> For the complete documentation index, see [llms.txt](https://docs.thinger.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.thinger.io/others/hardware/thinger-m2-iot-modem.md). # Thinger M2 IoT Modem The Thinger M2IoT Modem is a compact M.2-format connectivity module that combines an Espressif ESP32-PICO-D4 with a Quectel BC660K-GL NB-IoT modem and a pre-installed 1NCE eSIM, providing Wi-Fi, Bluetooth and NB-IoT in a 22 × 42 mm board.
{% hint style="warning" %} The M2IoT uses the **M.2 2242 mechanical format only**. Its pinout is **not compatible with standard M.2 slots** (for example, the ones found on laptops or SSD adapters). Use it only with carrier boards designed for this module. {% endhint %} Designed by the Thinger.io team, this module is aimed at developers, makers and industry professionals who need to add **Wi-Fi, Bluetooth and cellular NB-IoT connectivity** to their own hardware with minimal integration effort and the best compatibility with the Thinger.io platform. The ESP32 handles the application and the Wi-Fi/Bluetooth connectivity, and controls the Quectel modem through a UART and a few control lines, so the whole module can be programmed from a single processor using the Arduino Framework, ESP-IDF or MicroPython. * The **BC660K-GL** is a high-performance LTE Cat NB2 module with extremely low power consumption, supporting the frequency bands B1/2/3/4/5/8/12/13/17/18/19/20/25/28/66/70/85. It is controlled through AT commands. * The **ESP32-PICO-D4** is a System-in-Package with a dual-core Xtensa® LX6 microprocessor, Wi-Fi and Bluetooth, and integrates a 4 MB SPI flash and a 40 MHz crystal oscillator, so it requires very few external components. * The module includes a soldered **1NCE eSIM (MFF2)**, so no SIM card or SIM holder is needed to connect to the NB-IoT network. * Two **U.FL connectors** are available to attach independent antennas for Wi-Fi/Bluetooth and for NB-IoT. ### Technical Specifications | Feature | Specification | | --------------------- | ------------------------------------------------------------------------------------------- | | Form factor | M.2 2242 (22 × 42 mm), 4-layer PCB | | Processor | ESP32-PICO-D4, Xtensa® dual-core 32-bit LX6 up to 240 MHz | | Memory | 4 MB SPI flash, 520 KB SRAM, 448 KB ROM, 16 KB RTC SRAM | | WiFi | 802.11 b/g/n, 2.4 GHz, up to 150 Mbps | | Bluetooth | Bluetooth v4.2 BR/EDR and BLE | | NB-IoT modem | Quectel BC660K-GL (LTE Cat NB2) | | NB-IoT bands | B1/2/3/4/5/8/12/13/17/18/19/20/25/28/66/70/85 | | SIM | 1NCE eSIM (MFF2), soldered on board | | Antenna connectors | 2 × U.FL: WiFi-ANT (Wi-Fi / Bluetooth) and NB ANT (NB-IoT) | | GPIO | 10 configurable ESP32 GPIOs available at the connector (plus UART0 and GPIO0) | | Programming | Arduino Framework, ESP-IDF, MicroPython, through the UART0 of the ESP32 | | LEDs | NB-IoT modem power, NB-IoT network status, ESP32 UART TX, user LED | | Supported peripherals | UART, SPI, I2C, I2S, LED PWM, pulse counter, GPIO, capacitive touch sensor, ADC, DAC, TWAI® | #### Electrical Characteristics | Power source | Voltage | Current | | ------------------------------------------- | ------- | ------- | | VBUS (connector pins 1 and 2) | 5 V | TBD | | 3.3 V output (connector pins 38, 49 and 54) | 3.3 V | TBD | The 3.3 V pins are connected to the ESP32 supply rail and can be used as a reference or to power low-consumption external circuits. The supply of the NB-IoT modem is generated internally and is not available at the connector. ### Hardware overview | Element | Description | | ----------------- | ------------------------------------------------------------------------------------------------------------ | | ESP32-PICO-D4 | Main processor with Wi-Fi, Bluetooth and 4 MB of flash. It runs the user application and controls the modem. | | Quectel BC660K-GL | NB-IoT modem, connected to the ESP32 through a UART and three control lines. | | 1NCE eSIM | Soldered MFF2 eSIM connected to the BC660K-GL. | | WiFi-ANT (U.FL) | Antenna connector for Wi-Fi and Bluetooth. | | NB ANT (U.FL) | Antenna connector for NB-IoT. | #### LEDs
