CH33-C - Capacitive Touch Toggle

We'll connect the Capacitive Touch Sensor with a Crazy Circuits Ribbon Cable using just three of the wires.

Start by plugging the connector with the three wires in it (Black, Red, Yellow) into the Pin 13 row of the Bit Board. (Make sure the Black wire is in - and the Yellow wire labeled S1 is closest to the number 13 on the Bit Board.) The Orange wire (labeled S2) does not get plugged in and can hang loose.

Now we'll connect the other end of the Ribbon Cable to the Capacitive Touch Sensor. S1 (Yellow) goes to IO, and then + (Positive) goes to VCC and - (Ground or Negative) goes to GND.

We used a 3D printed holder we designed to hold the Cap Touch Sensor in place on the LEGO baseplate.

(We don't have a specific holder for the Cap Touch Sensor but the 7 Segment Display Holder should work just fine.)

Alternately you can use some LEGO bricks and a rubber band or tape to hold the sensor in place. (But don't use anything conductive!)

And be sure to check out the 3D Printed Component Holder Guide if you want to design & print your own at any size.

If you've never used a micro:bit before you'll want to check out this guide: Bit Board V2 Setup and Use

We're going to load the following code for our Cap Touch Toggle program: https://makecode.microbit.org/_DazcPaWxT...

In the on start block we'll set Pin 13 to down for the Capacitive Touch Sensor, which is the opposite of what we usually do with a standard pushbutton.

We'll also set a variable named buttonValue to track if the sensor is "on" or "off".

In our first forever block we'll check for the sensor to be triggered and then check the current buttonValue. If it is 0 we'll set it to 1, and if it's 1 we'll set it to zero. (Basically a flip-flop operation.) We also pause a half second.

In our second forever loop we will test the buttonValue to see if it is 1 or not. (If it is not, we do the else part of our if/else statement.)

Once the code is loaded it should start running immediately.

You can power the micro:bit via the USB cable you used to load the code or you can use a battery pack plugged into the Bit Board.

Touch the sensor with your finger and the LED should light up. Touch it again and the LED will turn off. This is a basic toggle switch.

If you hold your finger in place on the sensor you'll see that it blinks. This is due to our code just checking for a single press and then pausing for 500 milliseconds and looping around again.

If you try to tap the sensor rapidly you'll see that it doesn't respond to quick-fire pressing. This is due to the 500 millisecond delay. (We'll deal with that in the next guide.)

As mentioned the Capacitive Touch Sensor can detect when a finger (or other conductive object being held) touches or comes close to the pad of the sensor.

In this video you can see how the sensor gets triggered by just putting a finger close to (but not touching) it, and that you can even put an object (in this case, a piece of paper) in front of the sensor.

Here's an excerpt from a post about capacitive sensors:

"The sensor works by measuring changes in an electrical property called capacitance. Capacitance describes how two conductive objects with a space between them respond to a voltage difference applied to them. When your finger, a conductive object, touches the device (screen), it changes the capacitance of the sensor."

For a more in-depth study read the full post about capacitive touch sensors.

We've got one more trick with the Capacitive Touch Sensor. If you flip it over you'll see a silver pad on the PCB (Printed Circuit Board) and we can use that to extend our reach.

Connect a piece of Maker Tape to the silver pad and run it far from the sensor. You can see in the video we made a little zig-zag pattern, but we've also successfully ran a piece of Maker Tape across a room!

In the video you'll see that we were able to trigger the sensor by just waving a hand above the Maker Tape. The tape sort of acts like an antenna to amplify the sensors reach.

One thing worth noting is that not everyone is the same! You might be able to trigger the sensor from afar while someone else needs to reach closer.

Capacitive Touch Sensors can be affected by then environment, and things like humidity, as well as from the differences between people's bodies.

Our Sound Wall project (from 2020) used a different microcontroller but could be built using a micro:bit along with a few of the Capacitive Touch Sensors and an MP3 Player.

We have a guide on using the MP3 Player with the micro:bit so it would mainly be a matter of replacing the buttons with Cap Touch sensors.

By connecting Maker Tape to the back side of the Cap Touch Sensor we can build touch points far from the micro:bit and build bigger projects with unique touch trigger capabilities.

Follow along with our recorded Live Stream!

(We'll add the video to this step after we do the stream!)