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Pins

Control currents in Pins for analog/digital signals, servos, i2c, …

digital readpinP0
digitalReadPin
Read the specified pin or connector as either 0 or 1.
0digital writepinP0to
digitalWritePin
Set a pin or connector value to either 0 or 1.
analog readpinP0
analogReadPin
Read the connector value as analog, that is, as a value comprised between 0 and 1023.
1023analog writepinP0to
analogWritePin
Set the connector value as analog.
20000analog set periodpinP0to (µs)
analogSetPeriod
Configure the pulse-width modulation (PWM) period of the analog output in microseconds.
00102304mapfrom lowfrom highto lowto high
map
Map a number from one range to another.
onpinP0pulsedhigh
onPulsed
Configure the pin as a digital input and generate an event when the pin is pulsed either high or low.
pulse duration (µs)
pulseDuration
Get the duration of the last pulse in microseconds.
pulse in (µs)pinP0pulsedhigh
pulseIn
Return the duration of a pulse at a pin in microseconds.
set pullpinP0toup
setPull
Configure the pull directiion of of a pin.
00analog pitchfor (ms)
analogPitch
Emit a plse-width modulation (PWM) signal to the current pitch pin.
analog set pitch pinP0
analogSetPitchPin
Set the pin used when using analog pitch or music.

Servos

180servo writepinP0to
servoWritePin
Write a value to the servo, controlling the shaft accordingly.
1500servo set pulsepinP0to (µs)
servoSetPulse
Configure the IO pin as an analog/pwm output and set a pulse width.

I2C

0falsei2c read numberat addressof formatInt8LErepeated
i2cReadNumber
Read one number from 7-bit I2C address.
00falsei2c write numberat addresswith valueof formatInt8LErepeated
i2cWriteNumber
Write one number to a 7-bit I2C address.

SPI

0spi write
spiWrite
Write to the SPI slave and return the response.
1000000spi frequency
spiFrequency
Set the SPI frequency.
83spi formatbitsmode
spiFormat
Set the SPI bits and mode.
spi set pinsMOSIP0MISOP0SCKP0
spiPins
Set the MOSI, MISO, SCK pins used by the SPI connection.

See Also

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All the bits and pieces that make up the BBC micro:bit

micro:bit board layout

LED Screen and Status LED

The red lights are LEDs (light emitting diodes) and form a 5 x 5 LED Screen. They can be set to on/off and the brightness can be controlled.

The yellow light on the back of the micro:bit is the status LED. It flashes yellow when the system wants to tell the user that something has happened.

See how the micro:bit shows numbers, text, and displays images by watching this video about LEDs:

 

Buttons

Buttons A and B are a form of input. When you press a button, it completes an electrical circuit. The micro:bit can detect either of its two buttons being pressed/released and be programmed to act on these events.

Button R on the back of the micro:bit is a system button. It has different uses. When you have downloaded and run your code onto your micro:bit, press Button R to restart and run your program from the beginning.

Find out how buttons provide input to the micro:bit in this video:

 

USB connection

When you plug in your micro:bit via USB, it should appear as a MICROBIT drive.

If you accidentally hold down the reset button as you’re plugging in your micro:bit, the micro:bit will appear as a MAINTENANCE drive instead of MICROBIT. This is known as maintenance mode.

To continue programming your micro:bit YOU MUST unplug your USB and reconnect it. Check that the drive now shows as MICROBIT.

Open the version file

Use with caution! If you click on the drive while it shows the MAINTENANCE label, you can see which version of firmware you have running on your micro:bit. Firmware on your micro:bit should be up-to-date already. You can find the version of firmware in the ‘version.txt’ file on the micro:bit. See the micro:bit firmware page for more about checking your board’s firmware version.

Compass

The compass can detect magnetic fields such as the Earth’s magnetic field. As the micro:bit has this compass, it is possible to detect the direction it is moving in. The micro:bit can detect where it is facing and movement in degrees. This data can be used by the micro:bit in a program or be sent to another device.

Accelerometer

There is an accelerometer on your micro:bit which detects changes in the micro:bit’s speed. It converts analogue information into digital form that can be used in micro:bit programs. Output is in milli-g. The device will also detect a small number of standard actions e.g. shake, tilt and free-fall.

Watch this video to learn how the accelerometer works:

 

Pins

The pins can be a form of electrical input or output. There are labels for the input/output pins P0, P1, P2, which you can attach external sensors to such as thermometers or moisture detectors.

Light level

The screen can also be used a light level sensor (it’s a really cool trick).

Learn more about how light level is detected in this light sensor video:

 

Temperature

Temperatrue is measured on the micro:bit by detecting how hot its physical CPU material is. Since it operates nearly as cool as the air around it, the temperature it measures for itself is a good approximation for the ambient temperature (the temperature near and around it).

See how the micro:bit can detect hot or cold in this temperature sensing video:

 

Runtime

The micro:bit embodies many fundamental concepts in computer science. To learn more, read the micro:bit - a reactive system.

Sometimes, your micro:bit may display an error code. For more information, see:

How do I connect the micro:bit to my computer?

Your micro:bit can be connected to your computer via a micro USB cable. Data can be sent and received between the micro:bit and the computer so programs can be downloaded from Windows, Macs and Chromebooks onto the micro:bit via this USB data connection. Click here to read more information on how to run scripts on your micro:bit, and click here to read more about the error messages you might get.

