Propeller-GPS communication problems.
Moskog
Posts: 554
Working with the Parallax' older GPS-receiver (#28146) I went into trouble with the I/O line. In several chematics they recommend a 1k resistor between the prop and the receiver to handle the difference of voltage levels. Because I need to use the receiver in "Smart mode" I also need to communicate in both directions. To be able to reach the satellites I hook up the gps receiver at the end of a one meter phone cord (taped the receiver to the window above my work bench). By using this 1k resistor in between, I can't communicate with the receiver. No way. I also tried to read the receivers data string (in raw mode) with a SN74LVC244, 5-3V buffer in between, without any result. Everything works fine if I connect the receiver directly to the props IO pin, but I'm not sure that will be recommended.
The GPS receiver seems to work fine with 3.3V supply too, but probably not to be trusted in all kinds of weather conditions...?
Im testing using the "first" cog but pin 31 as there are many other devices occupying the lowest IO-pins, could that affect the communication?
Could it be a better solution to supply the GPS receiver with 4V instead of 5V for less prop-pin stress?
Any suggestions?
The idea with using this GPS-receiver is to make a daily RTC time correction as my DS1302 is ticking a little too fast.
The GPS receiver seems to work fine with 3.3V supply too, but probably not to be trusted in all kinds of weather conditions...?
Im testing using the "first" cog but pin 31 as there are many other devices occupying the lowest IO-pins, could that affect the communication?
Could it be a better solution to supply the GPS receiver with 4V instead of 5V for less prop-pin stress?
Any suggestions?
The idea with using this GPS-receiver is to make a daily RTC time correction as my DS1302 is ticking a little too fast.
Comments
-Phil