Using multiple SIM cards with SIMCom or Quectel modems is easy using multiplexers and a basic logic controller. Modems must support hot swap.
Notes on how to connect ESP32 with quad SPI PSRAM memory. Example ESP32 PSRAM schematic using ESP-WROOM-32 and ESP-PSRAM64.
ESP32 supports Wi-Fi, ethernet, PPPoS modem and other custom networking interfaces. Using esp_netif, you can search network interfaces.
I list some cases with using SIM commands like AT+CIMI which result in “ERROR: SIM failure”. Common problems are listed along with solutions.
Notes on using STM32 with ESP32 AT Module. The PCB Artists ESP32 AT SDIO module is loaded with SDIO AT firmware for use with IoT designs.
ESP32 4G modem interface allows you to add cellular internet connectivity to your IoT designs. Find schematics, PCB guidelines and code here.
Adding WiFi to STM32 can open up a lot of possibilities for IoT and industrial automation applications. We explore some STM32 WiFi options.
ESP32 multiple antenna designs can be good in long range applications and where link quality is important, for example, in wireless audio.
A demo of ESP32 MP3 audio playback using the PCB Artists ES8388 module. The MP3 file is fetched from an SD card connected to the ESP32.
An ESP32 Bluetooth audio player demo project based on the PCB Artists ES8388 and Espressif ESP-ADF framewor