I’ve had a Neo-6m (purchased here) attached to my raspberry pi b+ for several months and the GPS unit has been very reliable, however now (this week) the Red Led is flashing on the unit but the python3 code I’ve been using is now returning ’ ’ as the value when I read it in. I’ve got another unit with exactly the same config which is reading fine NEMA strings. The wiring is all good, I’ve checked the power source wiring. Any ideas?
The red light often means there is no lock. Either way, it would be best to isolate the RPI from the equation by using a Logic Analyser and inspecting the NMEA sentences that are generated. Just in case your code is not interpreting the NMEA correctly.
Failing that, an Arduino Uno or another microcontroller would be handy as well. Just be sure to power it from 3.3V (not 5V). 3.3V logic is high enough to drive the UART RX on a 5V device. Print every character on UART to the Arduino IDE console, to see exactly what is being generated.
Normally, GPS modules will be outputting data either way (lock or no lock). If it’s still returning blank with the above tests, then it could be a damaged module.