HSRW EOLab Wiki

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====== 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 [[https://www.az-delivery.de/en/products/az-delivery-micro-servo-sg90|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: 
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https://wiki.keyestudio.com/MB0102_Keyestudio_Microbit_Main_Board_%2BUSB_Cable%2BBattery_Holder_with_Batteries



{{https://wiki.keyestudio.com/images/thumb/8/87/4025-2.png/752px-4025-2.png?600&direct}}

{{https://wiki.keyestudio.com/images/d/d3/4025-10.png?400&direct}} {{https://wiki.keyestudio.com/images/c/c5/Mb0103-4.png?400&direct}}


===== Micro:Bit V2 Schematics =====

  * https://github.com/microbit-foundation/microbit-v2-hardware
  * {{ :eolab:projects:microbit_robot:microbit_v2.2.1_nrf52820_schematic.pdf |}}

/*  
  * {{https://github.com/microbit-foundation/microbit-v2-hardware/blob/main/V2.21/MicroBit_V2.2.1_nRF52820%20schematic.PDF}}
*/

==== Main LDO and Regulator Circuit: NCP114 ====

=== NCP114 ===

  * out: Vout = 3.3V fixed, 
  * in: Vin = 5.5V max, 
  * current: Imax = 300mA  
  * datasheet:  {{https://www.mouser.de/datasheet/2/308/1/NCP114_D-2316562.pdf|NCP114BMX330TCG}}

=== Micro:Bit Regulator Circuit ===

{{:eolab:projects:microbit_robot:regulator.png?direct&600|}}

**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 ====

  * {{https://www.st.com/resource/en/datasheet/lsm303agr.pdf}}


====== Expansion Boards / Parts ======

===== BBC micro:bit GPIO Expansion Board/Adapter =====


  * no power regulator
  * no motor drivers
  * just a buzzer
  * works for V1 and V2
  * https://www.electroschematics.com/microbit-2/

{{https://www.electroschematics.com/wp-content/uploads/2022/11/5-BBC-mb-exp_tk-2.jpg?400&direct}} {{https://www.electroschematics.com/wp-content/uploads/2022/11/6-BBC-mb-exp_tk-3.jpg?400&direct}}

===== Keystudio KS4030 =====

  * voltage regulator 5V -> 3.3V
  * logic level shifter
  * https://wiki.keyestudio.com/KS4030_Keyestudio_Microbit_Expansion_Board

{{https://wiki.keyestudio.com/images/thumb/6/6c/Ks4030-6.png/500px-Ks4030-6.png?800&direct}}

{{https://wiki.keyestudio.com/images/a/a3/Ks4030-5.png?400&direct}} {{https://wiki.keyestudio.com/images/a/a6/Ks4030-4.png?400}}


===== 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/

| {{https://www.monkmakes.com/assets/images/mb_servo_kit/everything_connected-web-1024x993.jpg?500&direct}} |
| https://www.monkmakes.com/mb_servo_kit  |

| {{https://eu.robotshop.com/cdn/shop/products/servo-controller-microbit-monk-makes_600x.jpg?500&direct}} |
| https://eu.robotshop.com/de/products/servo-controller-microbit-monk-makes | 
===== Kitronik Simple Servo Control Board =====

Original source: https://kitronik.co.uk/products/5673-kitronik-simple-servo-control-board-for-bbc-micro-bit

| {{https://kitronik.co.uk/cdn/shop/products/5673_large-kitronik-create-simple-servo-control-board-microbit_800x.jpg?500&direct}} |
| https://kitronik.co.uk/products/5673-kitronik-simple-servo-control-board-for-bbc-micro-bit |


  * Datasheet: {{https://resources.kitronik.co.uk/pdf/5673-kitronik-create-simple-servo-control-board-datasheet.pdf}}



Distributors:
  * RS Online: https://de.rs-online.com/web/p/bbc-micro-bit-add-ons/2663768
  * RobotShop: https://eu.robotshop.com/products/kitronik-simple-servo-control-board-for-bbc-microbit
  * ...


===== 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: 
\\ 
{{https://resources.kitronik.co.uk/pdf/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

{{https://kitronik.co.uk/cdn/shop/products/5694_additional-2-compact-16-servo-driver-board-microbit_800x.jpg?500&direct}}


===== 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

{{https://www.az-delivery.de/cdn/shop/products/sg90-micro-servo-motor-9g-fur-rc-roboter-hubschrauber-flugzeug-196924.jpg?400&direct}}
====== Technical Infos / Video Tutorials ======
===== Servo Motors =====

| {{youtube>yQMcr3PNxV8?}}                 |
| Servos - Funktionsweise und Eigenbauten  |

| {{youtube>v2jpnyKPH64?}}                       |
| Servos - working principle and homemade types  |

| {{youtube>kUHmYKWwuWs?}}         |
| Using Servo Motors with Arduino  |
===== Other Topics =====

| {{youtube>NsQKqehnVWk?}} |
| Funktionsweise von Kippstufen |

| {{youtube>4lFj6h-U6WI?}} |
| Flip-flop / multivibrator |

| {{youtube>P17BKTMfjSk?}} |
| Pulsweitenmodulation (PWM) |

| {{youtube>hapo4XrD5ms?}} |
| Pulse-width modulation (PWM) |