I found one of the original civilian GPS units I bought way back in 1998, and remember it was seemingly very accurate with a 1 second data heartbeat. I stripped off the case/battery holder and clipped off the rusted DB-9 serial data plug.
It has a huge antenna platter (2.5 x 2.5 in) which I believe provides relatively high gain.
Im not sure what Im going to use it for other than just trying to wire it to the mega and experiment with scripts and whatnot to utilize the data stream. I read that the unit when powered doesnt transmit data until it receives an ASCII string of characters “EARTHA” or “ASTRAL” , depending on which version it is.
I havent messed with attempting to connect anything via direct serial before, outside of some established sketch or build already.
I know we have the UART and IIC pinouts, and that any I/O pin can be assigned whatever in the software…
So what would be the gravy method to pipe an archaic RS-232 serial 5-wire device like this to arduino mega R3?
Basically just combing for advice on pin-out conversion to UARTs or IIC, if not just directly interpreting the 5 wires by program code.
Ive determined the 5 colored wires from GPS are as follows…
The connector pin-out looks to be RS232 (google it for more info). This will require a TTL to RS232 level translator to connect to the Mega’s UART pins.
To first get this GPS working I would connect it to your PC’s RS232 serial port (or RS232 to USB adapter) and use a dumb terminal program (hyperterm, TeraTerm, RealTerm are a few) to find out how to communicate with the GPS.
Then write Mega code to also ‘talk’ to the PC’s serial port.
Lastly Mega code to ‘talk’ to the GPS.
Have you googled the GPS make and model number? They may be a manual and other info out there that would be helpful.
O the GPS’s serial connector, DTR and RI might just be needed to be tied together (google/Wiki has info on these handshaking lines) to get the serial to work.
There is also info on Mega code to use it’s UART on the web. Look for examples.
By doing this in steps you minimize to number of unknows which makes troubleshooting and debugging much easier.
It was the DTR and RI signal lines I was perplexed about.
Youre probably right that they can just be tied to enable flow, since thats what they do anyway in a modem capacity…duh!
I was really tired and burned out when I wrote this req, so forgive my apparent laziness.
I will build a line level converter tonite after I do the ‘obvious’ and just wire the thing like it was supposed to originally via RS-232 serial on PC to see if I can pop the initiation string to get it to start singing…
If it no worky, no use in wasting time on a dinosaur…
looked at some parallax gps today and it had all the modern goodies (20 channels) and pinouts to simplify (stupid simple) adding GPS to arduino.
Thanks mucho gracias compadre amigo buddy-o
if I hit any walls or fall in a hole I will cry for help…