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Table of Contents
Micro:Bit Robot
Goal
Building our own micro:bit robot kit.
Requirements:
- powered by a mini 5V USB powerbank (e.g. 2000 - 3000 mAh),
- The Micro:Bit power input is 3.3V regulated, via the 3V skrew connector (conductive holes),
- driving two SG90 micro servo motors (360°) with wheels (not the yellow DC motors), powered by 5V
- level shifter for the servo control signal from Micro:Bit 3.3V to 5V for the servos
- driving at least one additional servo motor (360° or 180°) for further action,
The Micro:Bit Board - Info from Keystudio
Pictures from the Keystudio Wiki:
https://wiki.keyestudio.com/MB0102_Keyestudio_Microbit_Main_Board_%2BUSB_Cable%2BBattery_Holder_with_Batteries
Micro:Bit V2 Schematics
Main LDO and Regulator Circuit: NCP114
NCP114
- out: Vout = 3.3V fixed,
- in: Vin = 5.5V max,
- current: Imax = 300mA
- datasheet: NCP114BMX330TCG
Micro:Bit Regulator Circuit
NOTES:
Read the annotations on the regulator schematic! The board can have FOUR power input sources.
- 5V USB via USB connector
- 3V - 4.5V via battery connector (skrew terminals)
- “lozenge” (Pastille, Raute) shaped power pad, connected to Vout of NCP114
- 3V - 5V typ. from edge connector
Findings
It is weird that the power input from the edge connector is directly connected to the voltage output pin of the LDO! Do I (rb) understand this correctly?
Compass and Accelerometer: LSM303AGR
Expansion Boards / Parts
BBC micro:bit GPIO Expansion Board/Adapter
- no power regulator
- no motor drivers
- just a buzzer
- works for V1 and V2
Keystudio KS4030
- voltage regulator 5V → 3.3V
- logic level shifter
Monk Makes Micro:Bit Servo Controller Board
ATTENTION: 180° ONLY!
Original source: https://www.monkmakes.com/mb_servo_kit
Distributors:
RS Online: https://de.rs-online.com/web/p/bbc-micro-bit-add-ons/2048260
RobotShop: https://eu.robotshop.com/products/servo-controller-microbit-monk-makes
okdo: https://www.okdo.com/de/p/servo-kit-for-microbit/
Kitronik Simple Servo Control Board
Original source: https://kitronik.co.uk/products/5673-kitronik-simple-servo-control-board-for-bbc-micro-bit
Distributors:
- …
Kitronik Compact 16 Servo Driver Board (PCA9685 I2C PWM driver IC)
Original source: https://kitronik.co.uk/products/5694-compact-16-servo-driver-board-for-the-bbc-micro-bit
Datasheet:
5694-kitronik-compact-16-servo-driver-board-for-microbit-datasheet.pdf
Features:
- Operating Voltage (Vcc): 3V to 12V
- Number of Servo channels: 16
- Servo Voltage: Same as input Voltage
- Max continuous current (all servos): 10A
SG90 Micro Servo Motor 9G
ATTENTION: 180° ONLY!
Distributors:
AZ-Delivery: https://www.az-delivery.de/en/products/az-delivery-micro-servo-sg90?variant=12236813336672
Technical Infos / Video Tutorials
Servo Motors
Servos - Funktionsweise und Eigenbauten |
Servos - working principle and homemade types |
Using Servo Motors with Arduino |
Other Topics
Funktionsweise von Kippstufen |
Flip-flop / multivibrator |
Pulsweitenmodulation (PWM) |
Pulse-width modulation (PWM) |