RF & Wireless

ESP32-WROOM-32 is the dual-core Xtensa LX6 classic with Wi-Fi plus classic Bluetooth and BLE, the largest ecosystem and most libraries — the safe default. ESP32-C3-MINI-1 is a newer single-core RISC-V part with Wi-Fi plus BLE 5, lower power, a smaller footprint and better long-term availability, ideal for battery sensors. ESP-12F is ESP8266-based: Wi-Fi only (no Bluetooth), fewer GPIO and less RAM, but still the cheapest option for simple Wi-Fi nodes and very widely documented. Choose ESP32 unless cost and Wi-Fi-only are the hard constraints.

The nRF24L01+ operates at 2.4 GHz with a few tens of metres indoors (up to ~100 m line-of-sight with the PA+LNA variant) and very high data rates up to 2 Mbps — it suits short-range, high-throughput links like wireless peripherals. The SX1278 uses LoRa modulation in the sub-GHz bands (433 MHz typical) with far lower data rate but kilometre-scale range and excellent obstacle penetration — it suits sensor networks, telemetry and anything long range. They are not interchangeable; pick by range-vs-bandwidth need.

SIM800L is 2G-only (GSM/GPRS) — cheap and simple, but 2G networks are being retired across Europe, North America and parts of Asia, so it is a poor choice for new long-life products. A7670E is LTE Cat-1 (10 Mbps down) with 2G fallback, the current sweet spot for most IoT telemetry. SIM7600G-H is LTE Cat-4 (150 Mbps down) with global bands and GNSS, for higher-bandwidth or worldwide deployments. All are AT-command driven over UART/USB; confirm your target carriers still support the radio technology before committing.

Genuine Espressif and SIMCom modules carry FCC/CE modular approvals that can simplify your own product certification, but you must verify the current certificate and whether your antenna/carrier configuration matches the grant. Counterfeit and clone modules are common — remarks with fake shielding-can printing, ESP32 modules loaded with only 2 MB of flash instead of 4 MB, and SIM800L clones with poor RF. We X-ray sample modules, read the actual flash size and radio ID, and inspect the shielding can laser marking on every lot before shipment.