The EM408 is a great product if you know the following information that’s missing in the manual:
The default protocol is SIRF
The default baud rate is 56K
You have to issue a SIRF command to get it into NEMA-4800 baud mode
The module will NOT work unless the enable/disable line is HIGH. You cannot leave it floating.
To figure this out, I had to breadboard a MAX232 circuit to the module, connect it to the PC and then run the SirF Demo program from USGlobalSat. The Demo program allows you to change the default settings which then are saved in the module so the next time you power up you are in NEMA 4800 mode.
Hope this helps everyone out there having trouble getting the EM408 to work out of the box.
BTW… if you contact USGlobalSAT Tech Support they will tell you that the default is NEMA - 4800 Baud and that the enable/disable line requires “5volts” (it’s a 3.3 volt device) to enable it. This is quite incorrect as I found out the long way…
aismail:
The EM408 is a great product if you know the following information that’s missing in the manual:
The default protocol is SIRF
The default baud rate is 56K
You have to issue a SIRF command to get it into NEMA-4800 baud mode
The module will NOT work unless the enable/disable line is HIGH. You cannot leave it floating.
To figure this out, I had to breadboard a MAX232 circuit to the module, connect it to the PC and then run the SirF Demo program from USGlobalSat. The Demo program allows you to change the default settings which then are saved in the module so the next time you power up you are in NEMA 4800 mode.
Hope this helps everyone out there having trouble getting the EM408 to work out of the box.
Amin
I just received an EM408 from Sparkfun (yesterday) and it was already set to NMEA/4800baud out of the box…
Hooked it up to my own APRS prototype board and had lock & valid NMEA data within a few seconds.
Agree that you must pullup the En/Dis line - I used a 10K to VCC (3.3V). It enters a powerdown mode if left floating or grounded - not sure how much it draws but certainly less than 1mA (resolution of the readout on my powersupply) when in powerdown. Operating current starts at around 90mA and drops to 60mA after a it has been running for a few 10’s of seconds - presumably once it has acquired lock & reached it’s “happy place”.
I’m using the builtin patch antenna and the EM408 works GREAT - acquires lock very quickly and easily holds multiple satellites inside the house. Performance seems comparable to my BT SirfIII based GPS mouse - which is what I was hoping for.
georges80:
Agree that you must pullup the En/Dis line - I used a 10K to VCC (3.3V). It enters a powerdown mode if left floating or grounded - not sure how much it draws but certainly less than 1mA (resolution of the readout on my powersupply) when in powerdown. Operating current starts at around 90mA and drops to 60mA after a it has been running for a few 10’s of seconds - presumably once it has acquired lock & reached it’s “happy place”.
how did you come up with using a 10k resistor between the VCC (3.3V) and the En/Dis line?
I have heard anything from just connecting it to the (3.3V) directly to using 1k or 10k between. but no one saying why exactly.
so I’ve got my EM-408 hooked up through a MAX233 and using a RadioShack RS232 to USB converter.
When I try using HyperTerminal to access the EM-408, it spits out constant random ASCII characters at any baud (110 to the max baud). When I run the GPSinfo program and scan the COM ports, it says “no GPS receiver” for COM5.
I’ve searched everywhere and am having a terrible time here. How do I send it the $PSRF100 command? I’m new to the scene and would appreciate any help!
All USB-to-RS232 converters are not made alike. Can you try your circuit with a native, internal, serial port? Perhaps on a 2nd PC? Failing that, can you test the converter with another, known-working, serial device?
Can you describe in detail how you have the EM-408 connected? It’s a simple enough circuit, so just describe it to us!