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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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
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