DeeJay wrote:What external hardware are you using to convert from the (presumed) rs232 serial output from the gpsr or laptop? (Just because the GPIO pins are labelled for use as a serial uart does not automagically convert the signal levels as well. 'Standard' rs232 serial comms do not use ttl [for the RPi, 0.0 - 3.3 volts] signal levels.)
>>This is my hardware: GARMIN 17X GPS, powered with battery (not with the Rpi). I measured the signals out of the gps receiver to be 3.3V for PPS, and signal expected on the UART RXD is about 2V. I receive the pps signal on the Rpi using "/dev/pps0" and the data stream looks correct. The serial data expected on the RXD UART of the Rpi is not seen. The rest of the hardware set up is as follows:
GPS receiver with battery power
GRD (Rpi pin #6) to GRD on GPS
UART TXD (Rpi pin #8) to Receive on GPS
UART RXD (Rpi pin #10) to TRX on GPS.
I have but not using a “RS232 Serial Port To TTL Converter Module MAX3232″.
Running "cgps -s" always times out with no data and "cat /dev/ttyAMA0" gives some type of un-readable characters (like opening a binary file with a text editor!)
Should I expect a different result if I power the GPS with the raspberry pi?