Powering your micro:bit

When your micro:bit is connected to your computer with the micro USB, it doesn’t need another power source.
When your micro:bit isn’t connected to your computer, tablet or mobile, you will need 2 x AAA 1.5 V batteries to power it.

The pins labelled 3V and GND are the power supply pins. You can attach an external device such as a motor to these and power it using the battery or USB.

Serial Communication

The micro:bit can send and receive data via serial communication. The serial data can be transferred via USB, BLE or redirected to pins on the edge connector.

Bluetooth Low Energy (BLE) Antenna

You will see the label BLE ANTENNA on the back of your micro:bit. It is for a messaging service, so that devices can talk to each other. The micro:bit is a peripheral device which can talk to a central device like a smart phone or tablet that has Bluetooth Low Energy (BLE). The micro:bit can send signals and receive signals from a central device so another BLE device can control the micro:bit or the micro:bit can control another BLE device.

Technical Information

 

Ref. https://makecode.microbit.org/device/pins

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micro:bit pins

The micro:bit pins

The micro:bit has 25 external connections on the edge connector of the board, which we refer to as ‘pins’. The edge connector is the grey area on the right side of the figure above.

There are five large pins, that are also connected to holes in the board labelled: 0, 1, 2, 3V, and GND. And along the same edge, there are 20 small pins that you can use when plugging the micro:bit into an edge connector.

Large pins

You can easily attach crocodile clips or 4mm banana plugs to the five large pins.

The first three, labelled 0, 1 and 2 are flexible and can be used for many different things - which means they are often called ‘general purpose input and output’ (shortened to GPIO). These three pins also have the ability to read analogue voltages using something called an analogue-to-digital converter (ADC). They all have the same function:

  • 0: GPIO (general purpose digital input and output) with analogue to digital convertor (ADC).
  • 1: GPIO with ADC
  • 2: GPIO with ADC

The other two large pins (3V and GND) are very different!

Watch out! The pins labelled 3V and GND relate to the power supply of the board, and they should NEVER be connected together. For details on the power, current and voltage limitations of the board, see Power Supply

power input: If the micro:bit is powered by USB or a battery, then you can use the 3V pin as a power output to power peripherals with.

  • 3V: 3 volt power output or power input. (1) power output: If the micro:bit is powered by USB or a battery, then you can use the 3V pin as a power output to power peripherals with; (2) power input: If the micro:bit is not being powered by USB or battery, you can use the 3V pin as a power input to power the micro:bit
  • GND: attaches to ground in order to complete a circuit (required when using the 3V pin)

If you hold the ‘GND’ pin with one hand, you can program the microbit to detect yourself touching the 0,1 or 2 pins with your other hand, giving you three more buttons to experiment with (you just used your body to complete an electrical circuit).

Small pins

There are 20 small pins numbered sequentially from 3-22 (these pins are not labeled on the micro:bit, however, they are labelled in the picture above).

Unlike the three large pins that are dedicated to being used for external connections, some of the small pins are shared with other components on the micro:bit board. For example, pin 3 is shared with some of the LEDs on the screen of the micro:bit, so if you are using the screen to scroll messages, you can’t use this pin as well.

  • pin 3: GPIO shared with LED Col 1 of the LED screen; can be used for ADC and digital I/O when the LED screen is turned off.
  • pin 4: GPIO shared with LED Col 2 of the LED screen; can be used for ADC and digital I/O when the LED screen is turned off.
  • pin 5: GPIO shared with Button A. This lets you trigger or detect a button “A” click externally. This pin has a pull-up resistor, which means that by default it is at voltage of 3V. To replace button A on the micro:bit with an external button, connect one end of the external button to pin 5 and the other end to GND. When the button is pressed, the voltage on pin 5 is pulled down to 0, which generates a button click event.
  • pin 6: GPIO shared with LED Col 9 of the LED screen; can be used for digital I/O when the LED screen is turned off.
  • pin 7: GPIO shared with LED Col 8 of the LED screen; can be used for digital I/O when the LED screen is turned off.
  • pin 8: Dedicated GPIO, for sending and sensing digital signals.
  • pin 9: GPIO shared with LED Col 7 of the LED screen; can be used for digital I/O when the LED screen is turned off.
  • pin 10: GPIO shared with LED Col 3 of the LED screen; can be used for ADC and digital I/O when the LED screen is turned off.
  • pin 11: GPIO shared with Button B. This lets you trigger or detect a button “B” click externally.
  • pin 12: this GPIO pin has been reserved to provide support for accessibility.
  • pin 13: GPIO that is conventionally used for the serial clock (SCK) signal of the 3-wire Serial Peripheral Interface (SPI) bus.
  • pin 14: GPIO that is conventionally used for the Master In Slave Out (MISO) signal of the SPI bus.
  • pin 15: GPIO that is conventionally used for the Master Out Slave In (MOSI) signal of the SPI bus.
  • pin 16: Dedicated GPIO (conventionally also used for SPI ‘Chip Select’ function).
  • pins 17 and 18: these pins are wired to the 3V supply, like the large ‘3V’ pad.
  • pins 19 and 20: implement the clock signal (SCL) and data line (SDA) of the I2C bus communication protocol. With I2C, several devices can be connected on the same bus and send/read messages to and from the CPU. Internally, the accelerometer and the compass are connected to i2c.
  • pins 21 and 22: these pins are wired to the GND pin and serve no other function

Ref. https://makecode.microbit.org/device/pins