I’ve just dug out a couple of SR-92 GPS modules (here’s the datasheet http://www.seeedstudio.com/depot/images/product/sr-92.pdf ).
According to my reading of the datasheet, I think I need to pass the signal through a level shifter i.e. a max232.
The section on protocols says “Both NMEA and SiRF binary protocols could be supported via serial UART I/O port –
The section on pin assigment says “Port A serial data output (GPS out); N-8-1, NMEA v3.00 output” and the section entitled ‘digital output’ says “Digital I/O VIH: 2~3.15V, VIL: 0~0.85V
VOH: >2.1V, VOL< 0.72V”
Can someone please give me a 2nd opinion on this? Note - I’m only interested in reading from the GPS, not talking to it. Bearing this in mind, can I get away without the level shifter? (it’d make my circuit easier if it does)