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Fix race condition with calling lastNMEA twice in shield_sd example.

This commit is contained in:
Tony DiCola 2014-08-08 13:18:10 -07:00
parent 4b2006754e
commit ffb19795df
1 changed files with 8 additions and 5 deletions
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13
examples/shield_sdlog/shield_sdlog.ino
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@ -179,9 +179,13 @@ void loop() {
// a tricky thing here is if we print the NMEA sentence, or data // a tricky thing here is if we print the NMEA sentence, or data
// we end up not listening and catching other sentences! // we end up not listening and catching other sentences!
// so be very wary if using OUTPUT_ALLDATA and trying to print out data // so be very wary if using OUTPUT_ALLDATA and trying to print out data
//Serial.println(GPS.lastNMEA()); // this also sets the newNMEAreceived() flag to false
// Don't call lastNMEA more than once between parse calls! Calling lastNMEA
if (!GPS.parse(GPS.lastNMEA())) // this also sets the newNMEAreceived() flag to false // will clear the received flag and can cause very subtle race conditions if
// new data comes in before parse is called again.
char *stringptr = GPS.lastNMEA();
if (!GPS.parse(stringptr)) // this also sets the newNMEAreceived() flag to false
return; // we can fail to parse a sentence in which case we should just wait for another return; // we can fail to parse a sentence in which case we should just wait for another
// Sentence parsed! // Sentence parsed!
@ -194,11 +198,10 @@ void loop() {
// Rad. lets log it! // Rad. lets log it!
Serial.println("Log"); Serial.println("Log");
char *stringptr = GPS.lastNMEA();
uint8_t stringsize = strlen(stringptr); uint8_t stringsize = strlen(stringptr);
if (stringsize != logfile.write((uint8_t *)stringptr, stringsize)) //write the string to the SD file if (stringsize != logfile.write((uint8_t *)stringptr, stringsize)) //write the string to the SD file
error(4); error(4);
if (strstr(stringptr, "RMC")) logfile.flush(); if (strstr(stringptr, "RMC") || strstr(stringptr, "GGA")) logfile.flush();
Serial.println(); Serial.println();
} }
} }