131 Week 7 - Intro to Micro:bit Architecture

Question 1

Core goals of the micro:bit

Answer 1

Easy to use and encourage learning to code
Effective tool for teaching digital skills and creativity
Inspire diverse range of students Easy for students

Question 2

Requirements

Answer 2

Easy for teachers
No installation, no setup, no internet
Appeal to a range of ages
Support a range of languages
Leverage systems developed by different companies
Resource constrained

Question 3

Runtime code/software

Answer 3

Software platform that provides an environment for executing user code.
Serves as an abstraction layer that developers can use to write code.

Question 4

Microcontroller

Answer 4

A compact integrated circuit equipped with one or more CPUs and memory (flash memory and static RAM).

Question 5

Embedded system

Answer 5

An electronic product that comprises a microcontroller or multiple microcontrollers executing software instructions stored on a memory module to perform an essential function.

Question 6

USB

Answer 6

Stands for universal serial bus.
Used to power micro:bit and stream data to and from the micro:bit.

Question 7

JST connector

Answer 7

power supply (3v battery)

Question 8

Interface MCU

Answer 8

A microcontroller that handles USB connection.
Used for flashing code and Tx/Rx data to and from connected devices.

Question 9

Target/application MCU

Answer 9

A microcontroller that handles user code, runtime code and Bluetooth stack run from flash memory.
It also has custom radio capabilities. Integrated temperature sensor.

Question 10

What output devices does the micro:bit have?

Answer 10

LEDs - power and USB activity indicators (left and right of USB port respectively)
Speaker
5x5 LED matrix

Question 11

What input devices does the micro:bit have?

Answer 11

2 buttons - A and B but can detect A+B input.
Touch sensitive logo
Microphone - micro-electro mechanical system (MEMS)
5x5 LED matrix - senses ambient light
Motion sensor - accelerometer and magnetometer
Edge connector - 20 pins/strips and 5 rings for connection with external components.

Question 12

Regulator

Answer 12

Ensures voltage stays at 3.3V, suitable for powering the micro:bit. Cannot regulate if voltage is too high e.g., mains.

Question 13

Xtal

Answer 13

Electronic crystal oscillator that provides clock signal.

Question 14

SWD bus

Answer 14

Stands for serial wire debug bus.
Unidirectional bus for transferring code from interface MCU to application MCU

Question 15

UART bus

Answer 15

Stands for universal asynchronous receiver-transmitter.
Bidirectional bus that allows the MCUs to communicate.

Question 16

I²C Bus

Answer 16

Stands for Inter-integrated circuit bus.
It allows application MCU to communicate with secondary components.

Question 17

Daplink

Answer 17

Firmware on interface MCU that acts as a bride between the computer and SWD.
It presents the micro:bit as a USB disk, allowing drag-and-drop programming.

Question 18

Daplink interface mode

Answer 18

The hex file dropped onto the ‘USB disk’ is written into the target MCU flash.
USB disk name will be MICROBIT

Question 19

Daplink bootloader mode

Answer 19

The hex file dropped onto the ‘USB disk’ is written into the interface MCU flash and updates the version of DAPLink.
USB disk name will be MAINTENANCE.

Question 20

nRF5 software development kit (SDK)

Answer 20

Rich development environment for nRF51/nRF52 series MCUs.
Provides hardware abstraction and includes drivers, libraries, examples of peripherals and radio protocols.

Question 21

Component Oriented Device Abstraction Layer (CODAL)

Answer 21

Micro:bit runtime software written in C/C++.
Abstracts hardware components as software components represented by C++ classes.
Offers eventing subsystem for mapping asynchronous events to event handlers.
Can write in other languages but everything will eventually be converted to CODAL.