Weekly Assignments Final Project About me Agreement

Week06 Group Assignmnet - Compare Various Microcontrollers

micro:bit

The micro:bit is an easily programmable Single Board Computer (SBC) that contains an application processor with a variety of on-chip peripherals. Detailed information can be found at the hardware introduction page.

Basic specs of the micro:bit hardware

  • nRF52 Application Processor

  • Buttons:

    • 2 tactile user buttons, 1 tacktile system buttom

  • GPIO Pins:

    • 19 GPIO pins
    • 2 for I2C interface
    • 6 for display/light sensoing
    • 2 for button
    • 3 simultaneous PWM channels
    • 1 serial TX/RX channel
    • 6 for analog input
    • 3 for optional SPI interface
    • 3 simultaneous touch sensing inputs

  • Accelerometer and Magnetometer:

    • Model: LSM303AGR
    • 3 magnetic field and 3 acceleration axes, 2/4/8/16g ranges

  • Temperature Sensor:

    • Type: on-core nRF52
    • Sensing range: -40℃ .. 105℃

  • LED Matrix:

    • Type: minature surface mount red LED
    • Physical structure: 5x5 matrix
    • Intensity control: Software controlled up to 255 steps
    • Sensing: ambient light estimation via software algorithm
    • Sensing Range: TBC, 10 levels from off to full on

  • Bluetooth:

    • Stack: Bluetooth 5.1 with Bluetooth Low Energy(BLE)
    • Band: 2.4GHz ISM (Industrial, Scientific and Medical) 2.4GHz..2.41GHz
    • Channels: 50 2MHz channels, only 40 used (0 to 39), 3 advertising channels (37,38,39)
    • Sensitivity: -93dBm in Bluetooth low energy mode
    • Tx Power: -40dBm to 4dBm
    • Role: GAP Peripheral & GAP Central
    • Congestion avoidance: Adaptive Frequency Hopping
    • Profiles: BBC micro:bit profile

  • Power:

    • Operating range: 1.8V .. 3.6V
    • Operating current (USB and battery): 300mA max
    • On-board Peripherals budget: 90mA
    • Battery connector: JST S2D-PH-SM4-TB
    • Max current provided via edge connector: 190mA

Programming micro:bit

Micro:bit can be programmed by using the online editor(MakeCode), Mu Editor and some other editors.

The beginner friendly Web based visual block programming environment is developed by Microsoft. There're lots of examples and tutorials provided for studing and exploring the functionality of the board.

We did a little interaction program using MakeCode, the steps are documented below:

  1. Go to https://makecode.microbit.org/, click Open New Project and select the programming language, here we chosed block programming.

  2. The on shake block runs code when you shake the micro:bit. From the Basic category, get a show number block and place it inside the on shake block to display a number.

  3. Press the white SHAKE button on the micro:bit on-screen simulator, or move your cursor quickly back and forth over the simulator.

  4. But we don't want to show 0 on our dice all the time. From the Math Toolbox category, drag a pick random block and drop it into the show number block replacing the 0.

  5. A typical dice shows values from 1 to 6 dots. So, in the pick random block, change the minimum value to 1 and the maximum value to 6.

  6. Press the white SHAKE button again on the micro:bit simulator.

  7. Download！

ATmega328p

The ATmega328p is a high performance, low power AVR® 8-bit microcontroller, it is used as the core of the widely used Arduino Uno development borad. Some basic specs are listed below, more information can be found on the Microchip product page and its datasheet.

Specs

Pinout reference of ATmega328p DIP package from an alternative Arduino Core Minicore

Programming ATmega328p

The Arduino Uno comes with the USB serial interface that can be use to upload program from the computer. But the ATmega328p chip itself doesn't have that, and it needs a programmer to upload the program to the board.

Since the Arduino Uno uses the ATmega328p as its microcontroller, the Arduino IDE and its library can be used to write ATmega328p compatible code. The only difference is that the Arduino Uno has a 16MHz external crystall oscillator connected to the chip and the chip is running at a different speed if we only use the 8MHz internal oscillator of the ATmega328p itself.

According to the documentation from Arduino, we can load a diffrent board configuration for the ATmega328p to write code for the ATmega328p without the external oscillator, and we can use another Arduino Uno to act as the programmer to upload code to the chip, as some of us tried on week04 and this week's personal assignment.

Arduino Uno

Arduino Uno is a microcontroller board based on the ATmega328P (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

Below is the pin definition for the board:

The PDF of the full pinout the board can be found here.

The PCB schematics can be found here.

The datasheet can be downloaded here.

Tech specs of the Arduino Uno

Programming the Arduino Uno

Below we tried to use the Arduino Uno to make a flashing LED, the steps are:

  1. Download the latest version of the Arduino IDE, from https://www.arduino.cc/en/software.

    After installing, choose Arduino Uno in the top selection box.

  2. Write the code in the text editing area, (texts after // are comments).

    int ledPin = 10;
void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(ledPin, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(1000);                 // wait for a second
  digitalWrite(ledPin, LOW);   // turn the LED off by making the voltage LOW
  delay(1000);                 // wait for a second
}

  3. Hardware connection, Note: the two pins of the LED have different length, the longer one is +, the shorter one is -.

    The connection is shown below (1 x DFduino UNO R3, with USB cable, 1 x Prototype Shiled + breadboard, 2 x cables, 1 x 5mm LED, 1 x 200Ohm resistor):

  4. Look!

RP2040

The RP2040 is a microcontroller is designed by Raspberry Pi, product page and datasheet.

Basic specs

Seeed Xiao RP2040

The RP2040 microcontroller can also be programmed by the Arduino platform. We are using the Seeed Studio Xiao RP2040 as the develpment board for RP2040, and Seeed Studio has official documentation for programm the Xiao RP2040 via Arduino IDE.

Follow the instruction and installed the Arduino core for RP2040 to Arduino IDE, we can write code for the RP2040 microcontroller using the same set of API to control the board.

Pinout for Xiao RP2040

As the product page stated, the Xiao RP2040 has the following specs:

Due to its small formfactor, the Xiao RP2040 doesn't expose all the peripheral capabilities of the RP2040, and an error in the documentation led to some confusion when we were testing the board. (See Findings about the RP2040 Serial situation)

Seeed Studio Xiao RP2040 Schematic

ESP32

ESP32 Datasheet

The development board we have for the ESP32 chip is similiar to the official ESP32-DevKitC dev board from Espressif but with a USB Type-C connector. It has a ESP32-WROOM-32 at its core.

Use Arduino IDE to program ESP32 Dev Board

The latest version of the Arduino IDE has ESP32 platform support directly, meaning we don't have to install some other board definition file to uset the ESP32 boards.

  1. Open Arduino IDE, open the Board Manager pane, search for "esp32", and install the esp32 platform.

  2. After installing the platform, in menu select: Tools -> Board -> esp32 -> ESP32 Dev Module, then we can write code and upload to the ESP32 dev board.

    The API documentation for the ESP32 Arduino Core can be found here.