More Constellations

Receivers that use GPS plus Galileo, GLONASS and BeiDou see more satellites, fix faster and stay accurate between buildings and trees. The NEO-6M is GPS-only; the u-blox M10 and BN-880 use several systems.

Fast Re-Fixes

A cold start can take a minute or more. Modules with a backup battery or supercapacitor keep satellite data, so they re-fix in seconds after waking, which matters for battery trackers that sleep between readings.

The Right Cellular Technology

NB-IoT / LTE-M: lowest power and best indoor reach, but needs carrier support. LTE Cat-1: works on regular 4G with modest data rates. Cat-4: faster, for cameras and larger uploads. 2G: only where it still exists.

Regional Bands

Modem versions differ by region (for example “G” for global, “E” for Europe). Check that the bands your carrier uses are supported before buying.

Power Supply

Modems pull short bursts of up to about 2 A. A lithium cell with a good holder or a stout regulator plus a large capacitor avoids resets; a USB port or thin wires usually can’t keep up.

Where NB-IoT isn’t available, LTE Cat-1 works on ordinary 4G networks with a regular data SIM, and Waveshare’s board pairs it with the newer ESP32-S3. It uses an ESP32-S3R2 with 2 MB PSRAM and 16 MB flash plus a SIMCom SIM7670G module for Cat-1 data and GNSS positioning, and an onboard USB switching IC with a DIP switch lets you talk to either the ESP32 or the modem over USB. Cat-1 offers enough bandwidth for telemetry, firmware updates and small images. Its 3.6-star average (16 ratings) reflects a steeper setup than Wi-Fi boards, so follow Waveshare’s wiki closely. 12 were in stock when we checked.

GPS tells you where you are but not which way you’re facing when standing still. The BN-880 (about 4.5 stars from 233 ratings) adds an HMC5883L electronic compass to a multi-constellation receiver that tracks GPS, GLONASS and BeiDou, which makes it a favorite for autonomous rovers, boats and robot lawn mowers. Its onboard flash saves your configuration, so settings survive a power cycle. The GPS uses TTL UART and the compass uses I2C, so wire both to the ESP32. The listing notes it targets open-source flight controllers, but the standard NMEA output works with any ESP32 GPS library. The compass needs calibration and should be mounted away from motors and steel.

The ATGM336H is a popular low-cost alternative to the NEO-6M that tracks both GPS and BeiDou, so it typically sees more satellites and fixes faster in partially blocked views. This Teyleten 2-pack (about 4.6 stars from 143 ratings) is marketed as a drop-in replacement for NEO-6M and NEO-M8N modules: the same UART wiring and standard NMEA output, so existing TinyGPSPlus code works unchanged. It’s a great value pick for a pair of trackers or a GPS clock plus a spare.

The NEO-6M has been the default hobby GPS module for over a decade, and HiLetgo’s GY-NEO6MV2 is the most-reviewed GPS on this list (about 4.2 stars from 307 ratings). It runs from 3–5 V, outputs NMEA at 9600 baud by default, and includes a ceramic patch antenna plus an EEPROM and backup battery that help it re-fix quickly after a short power-off. Nearly every ESP32 GPS tutorial uses it. It’s GPS-only and older than the M10 and ATGM336H, so it’s slower to fix in difficult spots, but it’s reliable outdoors with a clear sky. Only 7 were in stock when we checked.

Ordinary GPS is accurate to a few metres. With RTK corrections from a base station or an NTRIP service, the u-blox ZED-F9P reaches centimetre-level accuracy, which opens up robot mowers, precision agriculture, surveying and autonomous rovers. SparkFun’s breakout (about 4.6 stars from 17 ratings) adds an SMA connector, Qwiic I2C plus UART, and 3.3 V logic, and SparkFun’s u-blox library supports the ESP32 directly. The ESP32’s Wi-Fi or a cellular modem can fetch corrections from an NTRIP caster and feed them to the receiver. It needs a multi-band (L1/L2) GNSS antenna, sold separately. Only 2 were left when we checked.

