Micro:Bit Robot

We are using makecode to program the microbits.

Workarounds on Ubuntu

Unfortunately setting up the WebUSB mechanism needed to program the mircobits via USB from Chrome, Chromium or Edge on Linux is causing some trouble.

Shreya's and copilot's howto: microbit_troubleshooting.pdf

Download the .sh (bash script) file below to your Downloads folder by clicking on the blue title.

prep_microbit_on_ubuntu.sh

set -x
wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
 
apt update
apt install ./google-chrome-stable_current_amd64.deb -y
apt install google-chrome-stable -y
 
echo 'SUBSYSTEM=="usb", ATTR{idVendor}=="0d28", ATTR{idProduct}=="0204", MODE="0666"' > /etc/udev/rules.d/99-microbit.rules 
 
udevadm control --reload-rules
udevadm trigger

Then follow the steps given here:

cd ~/Downloads
chmod 755 prep_microbit_on_ubuntu.sh
sudo ./prep_microbit_on_ubuntu.sh

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?