Hello All, I want to interface Garmin GPS 18 with PIC18F4450 via RS-232 inorder to get data from the GPS (in NMEA fromat) and process it on the PIC. My question is dose the PIC have to supports NMEA protocol?! Or if anyone have the experince with GPS and PIC please let me know. Looking forward to hear from you. Regards,
There's no problem with communicating with the GPS device using the RS232 protocol. You may need a voltage level converter if the device does not provide TTL serial outputs. The USART in the PIC would not be responsible for any decoding of the data that is sent to/from it - it is just a USART! It is your job as the programmer to determine what the data means after it has been formatted into 8 or 9 bit chunks of data. You must obtain some information about the NMEA protocol and implement it yourself. I suspect the protocol is not very complex, and you will easily be able to implement a function to obtain the GPS data, but the hardware will not do this for you.
Nmea is a set of standards, the one you want is 0183. http://en.wikipedia.org/wiki/NMEA might help, see the two links nmea data is sent line by line, with the first few characters indicating what type of data is being sent, like position, speed, how many satalites its locked on to etc.. you will probably want to ignore most lines, and an external sram/flash chip would probably be usefull for any gps project.