| LED | Indicates | Behavior | | ------------------------------ | -------------------------------------------------------- | ---------------------------------------------------------------------------------------- | | LED1 - Modem power - RED | The Quectel BC660K-GL is powered on. | On while the modem is on. | | LED2 - Network status - YELLOW | NB-IoT connection status (NETLIGHT output of the modem). | Driven by the modem. The blinking pattern depends on the modem LED mode (`AT+QLEDMODE`). | | LED3 - TX - BLUE | ESP32 UART0 transmission. | Blinks when the ESP32 sends data through UART0 (programming or serial console). | | LED4 - User - RED | Free for the user application. | Connected to GPIO21. Set GPIO21 to HIGH to turn it on. | ### Pinout
The following table shows the connections available at the M.2 edge connector. Pins that are not listed are not connected. | M.2 pin | Signal | ESP32 GPIO | Notes | | ----------------------------- | --------------- | ---------- | ------------------------------------------------------------------------------------- | | 1, 2 | VBUS | | Power input (5 V) | | 3, 25, 40, 47, 56, 63, 65, 67 | GND | | Ground | | 4 | TXD0 | GPIO1 | UART0 TX. Console and programming. | | 6 | RXD0 | GPIO3 | UART0 RX. Console and programming. | | 8 | IO0 | GPIO0 | Boot mode selection. Keep LOW at reset to enter the flash download mode. | | 10 | RESET | EN | ESP32 reset (active LOW). | | 20 | TxBC-RxESP | GPIO4 | Connected to the TXD output of the modem (ESP32 RX). Also available at the connector. | | 22 | RxBC-TxESP | GPIO13 | Connected to the RXD input of the modem (ESP32 TX). Also available at the connector. | | 24 | IO12 | GPIO12 | ADC2, touch. Strapping pin: do not drive it HIGH at boot. | | 26 | IO14 | GPIO14 | ADC2, touch | | 28 | IO27 | GPIO27 | ADC2, touch | | 30 | IO26 | GPIO26 | ADC2, DAC2 | | 32 | IO25 | GPIO25 | ADC2, DAC1 | | 34 | IO32 | GPIO32 | ADC1, touch | | 36 | IO33 | GPIO33 | ADC1, touch | | 38, 49, 54 | +3.3V | | 3.3 V output | | 42 | IO19 | GPIO19 | | | 44 | IO21 | GPIO21 | Shared with the user LED. | | 46 | IO22 | GPIO22 | | | 48 | PWRKEY | GPIO23 | Controls the power key of the modem. | | 50 | PSM\_EINT | GPIO5 | Controls the PSM\_EINT input of the modem. | | 52 | RESET\_BC | GPIO18 | Resets the modem. | | 66 | BC\_EXT\_ENABLE | | BC660 external power control | | 68 | SIM\_IO\_EXT | | SIM IO external pin | | 70 | SIM\_RST\_EXT | | SIM RST external pin | | 72 | SIM\_CLK\_EXT | | SIM CLK external pin | | 74 | SIM\_VDD | | SIM VDD | {% hint style="info" %} GPIO4, GPIO13, GPIO23, GPIO5 and GPIO18 are used internally to communicate with and control the NB-IoT modem. **Do not drive them from external hardware** if the modem is in use. {% endhint %} {% hint style="info" %} The SIM lines (pins 68, 70, 72 and 74) are connected to the on-board eSIM. Do not connect an additional SIM card to these lines. {% endhint %} #### Internal connections to the NB-IoT modem | Function | ESP32 GPIO | Description | | ------------- | ---------- | ------------------------------------------------------------------------------ | | Modem UART RX | GPIO4 | Receives data from the modem TXD pin. | | Modem UART TX | GPIO13 | Sends data to the modem RXD pin. | | PWRKEY | GPIO23 | HIGH level pulls the modem PWRKEY pin LOW (power on / power off). | | RESET | GPIO18 | HIGH level pulls the modem RESET pin LOW (hardware reset). | | PSM\_EINT | GPIO5 | HIGH level pulls the modem PSM\_EINT pin LOW (wake up from power saving mode). | The three control lines are inverted: a HIGH level in the GPIO activates the corresponding modem input. The default UART speed to communicate with the modem is 115200 baud. ### Getting Started **1. Install the Required Software** * **Arduino IDE** (with the ESP32 board manager) or **Visual Studio Code** with the **PlatformIO** extension. * Install the Thinger.io library and the TinyGSM library in the project. **2. Connect the Module** * Attach the antennas to the **WiFi-ANT** and **NB ANT** U.FL connectors. * Insert the module in a compatible carrier board and power it through VBUS. * The module does not include a USB interface. Connect a USB-UART adapter to the UART0 pins (TXD0, RXD0) of the carrier board. **3. Upload the First Sketch** * To enter the flash download mode, hold GPIO0 LOW while resetting the ESP32 (RESET pin), and then