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Getting Started with Spiker:bit Block Programming

Overview​

In this guide, you’ll learn how to use your Spiker:bit and micro:bit to read muscle (EMG) and heart (ECG/EKG) signals and display them right on your micro:bit!

You’ll need:

  • 1x Spiker:bit + 1x micro:bit (inserted into the Spiker:bit front slot)
  • 3x BYB Large Muscle Electrodes
  • 1x BYB Orange Electrode Cable
  • 1x USB Cable

Reading a Muscle Signal (EMG)​

The EMG signal measures the electrical activity in your muscles.
The Spiker:bit automatically creates a variable called muscle power signal that stores this information so you can use it in your code.

Step 1: Start the Muscle Recording​

  1. Open the MakeCode editor.
  2. Drag the block “start muscle recording” into the “on start” block.
    • This sets up the micro:bit to communicate with the Spiker:bit.
    • You only need to do this once per project.

Step 2: Add Some Logic​

  1. From the Logic section, drag an “if else” block.
  2. Add a “less than” operator inside the condition.
  3. Compare the muscle power signal to a small number (like 10)

Note: The muscle activation threshold (default: 10) can be adjusted based on individual reflex strength, electrodes placements, and muscle choice. Use a lower value for weaker signals and a higher one for stronger contractions.

  1. From Basic, drag two “show icon” blocks:
    • Show a heart icon for rest
    • Show X icon for flex

Click Download

Connecting Muscles to Read an EMG Signal​

Once your Spiker:Bit is powered and ready, it’s time to connect it to a muscle and see your own electrical activity in action!

Connect two large motor electrodes along a target muscle, the forearm works best for clear, easy-to-control signals. Clip the two red leads to these electrodes, and attach the black ground to an electrode behind your hand to keep the signal clean.

Placement of Electrodes

Once the program is loaded, open Show Data to view your EMG signal in real time. Relaxed muscles stay near 0, and a firm flex can rise to around 1000, that’s your muscle’s electrical activity being measured live!

EMG Values in Action

Use this range to adjust your activation threshold (default: 10), set it lower for weaker signals and higher for stronger contractions. Finding the right value helps your readings stay stable and responsive.

Now you can use standard micro:bit code to make your EMG signal do something fun, play a sound, move a motor, or trigger lights whenever you flex. Your body’s electricity becomes your new controller! The possibilities are endless!

Reading a Heart Signal ECG​

The Spiker:bit can also record ECG signals. This requires a different electrode placement and a minor modification to the code.

Step 1: Electrode Placement for ECG​

A common placement for a simple ECG reading (based on Einthoven's triangle) is:

  1. Ground (Black Clip): Back of the left hand or wrist.
  2. Positive (Red Clip): Inside of the right wrist or forearm.
  3. Negative (Other Red Clip): Inside of the left wrist or forearm.

ECGPlacement

Step 2: Update the Code​

  1. Return to your MakeCode project.
  2. In the on start block, replace start muscle recording with the start heart recording (ECG) block.
  3. In the forever loop, replace the muscle power signal variable with the heartbeat signal (ECG) variable.
  4. Download this new program to your micro:bit.

Open the "Show Data (Device)" graph. With the electrodes properly placed, you should now see a regular, rhythmic spike corresponding to your heartbeat.

Here's what the signal will look like once you're successful:

ekgGood

Troubleshooting Note: If the spikes appear inverted (pointing down), the signal polarity is reversed.
To fix this, swap the two red alligator clips on your wrists.

ekgInverse

Note on MicroPython and JavaScript Editors​

The MakeCode editor also supports text-based coding. You can toggle between Blocks, JavaScript, and MicroPython using the tabs at the top of the editor.

Python_Java_Editor

For this demo project, the block code converted into MicroPython looks like this:

EKGPython

and JavaScript looks like this: EKGJava

Caution: Converting complex text-based code (JavaScript or MicroPython) back to the Block editor may not always work correctly and can cause data loss.
It’s best to save a separate copy of your text-based code before switching modes.

Next Steps

This guide covers the fundamentals of reading EMG and ECG signals. These same principles can be applied to control motors, trigger sounds, or interface with other hardware. For more advanced applications and project ideas, please explore the projects section of our website.