Ameba MicroPython: Getting Started with RTL8722

Required Environment

AmebaD RTL8722CSM/RTL8722DM MicroPython SDK currently supports Windows 10 and Linux operating systems.

Introduction to AmebaD RTL8722CSM/RTL8722DM

Ameba is an easy-to-program platform for developing all kind of IoT applications. AmebaD is equipped with various peripheral interfaces, including WiFi, BLE, GPIO, I2C, UART, SPI, PWM, ADC and so on. Through these interfaces, AmebaD can connect with electronic components such as LED, switches, manometer, hygrometer, PM2.5 dust sensors, …etc.

The collected data can be uploaded via WiFi and be utilized by applications on smart devices to realize IoT implementation.

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AmebaD and Arduino Uno have similar size, as shown in the above figure, and the pins on AmebaD are compatible with Arduino Uno.

AmebaD uses Micro USB to supply power, which is common in many smart devices.
Please refer to the following figure and table for the pin diagram and function of AmebaD.

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 PIN nameGPIO INTADCPWMUARTSPII2C
D00GPIOB_2ADC5 UART3_RX(b)  
D01GPIOB_1ADC4 UART3_TX(b)  
D02GPIOB_3ADC6    
D03GPIOB_31     
D04GPIOB_30     
D05GPIOB_28     
D06GPIOB_29     
D07NC      
D08GPIOB_22 PWM14   
D09GPIOB_23 PWM15   
D10GPIOB_21 PWM13UART0_RTS(b)SPI0_CS 
D11GPIOB_18 PWM10UART0_RX(b)SPI0_MOSI 
D12GPIOB_19 PWM11UART0_TX(b)SPI0_MISO 
D13GPIOB_20 PWM12UART0_CTS(b)SPI0_CLK 
D14GPIOA_7  UART2_TX(log)  
D15GPIOA_8  UART2_RX(log)  
D16GPIOA_25 PWM4UART3_RX(a) I2C0_SCL
D17GPIOA_26 PWM5UART3_TX(a) I2C0_SDA
D18GPIOB_7ADC3PWM17 SPI1_CS 
D19GPIOB_6ADC2  SPI1_CLK 
D20GPIOB_5ADC1PWM9 SPI1_MISO 
D21GPIOB_4ADC0PWM8 SPI1_MOSI 
D22GPIOA_28     
D23GPIOA_24 PWM3UART0_CTS(a) I2C1_SDA
D24GPIOA_23 PWM2UART0_RTS(a) I2C1_SCL
D25GPIOA_22  UART0_RX(a)  
D26GPIOA_21  UART0_TX(a)  
D27GPIOA_20     
D28GPIOA_19     

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Note: Not all sets of peripherals shown on the picture/table above are available on MicroPython, please refer to “Examples and API” section for more information.

Introduction to RTL8722 MicroPython port

Background Information

REPL stands for Read-Evaluation-Print-Loop, it is an interactive prompt that you can use to access and control your microcontroller.

REPL has been equipped with other powerful features such as tab completion, line editing, auto-indentation, input history and more. It basically functions like the classic Python IDLE but running on microcontroller.

To use REPL, simply open any serial terminal software (most common ones are teraterm, putty etc.) on your PC and connect to your microcontroller’s serial port, then set baudrate to 115200 before manually reset the board, then you will see >>> MicroPython prompt appear on the terminal. Now you may type in any Python script on REPL as long as it’s support by MicroPython and your microcontroller’s MicroPython port.

Most importantly, try to abuse “help()” function as much as possible to gain more information. For example, upon microcontroller power up and REPL shown, just type help(). You will see a help page giving you more details about this port; also if you type help(modules), it will list out all available builtin modules that are at your disposal.

Furthermore, if you want to learn more about a module, such as its API and CONSTANT available, simply type the following code and details of that module will be returned to you, help(the module of your interest).

Let’s take Pin module (GPIO) as an example:

>>> help(Pin)
object <class 'Pin'> is of type type
  id -- 
  init -- 
  value -- 
  off -- 
  on -- 
  toggle -- 
  board -- <class 'board'>
  IN -- 0
  OUT -- 1
  PULL_NONE -- 0
  PULL_UP -- 1
  PULL_DOWN -- 2

REPL Hotkeys

• Ctrl + d :
Soft reboot MicroPython will perform software reboot, this is useful when your microcontroller is behaving abnormally. This will also run scripts in ‘boot.py’ once again. Note that this will only reset the MicroPython interpreter not the hardware, all your previously configured hardware will stay the way it is until you manually hard-reset the board.

