHandle obj, uint16_t instId)
{
if (respObj == obj && (respInstId == instId || respInstId == UAVOBJ_ALL_INSTANCES))
{
xSemaphoreGive(respSema);
respObj = 0;
}
}
/**
* Send an object through the telemetry link.
* \param[in] obj Object handle to send
* \param[in] instId The instance ID or UAVOBJ_ALL_INSTANCES for all instances
* \param[in] type Transaction type
* \return 0 Success
* \return -1 Failure
*/
static int32_t sendObject(UAVObjHandle obj, uint16_t instId, uint8_t type)
{
uint32_t numInst;
uint32_t n;
// If all instances are requested and this is a single instance object, force instance ID to zero
if ( instId == UAVOBJ_ALL_INSTANCES && UAVObjIsSingleInstance(obj) )
{
instId = 0;
}
// Process message type
if ( type == TYPE_OBJ || type == TYPE_OBJ_ACK )
{
if (instId == UAVOBJ_ALL_INSTANCES)
{
// Get number of instances
numInst = UAVObjGetNumInstances(obj);
// Send all instances
for (n = 0; n < numInst; ++n)
{
sendSingleObject(obj, n, type);
}
return 0;
}
else
{
return sendSingleObject(obj, instId, type);
}
}
else if (type == TYPE_OBJ_REQ)
{
return sendSingleObject(obj, instId, TYPE_OBJ_REQ);
}
else if (type == TYPE_ACK)
{
if ( instId != UAVOBJ_ALL_INSTANCES )
{
return sendSingleObject(obj, instId, TYPE_ACK);
}
else
{
return -1;
}
}
else
{
return -1;
}
}
/**
* Send an object through the telemetry link.
* \param[in] obj Object handle to send
* \param[in] instId The instance ID (can NOT be UAVOBJ_ALL_INSTANCES, use sendObject() instead)
* \param[in] type Transaction type
* \return 0 Success
* \return -1 Failure
*/
static int32_t sendSingleObject(UAVObjHandle obj, uint16_t instId, uint8_t type)
{
int32_t length;
int32_t dataOffset;
uint32_t objId;
// Setup type and object id fields
objId = UAVObjGetID(obj);
txBuffer[0] = SYNC_VAL; // sync byte
txBuffer[1] = type;
// data length inserted here below
txBuffer[4] = (uint8_t)(objId & 0xFF);
txBuffer[5] = (uint8_t)((objId >> 8) & 0xFF);
txBuffer[6] = (uint8_t)((objId >> 16) & 0xFF);
txBuffer[7] = (uint8_t)((objId >> 24) & 0xFF);
// Setup instance ID if one is required
if (UAVObjIsSingleInstance(obj))
{
dataOffset = 8;
}
else
{
txBuffer[8] = (uint8_t)(instId & 0xFF);
txBuffer[9] = (uint8_t)((instId >> 8) & 0xFF);
dataOffset = 10;
}
// Determine data length
if (type == TYPE_OBJ_REQ || type == TYPE_ACK)
{
length = 0;
}
else
{
length = UAVObjGetNumBytes(obj);
}
// Check length
if (length >= MAX_PAYLOAD_LENGTH)
{
return -1;
}
// Copy data (if any)
if (length > 0)
{
if ( UAVObjPack(obj, instId, &txBuffer[dataOffset]) < 0 )
{
return -1;
}
}
// Store the packet length
txBuffer[2] = (uint8_t)((dataOffset+length) & 0xFF);
txBuffer[3] = (uint8_t)(((dataOffset+length) >> 8) & 0xFF);
// Calculate checksum
txBuffer[dataOffset+length] = updateCRC(0, txBuffer, dataOffset+length);
// Send buffer
if (outStream!=NULL) (*outStream)(txBuffer, dataOffset+length+CHECKSUM_LENGTH);
// Update stats
++stats.txObjects;
stats.txBytes += dataOffset+length+CHECKSUM_LENGTH;
stats.txObjectBytes += length;
// Done
return 0;
}
/**
* Send a NACK through the telemetry link.
* \param[in] objId Object ID to send a NACK for
* \return 0 Success
* \return -1 Failure
*/
static int32_t sendNack(uint32_t objId)
{
int32_t dataOffset;
txBuffer[0] = SYNC_VAL; // sync byte
txBuffer[1] = TYPE_NACK;
// data length inserted here below
txBuffer[4] = (uint8_t)(objId & 0xFF);
txBuffer[5] = (uint8_t)((objId >> 8) & 0xFF);
txBuffer[6] = (uint8_t)((objId >> 16) & 0xFF);
txBuffer[7] = (uint8_t)((objId >> 24) & 0xFF);
dataOffset = 8;
// Store the packet length
txBuffer[2] = (uint8_t)((dataOffset) & 0xFF);
txBuffer[3] = (uint8_t)(((dataOffset) >> 8) & 0xFF);
// Calculate checksum
txBuffer[dataOffset] = updateCRC(0, txBuffer, dataOffset);
// Send buffer
if (outStream!=NULL) (*outStream)(txBuffer, dataOffset+CHECKSUM_LENGTH);
// Update stats
stats.txBytes += dataOffset+CHECKSUM_LENGTH;
// Done
return 0;
}
/**
* Update the crc value with new data.
*
* Generated by pycrc v0.7.5, http://www.tty1.net/pycrc/
* using the configuration:
* Width = 8
* Poly = 0x07
* XorIn = 0x00
* ReflectIn = False
* XorOut = 0x00
* ReflectOut = False
* Algorithm = table-driven
*
* \param crc The current crc value.
* \param data Pointer to a buffer of \a data_len bytes.
* \param length Number of bytes in the \a data buffer.
* \return The updated crc value.
*/
static uint8_t updateCRCbyte(uint8_t crc, const uint8_t data)
{
return crc_table[crc ^ data];
}
static uint8_t updateCRC(uint8_t crc, const uint8_t* data, int32_t length)
{
// use registers for speed
register int32_t len = length;
register uint8_t crc8 = crc;
register const uint8_t *p = data;
while (len--)
crc8 = crc_table[crc8 ^ *p++];
return crc8;
}
/**
* @}
* @}
*/