Starter Kit for BBC micro:bit V2.21 GO

Specifications:

Application Processor: nRF52

The nRF52 application processor is responsible for running user programs. A complete application, including user code, runtime code, and Bluetooth stack, is loaded and executed directly from flash memory. All user-accessible GPIO pins are provided by this processor. It features an integrated 2.4 GHz radio peripheral used for Bluetooth transmission and other radio capabilities.

• Model: Nordic nRF52833
• Core Variant: 32-bit Arm Cortex-M4 processor with FPU
• Flash ROM: 512KB
• RAM: 128KB
• Clock Speed: 64 MHz
• Debug Interfaces: SWD, J0Link/OB

Bluetooth

The integrated 2.4 GHz transceiver supports Bluetooth communication through the Nordic S140 SoftDevice, providing a low-energy Bluetooth stack. This enables the Micro:bit board to connect to Bluetooth devices, including smartphones and tablets.

• Type: Bluetooth 5.1 with Bluetooth Low Energy (BLE)
• Band: 2.4 GHz ISM
• Channels: 50 channels of 2MHz, with only 40 used (0 to 39), 3 channels reserved for advertising (37, 38, 39)
• Sensitivity: -93 dBm in BLE mode
• Tx Power: -40 dBm to 4 dBm

Buttons

The two front buttons on the Micro:bit board, as well as the button on the back, are non-latching buttons. The back button is connected to the KL27 interface of the processor and the NRF52 processor for system reset purposes. This means that the application will reset regardless of the power source, whether it's USB or battery. The front buttons, A and B, can be programmed by the user for various purposes. A and B use software debouncing, which includes short-press, long-press, and simultaneous button press detection. The buttons operate in an inverted electrical mode, where the pull-up resistor provides a logic 1 when the button is not pressed and a logic 0 when the button is pressed. Both buttons, A and B, are connected to GPIO pins that are also accessible through the edge connector of the Micro:bit board.

• Type: 2 non-latching user buttons and 1 system button
• Debounce: (A & B) software debounce, 54ms period
• Pull-up (A & B): external 4.7kΩ, (System) 10kΩ

Display

The display is an array of LEDs connected to the Micro:bit board as a 5x5 matrix. Using software, this LED matrix is refreshed repeatedly at a high speed, so the user does not notice when the matrix is being refreshed. This LED matrix is also used for ambient light detection by repeatedly configuring the LED pins as input pins and measuring the voltage drop over time (the LEDs are used as photodiodes), which is approximately proportional to the ambient light level.

• Type: Miniature surface-mounted red LEDs
• Physical Structure: 5x5 matrix
• Electrical Structure: 5x5
• Intensity Control: Software-controlled from 0 to 255
• Detection: Ambient light estimation through a software algorithm
• Color Sensitivity: Centered on red, with red at 700 nm

Motion Sensor

• Model: LSM303AGR
• Features: 3-axis magnetometer and 3-axis accelerometer
• Resolution: 8/10/12 bits
• Gestures: Freefall

Temperature Sensor:

• Type: On-core NRF52
• Measurement Range: -40°C to 105°C
• Resolution: Steps of 0.25°C

Input/Output Pins:

• Rings: 3 large rings for IO and two for power, compatible with crocodile clips and 4 mm connectors
• GPIO Features:
  • 19 configurable pins
  • 2 pins dedicated to external I2C interface
  • 6 used for display or light detection function
  • 2 used for built-in buttons
  • 1 reserved for accessibility interface
  • 19 can be configured as digital input or output pins
  • 19 can be configured for up to 3 simultaneous PWM channels
  • 6 can be used as analog input pins
  • 3 can be assigned for an optional SPI interface
  • 3 can be assigned for 3 simultaneous button press detection inputs
• ADC Resolution: 10 bits (0 - 1023)

Power:

• Operating Voltage: 1.8V - 3.6V
• Operating Current (USB and battery): 300mA max
• Current for integrated peripherals: 90mA
• Battery Connector: JST X2B-PH-SM4-TB

Package Contents:

• 1 x Micro:bit
• 1 x USB cable
• 1 x Battery holder
• 2 x AAA batteries