Cannot see the output sentences from the GPS unit

[versace427]

GPS help...please

I am working on building an autonomous robot with a group of people...I will be responsible for the GPS part of the project. I have the Garmin 18LVC and don't really know where to start. I'm a beginner and have no relevant experience with such projects. So far I have downloaded Teraterm and have tried to see the output sentences from the GPS unit but have yet to be successful at seeing anything....If anyone has any info as to why I may not be seeing these output senteces...I would really appreciate the help.


Thanks!
versace427

 

[IanP]

Re: GPS help...please

First check out your connection ..
Here are some hints:

Are you using pins 2 (RXD) and 3 (TXD) on the DB-9 connector to the
serial port?

And do you have DB-9 pin 5 (Ground) and the two black wires in the 18
LVC leads all on the same ground? That would normally be the negative
(-) side of the DC power source.

And is the white lead (TXD) from the 18 LVC connected to pin 2 (RXD) and
the 18 LVC green lead (RXD) to pin 3 (TXD)?

And the 18 LVC needs 4 to 5.5 Volts DC for power, right?

My first attempts at trouble shooting GPS NMEA sources almost always
involves swapping the data leads to makes sure the TXD to RXD pairs are
crossed over.

Once sure that the connection is correct, check configuration of your GPS receiver, especially how the output is set up (type = NMEA, baud rate, ...) ..

In GPS devices the typical communication speed is 4800bps so setup your computer port for that speed .. and that's basically it ..

Reards,
IanP

 

[versace427]

Re: GPS help...please

IanP,

Thank you for the help...I swopped the wires and I am now able to see the output sentences. Would you happen to have any insight on how to connect the GPS unit to a 12F675 PIC?