Purchased a TTL Level GPS

Thomas Fletcher · 2009-05-01 20:57

Not knowing what I was doing (as usual) I purchased a 32 Channel LS20031 GPS 5Hz Receiver that communicates via TTL. All the objects in the exchange for GPS seem to communicate at RS232. I goggled plans for converting the signal using a MAX232 chip, but before I get to deep into this I thought I might ask for advice. Has anybody used a TTL GPS with the propeller before?

Phil Pilgrim (PhiPi) · 2009-05-01 21:10

If it's TTL, it should connect directly without intervening hardware (except for series resisistors if the signal level is 5V). The MAX3232 is only needed if the GPS is RS232.

-Phil

SRLM · 2009-05-01 21:11

Isn't that just +5 v to 0V? That would be the same as the Parallax GPS, so you'll only need a series current limiting resistor.

Thomas Fletcher · 2009-05-01 21:18

That might not be my problem then. The led on the GPS is showing a lock but I am not receiving any data.

Well maybe. I am trying to use the GPS_float object with Viewport, I may be goofing something up there.


CON

_CLKMODE         = XTAL1 + PLL16x
_XINFREQ         = 5_000_000
OBJ
    vp     : "Conduit"
    gps     : "GPS_Float"
VAR
   long lat1,long1,fails


PUB main
  vp.config(string("start:dso"))
  vp.config(string("var:lat1(base=-2), long1(base=-2)"))
  vp.share(@lat1,@fails)
  gps.init
  Repeat
     lat1 := gps.Float_Latitude_Deg
     long1 := gps.Float_Longitude_Deg
     fails := gps.Long_NMEA_Counters(2)

Leon · 2009-05-01 21:33

It might be transmitting on Rx and receiving on Tx. Some GPS units do that.

Leon

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

shanghai_fool · 2009-05-01 23:28

Try a baud rate of 57600.

Timothy D. Swieter · 2009-05-02 02:28

Shanghai Fool is right, because of the unit you have and the update rate you need to adjust the baud rate of the GPS objects you are using. I have a couple similar GPSs that I bought from Taiwan and I have succesfully connected them to the Propeller but I had to change the baud rate. Also, I think the unit you are referring to has 3.3V I/O.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Timothy D. Swieter, E.I.
www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
www.tdswieter.com

Purchased a TTL Level GPS

Comments