The basic idea

The AP6212 that comes with ART-Pi is powerful, but it cannot fully meet the needs of novices to quickly start learning stm32 IoT development. Based on this, this project introduces the easier-to-use Arduino and NodeMCU ecosystem based on ART-Pi.

1. Lead out the pins of ART-Pi and change some pins to female sockets suitable for Arduino , so that the STM32H750 high-performance embedded device can be connected to more expansion boards compatible with the Arduino ecosystem, and on this basis, it can satisfy embedded engineers' prototypes Verification and rapid development requirements; allowing embedded enthusiasts familiar with Arduino to learn STM32 related knowledge more easily; attracting more developers who love Arduino to join the ART-Pi ecosystem.
2. NodeMCU is an open source IoT platform that is developed based on the ESP8266 SDK and is compatible with Arduino hardware based on the ESP-12 series modules, such as WiFiduino. It can be programmed using Arduino IDE or Lua scripting language. The expansion board comes with an ESP12-F IoT module, which leads to the corresponding pins to the Arduino female socket and adds corresponding peripheral components , making it compatible with NodeMCU and WiFiduino, making STM32 The traditional C language embedded programming is integrated with Lua script programming and Arduino programming methods that are easy for novices to learn.
3. Lead the functional pins of ART-Pi to the corresponding pins compatible with Arduino, connect its serial port pins to the UART pins of the ESP12-F module, and connect the SPI multiplexed pins of ESP12-F with the The corresponding SPI multiplexing pins of ART-Pi are connected to enable dual-machine communication. Users are not limited to using AT commands to configure the AP6212 module that comes with ART-Pi, but can use the MCU installed in the ESP12-F module to complete more complex dual-machine collaborative applications.
4. After installing the expansion board, you can make full use of the following resources:
   • ART-Pi development board resources
   • Native support for RT-Thread real-time operating system
   • ESP-12F module that can be quickly programmed using Lua and Arduino IDE
   • Various Arduino expansion boards

Introduction to pin assignments

As shown in the picture, map the power pin and Reset pin according to the pin arrangement of Arduino UNO.

Use several pins of the STM32H750 as A0~A5; lead the GPIO of the ESP-12F module to the general-purpose pins on the right, keep the RX and TX pins of the UART connected to the corresponding UART pins of the STM32 and lead them to 0 of the corresponding Arduino UNO , Pin 1; Pins 12, 13, 14, and 15 of ESP-12F are GPIOs that support SPI multiplexing. They are lead out as IO12, 13, 14, and 15 here, and can be connected to the SPI pins of STM32 through jumpers. Switch to SPI communication mode; especially, lead out the ADC pin of ESP-12F separately.

Available scenarios

1. For beginners who are familiar with Arduino but not familiar with STM32 microcontrollers: speed up the STM32 learning process with pins that are consistent with Arduino usage habits and features that are compatible with NodeMCU
2. For network software developers who are not familiar with the underlying hardware: Provide C language collaborative development method of ArduinoIDE and RT-Thread to encapsulate the underlying hardware and speed up the project development progress
3. For embedded developers who are learning STM32 and RTOS: Introducing the Arduino ecosystem and providing a richer expansion board, which can not only obtain richer hardware resources, speed up learning, but also learn embedded development of the Internet of Things based on ESP8266. You can also learn more about RT-Thread
4. For mature embedded engineers: You can use NodeMCU's Lua language programming and ART-Pi's RT-Thread for rapid prototype verification. After verifying the idea, you can directly transfer to SDK development. After being connected to the expansion board, it is equivalent to connecting two MCUs that can communicate quickly through the SPI bus at the same time on one development board, and can use the memory management function of RT-Thread to get rid of the constraints of memory allocation, allowing developers to concentrate on implementing what they need. Function
5. For embedded hardware enthusiasts: The high performance of STM32H750 + the rich ecosystem of Arduino + the diverse functions of the ESP12-F IoT module meet the diverse needs of enthusiasts and create better works

Project examples

1. Using STM32 as the main control and relying on ESP-12F to implement a small server
2. Paired with a multimedia expansion board, use ESP-12F and AP6212 to implement a network camera and remote display
3. A smart car is implemented based on the Arduino expansion board. STM32 performs image recognition on the images captured by the smart car camera sensor. The ESP-12F module serves as the main control and obtains network remote control information from the onboard AP6212 WiFi module. Then it packages the data recognized by STM32 and passes it through ESP-12F sent to cloud server

This expansion board can also be used to connect ART-Pi and Arduino expansion boards. The effect is as shown below (connect this expansion board and SEA-S7 expansion board to ART-Pi, and you can use the FPGA computing acceleration function of SEA-S7). Powered by any USB-typec interface

Sample project

Based on RT-Thread, use RT-Thread Studio to program ART-Pi. Develop firmware for spi communication between stm32 and ESP12-F. When ESP12-F sends an IAP burning command to stm32, stm32 sends a request to the cloud through the onboard AP6212 and performs IAP burning through the serial port. The physical picture is shown in the attachment. U1 and U3 do not have components on hand, so they are replaced by resistors with the same resistance value. ;The red indicator light turns on after powering on, and the green indicator light flashes when ESP12-F is programmed, which is consistent with the Arduino programming method.

Expansion board function

ESP-12F sends instructions to stm32 and sends the current status of stm32 to the server

Baseboard function

The STM32 runs routine tasks and the LED flashes, listening to the data sent by the SPI interface. When upgrading the firmware according to the instructions of ESP12-F, the onboard AP6212 is called to send a request to the cloud to obtain the upgrade package and perform IAP burning.