upload the sketch. * Select the **ESP32 Dev Module** board in the Arduino IDE. * Use the Thinger.io libraries to configure the **Wi-Fi or NB-IoT** connectivity in a few lines of code. ### Example code This example shows how to connect to the Thinger.io platform through the NB-IoT modem using the TinyGSM and Thinger.io libraries. To work with the Wi-Fi or Bluetooth modems, just use the common ESP32 source code. The module comes with a 1NCE eSIM, so the APN to use is `iot.1nce.net` (no user or password). ```cpp #define THINGER_SERVER "acme.thinger.io" #define THINGER_SERIAL_DEBUG #define _DISABLE_TLS_ #include // Serial for the debug console and serial for the modem #define SerialMon Serial #define SerialAT Serial1 // Select the modem #define TINY_GSM_MODEM_BC660 #define TINY_GSM_DEBUG SerialMon #ifndef TINY_GSM_RX_BUFFER #define TINY_GSM_RX_BUFFER 1024 #endif #include #include #include "arduino_secrets.h" // USERNAME, DEVICE_ID, DEVICE_CREDENTIAL // M2IoT modem pins #define PIN_MODEM_RX 4 // ESP32 RX <- modem TXD #define PIN_MODEM_TX 13 // ESP32 TX -> modem RXD #define PIN_MODEM_PWR_KEY 23 #define PIN_MODEM_RESET 18 #define PIN_MODEM_PSM 5 #define PIN_USER_LED 21 // 1NCE APN #define APN_NAME "iot.1nce.net" #define APN_USER "" #define APN_PSWD "" ThingerTinyGSM thing(USERNAME, DEVICE_ID, DEVICE_CREDENTIAL, SerialAT); void setup() { pinMode(PIN_MODEM_PWR_KEY, OUTPUT); pinMode(PIN_MODEM_RESET, OUTPUT); pinMode(PIN_MODEM_PSM, OUTPUT); pinMode(PIN_USER_LED, OUTPUT); Serial.begin(115200); SerialAT.begin(115200, SERIAL_8N1, PIN_MODEM_RX, PIN_MODEM_TX); delay(400); // set the APN thing.setAPN(APN_NAME, APN_USER, APN_PSWD); // hardware reset of the modem (a HIGH level activates the reset line) thing.setModuleReset([]{ digitalWrite(PIN_MODEM_RESET, HIGH); delay(100); digitalWrite(PIN_MODEM_RESET, LOW); }); thing.initModem([](TinyGsm& modem){ // disable power saving mode and eDRX modem.sendAT("+CPSMS=0"); modem.waitResponse(); modem.sendAT("+CEDRXS=0"); modem.waitResponse(); // enable the network status LED modem.sendAT("+QLEDMODE=1"); modem.waitResponse(); }); // user LED controlled from the platform thing["led"] << digitalPin(PIN_USER_LED); // modem information thing["modem"] >> [](pson& out){ out["modem"] = thing.getTinyGsm().getModemInfo().c_str(); out["IMEI"] = thing.getTinyGsm().getIMEI().c_str(); out["CCID"] = thing.getTinyGsm().getSimCCID().c_str(); out["operator"] = thing.getTinyGsm().getOperator().c_str(); }; } void loop() { thing.handle(); } ``` {% hint style="info" %} If the modem does not power on automatically, generate a pulse on the PWRKEY line (GPIO23) before starting the connection. The timings required by the modem are described in the Quectel BC660K-GL hardware design document. {% endhint %} {% endhint %} ### Design files #### Related documents * [Quectel BC660K-GL product page](https://www.quectel.com/product/lpwa-bc660k-gl/) * [ESP32-PICO-D4 datasheet](https://www.espressif.com/sites/default/files/documentation/esp32-pico-d4_datasheet_en.pdf) * [1NCE IoT Connectivity](https://1nce.com/) ### Use Cases 🔹 **Smart Cities & Remote Monitoring** – Low-power sensors with NB-IoT for real-time monitoring\ 🔹 **Industrial IoT (IIoT)** – Secure cloud connectivity for machinery and logistics tracking\ 🔹 **Asset tracking & Logistics** – Connectivity in locations without Wi-Fi coverage\ 🔹 **Home Automation** – Wi-Fi and cellular connectivity for smart devices\ 🔹 **Agriculture & Environment** – Remote sensing with ultra-low power requirements ### Additional considerations * This module is not designed for use in standard M.2 slots. Connecting it to a computer or a standard M.2 socket may damage the module and the host. * NB-IoT coverage and available bands depend on the country and the network operator. Check the coverage of the 1NCE network in the deployment location. * An antenna must be connected to the NB ANT connector whenever the modem is in use. **Disclaimer** This device is commercialized by INTERNET OF THINGER S.L. (Thinger.io platform) as a self-certified development kit. Consequently, it is not subject to common commercial homologation rules. The device owner is liable for all injuries to third parties and damage to their properties.