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Code Issues Releases Activity

Checksum check for nmea sentences

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git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@399 ebee16cc-31ac-478f-84a7-5cbb03baadba
This commit is contained in:
sambas 2010-03-27 13:13:39 +00:00 committed by sambas
parent 704eef119e
commit 3656caccbb
1 changed files with 45 additions and 1 deletions
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46
flight/OpenPilot/Modules/GPS/GPS.c
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@ -61,8 +61,8 @@ static int32_t addObject(UAVObjHandle obj);
static int32_t setUpdatePeriod(UAVObjHandle obj, int32_t updatePeriodMs);
// functions
void nmeaInit(void);
char* nmeaGetPacketBuffer(void);
char nmeaChecksum(char* gps_buffer);
uint8_t nmeaProcess(cBuffer* rxBuffer);
void nmeaProcessGPGGA(char* packet);
void nmeaProcessGPVTG(char* packet);
@ -215,6 +215,38 @@ char* nmeaGetPacketBuffer(void)
return NmeaPacket;
}
/**
* Prosesses NMEA sentence checksum
* \param[in] Buffer for parsed nmea sentence
* \return 0 checksum not valid
* \return 1 checksum valid
*/
char nmeaChecksum(char* gps_buffer)
{
char checksum=0;
char checksum_received=0;
for(int x=0; x<NMEA_BUFFERSIZE; x++)
{
if(gps_buffer[x]=='*')
{
//Parsing received checksum...
checksum_received = strtol(&gps_buffer[x+1],NULL,16);
break;
}
else
{
//XOR the received data...
checksum^=gps_buffer[x];
}
}
//PIOS_COM_SendFormattedStringNonBlocking(COM_DEBUG_USART,"$%d=%d\r\n",checksum_received,checksum);
if(checksum == checksum_received)
return 1;
else
return 0;
}
/**
* Prosesses NMEA sentences
@ -342,6 +374,12 @@ void nmeaProcessGPGGA(char* packet)
if(packet[6]==',' && packet[7]==',')
return;
if(!nmeaChecksum(packet))
{
// checksum not valid
//PIOS_LED_Toggle(LED2);
return;
}
// tokenizer for nmea sentence
/*for ((p = strtok_r(packet, ",", &last)); p;
(p = strtok_r(NULL, ",", &last)), i++) {
@ -466,6 +504,12 @@ void nmeaProcessGPVTG(char* packet)
if(packet[6]==',' && packet[7]==',')
return;
if(!nmeaChecksum(packet))
{
// checksum not valid
//PIOS_LED_Toggle(LED2);
return;
}
// tokenizer for nmea sentence
/*for ((p = strtok_r(packet, ",", &last)); p;
(p = strtok_r(NULL, ",", &last)), i++) {