Hi everyone,I bought an EM-406A and I connected directly the Tx pin of gps with Rx pin of AVR 8515L...the output that it gives me does not look like NMEA strings, but it gives words like this: NNNNV NN2F NNV6>>> NNNNNNN etc.As I wrote above I connect the Tx pin of GPS withe Rx Pin ogf microprocessor directly and I suspect that this is the problem...should I connect any device or filter between Tx pin and Rx pin?Any ideas?
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you can use sn7404 hex inverter to do the level shifting, can use two gates to do this,and there are six gates. this is the simplest way to do this. if you need further information I can give
I am having problems with gps readout my location is 5142 and it reads 51728. I have tried a new gps 406A readout is the same, I read the data from the G/S and terminal also ide com monitor same result, also I am pretty sure there is no such Lat 51.7 something as it only goes up to 60. any Ideas whats going on here
There are a couple of details that you need to take into account...
1. Although the EM-406A is a 5 volt part, it does not put out 5 volts on the Tx pin, its more like 3.8 volts. I am not familiar with the AVR, but if it needs more than 3.8 volts to drive the Rx line, you will need a level shifter. So, my first question is, what are the supply voltages that you are using for the GPS and for the AVR? And what is the Rx input circuit? Is it TTL or is it perhaps a CMOS Schmidt trigger? TTL will work at low voltage, but a CMOS Schmidt trigger generally requires a large voltage swing.
2. The default baud rate for the EM-406A is 4,800, so you will need to set the AVR baud rate generator for 4,800.
Replies
you can use sn7404 hex inverter to do the level shifting, can use two gates to do this,and there are six gates. this is the simplest way to do this. if you need further information I can give
There are a couple of details that you need to take into account...
1. Although the EM-406A is a 5 volt part, it does not put out 5 volts on the Tx pin, its more like 3.8 volts. I am not familiar with the AVR, but if it needs more than 3.8 volts to drive the Rx line, you will need a level shifter. So, my first question is, what are the supply voltages that you are using for the GPS and for the AVR? And what is the Rx input circuit? Is it TTL or is it perhaps a CMOS Schmidt trigger? TTL will work at low voltage, but a CMOS Schmidt trigger generally requires a large voltage swing.
2. The default baud rate for the EM-406A is 4,800, so you will need to set the AVR baud rate generator for 4,800.
Best regards,
Bill Premerlani
Have you programmed the AVR 8585L to parse the GPS data stream for the output message headers of interest (ie. RMC, GGA, etc)?
Regards,
TCIII