• Ctrl + e :
Paste mode Paste mode allow you to perform pasting a large trunk of code into REPL at once without executing code line by line. This is useful when you have found a MicroPython library and wish to test it out immediately by copy and paste.

• Ctrl + b :
Normal mode This hotkey will set REPL back to normal mode. This is useful if you are stuck in certain mode and cannot get out.

• Ctrl + c :
Quick cancel This hotkey help you to cancel any input and return a new line.

Setting up Development Environment

Step 1: Setting up Development Environment

First, connect AmebaD to the computer via Micro USB:

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If this is the first time you connect AmebaD to your computer, the USB driver for AmebaD will be automatic installed.
If you have driver issue of connect board to your computer please go to https://ftdichip.com/drivers/ for USB driver.
You can check the COM port number in Device Manager of your computer:

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Step 2. Installing the necessary tools

On Windows

For windows users, please install a serial terminal software to interact with MicroPython. The most common serial terminals are Tera Term and Putty, here we recommend using Tera Term, which can be downloaded from internet.

For advanced developer who wish to compile MicroPython firmware from scratch, then please be sure to install Cygwin, which is a Linux-like environment running on Windows system. When selecting the Cygwin installer, we recommend using the Cygwin 32-bit version. During Cygwin installation, installer will prompt user if wish to install other software, please make sure to select the GNU version of make from the Devel category (see picture below) and pick the latest edition.

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Also, Python3 is required during firmware compilation, so be sure to download the latest Python3 from its official website and have it added as environment variable when asked during installation.

On Linux

For Linux user, please install a serial terminal software of your choice using apt-get install command. Here we recommend using picocom for its lightweight.

For advanced developer interested in developing MicroPython module in C, please make sure the GNU make of at least version 3.82 or newer and Python3 are installed and can be found using terminal.

Upload Firmware into Ameba

Step 1. Navigate to “Release” folder

After downloading the MicroPython repository from Github, you will notice a “Release” folder in the root directory of this repository, enter this folder and locate a tool named “Double-Click-Me-to-Upload”.

Step 2. Enter UART Download mode

To do this, first press and hold the UART_DOWNLOAD button, then press the RESET button. If success, you should see a green LED flashing on your ameba.

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Step 3. Run “Double-Click-Me-to-Upload”

As the name suggested, double click on the file to run it, follow instructions printed on the screen to update the ameba’s serial COM port (this is known to us during the driver installation step mentioned above) so the uploading can be carried out successfully. Once the uploading is successful, you will see a line of log printed on the screen – “All images are sent successfully”.

Try the First Example

Step 1. Open REPL

REPL stands for Read, Evaluate, Print and Loop, it is the MicroPython’s terminal for user to control the microcontroller. REPL is running on LOG UART, thus we need to open our serial terminal software, in this case, Tera Term to see REPL.

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Once Tera Term is opened, select “Serial” like in the picture above and choose your ameba’s serial port using the dropdown list, after that, hit “OK”. If your serial terminal is not configured to 115200 baud rate, now is the time to change it to 115200 and leave the rest of settings as default.

Now that the serial port is connected, press the RESET button once on your ameba and you should see the MicroPython’s welcome page as shown below.

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What happened here was that your Ameba first check its calibration data and then boot into MicroPython’s firmware, MicroPython then run the “boot.py” python script and imported builtin libraries.

Now, you can simply type help() to see more information, and type help(modules) to check all readily available libraries.

Step 2. Run WiFi Scan example

As most of peripherals’ examples requires additional hardware to show the example is working, we will just use WiFi Scan example as our first example and to see how easy it is to control WiFi using MicroPython.

Now, please follow along by copy+paste the following code or manually typing them out into Tera Term and hit “Enter”.

from wireless import WLAN
wifi = WLAN(mode = WLAN.STA)
wifi.scan()

You should be able to see the returned result with all discovered wireless network in your surrounding.

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Please confirm that QQ communication software is installed