For projects that move more data, such as ESP32 camera uploads or gateways, the SIM7600G-H offers LTE Cat-4 with global band support and fallback to 3G and 2G, plus GNSS. Waveshare’s board (about 3.7 stars from 30 ratings) is designed as a Raspberry Pi HAT, but it exposes the modem’s UART on headers, so it can be wired to an ESP32’s spare UART and driven with AT commands or TinyGSM’s SIM7600 support. Give it its own 5 V supply capable of the modem’s transmit peaks. It’s bulkier than an all-in-one board, but the global bands make it a safe choice for projects that ship to different countries. 8 were in stock when we checked.

The tiny SIM800L (about 4.2 stars from 135 ratings) is the cheapest way to send SMS alerts or small amounts of GPRS data from an ESP32, for example a text when a freezer warms up or a gate opens. The catch is significant: it’s a 2G-only modem, and 2G networks have been shut down in many countries, including the United States, so confirm 2G service exists where you’ll use it before buying. It also needs a supply of about 3.7–4.2 V that can deliver 2 A peaks; powering it from the ESP32’s 3.3 V or 5 V pins is the most common reason it keeps rebooting. A lithium cell or a dedicated regulator with a large capacitor works well.

Small ceramic antennas struggle inside metal enclosures, cars and buildings. An active external antenna mounted with a clear view of the sky fixes that, and Bingfu’s waterproof puck (about 4.6 stars from 857 ratings) is a popular choice for vehicles and outdoor boxes. It uses an SMA male connector; most hobby GPS modules and the LILYGO and Waveshare boards use u.FL/IPEX, so add an SMA-female-to-u.FL pigtail. Active antennas need DC bias from the module (most GPS modules supply it). Only 3 were left in stock when we checked.

Low-power tracker with NB-IoT coverage?

The LILYGO T-SIM7000G.

Only regular 4G available?

The Waveshare ESP32-S3 SIM7670G, or the SIM7600G-H for more speed.

GPS logger or clock?

The u-blox M10 module, or an ATGM336H pair on a budget.

Rover that needs heading?

The BN-880 GPS and compass.

Mower or survey accuracy?

The ZED-F9P RTK with a multi-band antenna and NTRIP corrections.

GPS inside a car or metal box?

Add the Bingfu active antenna and a u.FL pigtail.

Why won’t my GPS module get a fix indoors?

GPS signals are extremely weak and barely penetrate roofs and walls. Test outdoors or at a window with a clear view of the sky, allow a minute or more for the first fix, and use an external active antenna for enclosures, vehicles and indoor installs.

What SIM card do I need for NB-IoT or LTE-M?

Usually an IoT data SIM from a provider that supports NB-IoT or LTE-M on a carrier in your area; ordinary phone SIMs often aren’t provisioned for these networks. Check the provider’s coverage map for the exact technology and bands before deploying.

Which library should I use for cellular modems?

In Arduino, TinyGSM supports many SIMCom modems (including the SIM800, SIM7000 and SIM7600 families) and provides a standard network client, so MQTT and HTTP libraries work over cellular. In ESP-IDF, Espressif’s esp_modem component handles AT commands and PPP. Check that your exact modem model is supported.

Why does my cellular module keep resetting?

Almost always power. Modems draw short bursts of up to about 2 A when transmitting, which collapses weak supplies. Power the modem from a lithium cell or a regulator rated well above 2 A, add a large low-ESR capacitor close to the module, and keep supply wires short and thick. Our ESP32 power guide covers suitable parts.

Cellular or LoRa for a remote ESP32 sensor?

Cellular works anywhere with mobile coverage and needs no gateway, but requires a SIM and a data plan. LoRa is free to use and very low power, but you need your own gateway or a nearby LoRaWAN network, and range depends on terrain. For off-grid messaging, see our ESP32 LoRa and Meshtastic guide.