The Gear You’ll Need

• Raspberry Pi Pico or Pico W – our microcontroller.

• Neo-6M GPS module – grabs your latitude/longitude from satellites.

• SIM800L GSM/GPRS module – handles sending the data over 2G.

• Antenna for each module – so they actually pick up signal.

• 2G SIM card – yes, old-school, but that’s what SIM800L likes.

• Breadboard, jumper wires, a couple of LEDs, and a steady 3.7–4.2V supply for the GSM module.

That power detail is important: SIM800L is picky and gulps down current spikes up to 2A when it transmits. A phone battery or proper buck converter works best, don’t expect the Pico’s 5V pin to keep it alive.

How It Works

Here’s the flow:

1. The GPS module spits out NMEA sentences (those $GPGGA and $GPRMC strings with coordinates and time).

2. The Pico parses that stream into something usable.

3. The SIM800L takes those numbers and shoots them off using HTTP requests.

4. A cloud service (CircuitDigest Cloud in this case) logs the data and shows it on a map.

And because the Pico has some extra smarts, it can also buffer data locally. If your GSM connection drops while you’re out of range, it just saves the GPS points and uploads them once you’re back online. That way you don’t end up with gaps in the trail.

The Modules

Neo-6M GPS:

• Cheap, reliable, and works outdoors without much fuss.

• Accuracy is around 2.5 meters in open sky.

• Talks to the Pico over UART at 9600 baud.

• If you give it a backup coin cell, it remembers satellites for faster startup.

SIM800L GSM:

• A little red board that loves 2G networks.

• Uses AT commands, you basically text instructions to it over UART like AT+CSQ (check signal) or AT+HTTPACTION=1 (send data).

• Needs an external antenna.

• Eats current like a hungry kid during transmit bursts, so again, stable power is key.

Wiring Things Up

• SIM800L TX → Pico RX (GP1)

• SIM800L RX → Pico TX (GP0)

• Neo-6M TX → Pico RX (GP5)

• Neo-6M RX → Pico TX (GP4)

• All modules share ground.

• Power goes straight from a LiPo/buck converter to the SIM800L and GPS modules.

The Pico just coordinates everything, it doesn’t have to supply the power-hungry parts.

Talking to the Cloud

Instead of reinventing the wheel, this project leans on GeoLinker API from CircuitDigest Cloud. You sign up, grab an API key, and drop it into your Pico code. Once the tracker has that, it can post coordinates straight to the server, and you get a map interface showing where it’s been.

The nice part is you don’t have to spin up your own backend or database, it’s already set up for GPS logging.

Coding

You can do this through the Arduino IDE with the RP2040 board package installed. After that, install the GeoLinker library, which comes with examples tailored for Pico + SIM800L + GPS.

The basic code flow looks like this:

• Initialize the GPS UART and SIM800L UART.

• Grab raw GPS sentences and parse them.

• Format the data into a JSON payload.

• Use the SIM800L to fire an HTTP POST to the GeoLinker endpoint.

• Handle any failures by saving data locally until it works again.

The library smooths over the nasty AT commands, so you’re mostly dealing with higher-level functions.

Testing It

Stick the whole rig near a window (GPS hates being indoors). Power it with a LiPo pack, open your CircuitDigest Cloud dashboard, and watch as points start showing up on the map. Walk around with it in your pocket and you’ll see the trail update in real time.

If things don’t work right away, common culprits are:

• SIM800L not getting enough juice.

• Wrong baud rate set for GPS.

• No valid SIM/network coverage (remember, only 2G works).

Wrap-Up

This Raspberry Pi Pico project is a neat way to build a low-cost, no-frills GPS tracker. It’s not a polished commercial gadget, but that’s the fun, you get to wire it, power it, and see exactly how the data makes its way from satellites → Pico → GSM → internet → your screen.

Once you’ve got it running, you could extend it: maybe log data to an SD card, add a small display, or tweak it to send alerts when it leaves a certain area. The foundation is solid, and the Pico makes it approachable without needing heavy hardware or complicated networking.

You will find the detailed step-by-step version of this project here: Raspberry Pi Pico GPS Tracker