## Overview of AX-SIGFOX-API Electronic Components The **AX-SIGFOX-API** refers to the software interface used to control the **AX-SFEB** and **AX-SFxx** series of System-on-Chips (SoCs) manufactured by ON Semiconductor. These components are designed specifically for Ultra-Low Power (ULP) communication on the Sigfox network. --- ### 1. The Core SoC (System on Chip) The hardware underlying the API is typically the **AX-SFxx** family. These chips combine a microcontroller and a radio transceiver into a single package. | Component | Description | Function | | :--- | :--- | :--- | | **Microcontroller (MCU)** | 8-bit ultra-low power core | Executes the Sigfox stack and the AX-SIGFOX-API commands. | | **RF Transceiver** | Sub-GHz Radio | Operates in the 868 MHz (EU) or 902 MHz (US) ISM bands. | | **Flash Memory** | Internal Storage | Stores the API firmware, Sigfox ID, and PAC (Porting Access Code). | --- ### 2. Physical Interface & Connectivity To interact with the AX-SIGFOX-API from an external host (like an Arduino, STM32, or PC), specific electronic pins and protocols are used. #### Hardware Pinout Requirements * **UART (Universal Asynchronous Receiver/Transmitter):** The primary method for sending API commands. * `TX/RX` pins: Used for the AT Command set or API binary calls. * **GPIOs:** Used for signaling status, such as "Ready to Send" or "Wake-up." * **Reset Pin:** A hardware pin used to re-initialize the API and the chip state. --- ### 3. RF Front-End Components The API controls the high-frequency electronics that manage the physical signal. 1. **Matching Network:** A series of passive inductors and capacitors that ensure the impedance of the SoC matches the 50-ohm antenna. 2. **TCXO (Temperature Compensated Crystal Oscillator):** Critical for Sigfox because the protocol uses **Ultra Narrow Band (UNB)**. The API relies on the precision of this crystal to prevent frequency drift. 3. **Antenna:** Usually a PCB trace antenna or a SMA-connected whip antenna. --- ### 4. Power Management The electronic design of the AX-SIGFOX-API modules is optimized for battery life (often lasting 5-10 years). * **Supply Voltage:** Typically operates between **1.8V and 3.6V**. * **Deep Sleep Mode:** The API provides software hooks to put the electronic components into a state drawing less than **100nA**. * **TX Current:** When the API triggers a transmission, the hardware draws approximately **10mA to 50mA** depending on the output power (up to +14dBm). --- ### 5. API Programming Example (Pseudo-code) The following represents how the software API interacts with the hardware registers to send data: ```c // Initializing the AX-SFxx Hardware via API ax_sigfox_init(MODEM_EU); // Sending a 12-byte payload over the RF Front-end uint8_t data[12] = {0xDE, 0xAD, 0xBE, 0xEF}; ax_sigfox_send_frame(data, 12); // Entering Ultra-Low Power Sleep mode ax_sigfox_sleep(); ``` ---