Recommendations for GPS to direct serial interface of XBee

Thread Starter

eduncan911

Joined Nov 14, 2011
26
We've been planning a school project with my young daughter and we came up with the usage of the SUP500F GPS module directly connected to an XBee device, along with a few other sensors.

However, after trying to get an SUP500F, I've found out it's long been discontinued due to inaccuracies. I haven't been able to find a direct replacement yet; or, something I think would directly interface with an Xbee.

Would anyone have recommendations for a GPS sensor that can directly interface with the serial interface of an XBee device?

The project is designed to be ultra low-power. By utilizing the XBee sleep function, we'll power down the GPS and sensors between the long 5 minute intervals (so the plan is for). Therefore, the plan is to connect the GPS directly to the Xbee for serial data, and not utilize an Arduino nor an RPi.





* Digi XBee3 Cellular LTE-M/NB-IoT w/LTE SIM Card
* Microchip MCP1826S-3302E/AB (3.3V, TO-92 style, ~1µA) VREG (shown as 78XX in diagram)
* SUP500F GPS Sensor (that needs to be replaced)

As you can see, the concept is to directly connect the GPS sensor to the Xbee.

Thanks in advance!
 

Thread Starter

eduncan911

Joined Nov 14, 2011
26
Adafruit sell this GPS module, which might be worth looking at. I can't comment as to its compatibility with the XBee, you'll have to look at the details.
Thanks! Yes, found that earlier. Now I get to dig into the data sheets...

The XBee says about it's serial input on DIN pin 3:

The XBee 3 Cellular LTE-M/NB-IoT interfaces to a host device through a serial port. The device's serial port can communicate:
  • Through a logic and voltage compatible universal asynchronous receiver/transmitter (UART).
  • Through a level translator to any serial device, for example, through an RS-232 or USB interface board.
  • Through a serial peripheral interface (SPI) port.
It also lists more details on related pages:

* When the device is not transmitting data, the signals should idle high.
* 1200 - 230400 BAUD

Looking at that GPS module from Adafruit, it's normally a 5V device (XBee is 3.3). However, Adafruit added a voltage converter to allow it to take 3.0V or higher. So that might work.

I'll grab the data sheet of the GPS and compare. Thanks!
 

Thread Starter

eduncan911

Joined Nov 14, 2011
26
From what I can read, that GPS module defaults to 9600, 8N1. It does have 3.3V out, however it maxes at 100 mA which is no where near enough for the LTE radio on the Xbee (totals 530 mA, without BT enabled).

All of that sounds directly compatible, even the sleep mode wit the battery backup to keep a fix.

I just can't find much about if it sets HIGH when the device is not transmitting. That seems like the only last step to verify. I'll keep looking.
 
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