How to print (or store) gps lat, lng value (TinyGPS++) with Bluetooth BLE nRF8001?

Question

I have a u-blox gps module and I use TinyGPS (http://arduiniana.org/libraries/tinygpsplus/) to get out the lat + lng.

If i write...

Serial.println(gps.location.lat(), 6); 

...out in the log I get the correct latvalue. Right now I however work with a BLE (https://www.adafruit.com/product/1697) and when I try to print it like this:

BTLEserial.print (gps.location.lat()`, 6); 

I get a error: no matching function for call to 'Adafruit_BLE_UART::print(double, int)'

If I do this instead, the code runs...

BTLEserial.print ((gps.location.lat(),6)); 

But I do not get the correct lat, instead I get this value 6.00000000

I have tried to store the lat like this:

double myLat;
myLat = (gps.location.lat(), 6);
BTLEserial.print (myLat);

But with that myLat also has a value of 6.00000000 which is not correct.

I tried this as well:

char sValueOne[16], sValueTwo[16];
char sBuffer[33];
strcpy(sBuffer,dtostrf(((gps.location.lat(),6)), 15, 8, sValueOne));
strcat(sBuffer,",");
strcat(sBuffer,dtostrf(((gps.location.lng(),6)), 15, 8, sValueTwo));
BTLEserial.write((uint8_t *)sBuffer, strlen(sBuffer));

But with that I still get 6.00000000. I am starting to run out of ideas now to make this work. I have tried to send it both directly and store it but nothing works successfully.

So how can I adjust the code to be able to print (or store) gps lat, lng value (TinyGPS++) with Bluetooth BLE nRF8001?

Appreciate every help and tips!

• Mikael Patel: 6.000000 is the value of ((gps.location.lat(),6)) where 6 is the last item in the list. C/C++ is a strange language. Remove all the extra () and things will look better.
• Martman: If i do BTLEserial.print (gps.location.lng(),6); i get a error: no matching function for call to 'Adafruit_BLE_UART::print(double, int)'
• Mikael Patel: Add links to the libraries you are using.
• Mikael Patel: myLat = (gps.location.lat(), 6); gives the value 6.0000 as explained above. It is not a list with the two values or a double with 6 digits.
• Martman: For gps i use TinyGPS++, this: arduiniana.org/libraries/tinygpsplus and for my BLE i use this where you can see sample code also: learn.adafruit.com/…

Answer 1

The Arduino Stream/Print classes may sometime need some extra attention.

BTLEserial.println(gps.location.lat()`, 6); 

The member function is available in the class Print but gets "hidden". You can help the compiler to find it with a prefix:

BTLEserial.Print::println(gps.location.lat()`, 6); 

Cheers!

• Martman: Hey! Thanks for this answer. Will try it in an hour
• Martman: Hi! I get the correct value. However, it seems like it sends one number at a time. So when I recieve this on the app the value gets chopped up. So for example if the latitude is: 32.123456, it comes like this to the app: 3, new row, 2, new row etc.
• Martman: I do not use println btw, instead print
• Mikael Patel: That is a new question! Acknowledge the answer and ask a new one. I can help you with that :)
• Martman: Ok Mikael! I will create a new thread regarding that issue. Thanks a lot for your example above to get the first part of the problem fixed. Will accept your answer and of course also upvote it!