Making a neural network in Tinkercad from Microbits

Tinkercad and microbit neural network

In a previous post I produced a single neuron based around microbits in Tickercad - see here.

To extend this the basic ideas discussed in that the previous post where extended to three microbit joined together. In  other words a network of neurones or neural network.

Basic requirements of a neuron are

Requirements 

- By altering the bias (or w0 in the example), weights change the behaviour of switches changes.

-when switch is pressed a variable x1 or x2 is set to 1 depending on which button is pressed and when released it goes to 0. 

- if (bias+w1*x1+w2*x2)>=0 then a T for True appears of the LEDs otherwise F for False is shown.

So by selecting the weights and connecting the outputs (p2) from the microbits labelled as Red and Green in the image above as inputs to the yellow microbit 'neuron' we can form a neural network. Switches as the inputs and the screen on the yellow 'neuron' as the output of the network showing true (T) or false(F).

So to build a XOR from the 'neurons'

'hidden layer'

Red microbit had the variables w0 set to -1 and W1 set to 0 and W2 set 1

Green microbit had the variables w0 set to -1 and W1 set to 1 and W2 set 0

'output layer'

Yellow microbit had the variables w0 set to -1 and W1 set to 1 and W2 set 1

All of this can be found at https://www.tinkercad.com/things/hPV4nU0Asr5-smooth-bojo or through the link shown below:

All opinions in this blog are the Author's and should not in any way be seen as reflecting the views of any organisation the Author has any association with. Twitter @scottturneruon

Microbit Neuron - producing a single neuron using a microbit

This post is in response to a question from Carl Simmons (@Activ8Thinking) about has anyone built a microbit simple neuron.


Quick Overview

• Inputs are going to be binary
• Weighted sum is bias+W1*input1+w2*input2
• If weighted sum>=0 then the output is True (T on the LEDs) or '1'
• If weighted sum<0 then the output is False (F on the LEDs) or '0'

First attempt - A simple gate using the buttons A and B
So first attempt uses the A and B buttons on the Microbit as the two inputs and it produces T for true and F for false on the LEDs. So the weights produce an AND if the bias is changed from -2 to -1 you get an OR.

More Physical Solution for Single Neuron

So in this case the buttons are removed and P0 and P1 formed the inputs the weights are the same as in the previous example with the bias of -2 being used to produce a AND gate. Programming-wise this is a simpler solution than the previous one, no converting button presses into inputs.

Figures below show the 'neuron' in action.

First, one shows the case when both inputs are '0' ie. not connected to 3v connection. The output is False (F on the LEDs)

This figure shows when only one input is '1', the output is False.

Finally what happens when both inputs are '1', the output goes to True (T on the LEDs).

Where next?
Adapting the code so it produces a digital output and then combining them into a small network to solve a problem that a single neuron can't do the Exclusive OR (XOR).



All opinions in this blog are the Author's and should not in any way be seen as reflecting the views of any organisation the Author has any association with. Twitter @scottturneruon