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Log-o-matic needs logic flip - SparkFun Electronics

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Tips and questions relating to the GPS modules from SFE
By danstrider
#28012
This may be a long shot, but I need to flip the logic of the logomatic from non-inverted to inverted to match the uBlox SAM LS GPS. Don't ask how long it took to figure this one out. I can get the logomatic to work fine with the non-inverted logic on its own, also I've been reading the GPS several months now with no problems on its own too, so I know this isn't a hardware problem by any means. I combed through the logomatic code but couldn't find how or where the logic is defined. Does anyone know, can I change the logic in the logomatic software? Or, is there a hardware solution? I'm researching changing the logic of the GPS, but that is leading to dead-ends as well.

Any friends have a good answer?

Oh by the way, here's my project so you know it's not just a random question that won't ever go anywhere ... this is going on a UAV of sorts that is emulating how birds soar for hours on end: http://soaring.goosetechnologies.com

Thanks for the help.
Dan
By danstrider
#31947
Is there any interest in making an option to invert the logic? Is there a way to just do this in software so the hardware doesn't have to change?

Thanks!
Dan
By Nullz
#31965
This sounds like you have a voltage level shifting issue between TTL and RS232.

From the SFE datasheet, it looks like the Logomatic is a TTL device from 0v to 3.3v for the RX and TX pins.

Does your uBlox GPS output TTL voltages or RS232 voltages? If your uBlox GPS is RS232, then a MAX3232 will solve your issues. If your uBlox GPS is TTL @ 5v, then a simple voltage divider will do. If your uBlox GPS is TTL @ 3.3v, then please describe your setup more clearly.

How are you reading your uBlox GPS? To a PC directly to a serial port or USB-to-RS232 adapter?

Also, if your uBlox is infact RS232 voltages, you could damage the Logomatic. RS232 voltages can be from -15V to +15V.

Nullz