Re: [gpsd-users] using gpsd on Cubieboard with Garmin 16x-HVS and app written in Qt

[Tom Fanning]

That Garmin has "true RS-232 output" levels

ref http://static.garmincdn.com/pumac/GPS16x_TechnicalSpecifications.pdf page 5 section 1.5.5

whatever that means - RS-232 space (0) is +3V to +15V, mark (1) is -3V to -15V

RS-232 on proper cables is good for 75 feet at 9600 baud, and empirically more.

http://www.marcspages.co.uk/tech/long232.htm

Voltage drop on good quality cables over 5m shouldn't be too bad. Might be worth measuring what actual signalling voltages that Garmin actually uses, then run the numbers, check the signal is still > 3V and < -3V (i.e. within RS-232 spec) by the time it has traversed your cables.

If you need to get commands up to the GPS, you might struggle if your UART only signals at 3.3V. You might well drop more than 0.3V over 5m, and the Garmin might not tolerate running out of spec.

Good quality cables with twisted pairs and proper shielding should stop any RFI problems.

Might just be easier to buy it and try...

On 21 March 2017 at 12:42, Marek Floriańczyk <address@hidden> wrote:

Hi all,

I need some answer/guidance if anyone is familiar with similar setup:
Microcomputer Cubieboard2 or Orange Pi plus
Garmin 16xHVS or some new model
at least 5m long cable between computer and the receiver.
Qt app using gpsd as a position source.

Will this work reliably if I connect PORT1 of the Garmin dev to 3.3 V UART on
microcomputer with cable length at least 5m ?
Or should I use usb to rs232 adapter ?
Would you recommend some newer/different model of the GPS dev to work with?
This setup is for tracking a bus in an urban environment.

Best Regards
Marek