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Propeller + Gprs Module GM862 — Parallax Forums

Propeller + Gprs Module GM862

ccastroccastro Posts: 5
edited 2013-11-25 01:46 in Propeller 1
Hello
This is a short question:
Is there a serial coupling circuit between Propeller Chip (P8X32A) and GM862 Module... If both are working with 3.5 Vdc??. I'm having a lot of troubles in the comunication, i think coupling may be a solution.


Thank you!

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-11-24 23:04
    The couple of GPS units I've used with the Prop didn't need any sort of special coupling. Many GPS units just start spitting out data once they are powered.

    What baud setting does the GPS use? What program are you using to test the GPS unit. Can you post of a photo of your wiring?
  • max72max72 Posts: 1,155
    edited 2013-11-25 00:36
    GSM units are current hungry. Check the specs..
    I had issues with SIM900 because the current peak bursts were dropping the voltage and the module shut down.
    I used a heavy duty 4V regulated voltage for the GSM module and a 3.3V for the prop. The 4V was derived from the datasheet.

    From Telit datasheet:
    RF transmission in GSM systems is not continuous, being packed into bursts at a base frequency of about 216 Hz. The relative current peaks can be as high as about 2A.

    In my experience power supply if the most critical part in GSM use.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-11-25 01:46
    max72 wrote: »
    In my experience power supply if the most critical part in GSM use.

    This reminds me of another problem I've had with GPS. I built a small GPS pedometer datalogger which worked just fine on the bench. I used a couple of Li-Ion cells to make it portable and my switching regulator severely interfere with the GPS signal. I came back home excited to see my log and found the GPS hadn't been able to establish a lock the entire time I was out walking.
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