Now that you've installed WipperSnapper on your board - let's learn how to use it!

There's a large number of components (physical parts like buttons, switches, sensors, actuators) supported by WipperSnapper, but this page will get you started with the core concepts to build an IoT project with WipperSnapper.

Blink a LED

One of the first programs you typically write to get used to embedded programming is a sketch that repeatably blinks an LED. IoT projects are wireless so after completing this section, you'll be able to turn on (or off) the LED connected to the QT PY from anywhere in the world.

In this demo, we show controlling an LED from WipperSnapper. But the same kind of control can be used for relays, lights, motors, or solenoids.

Wiring

While the QT PY has a built-in NeoPixel, WipperSnapper does not (yet) support NeoPixels (we'll update this guide when it does).

To work around this, you'll build an external LED circuit connected to your QT PY.

You will need to connect the following pins to the LED and resistor:

  • QT PY GND to LED cathode (short leg)
  • QT PY Pin A2 to one leg of the 560-ohm resistor
  • LED anode (long leg) to the second leg of the 560-ohm resistor

Usage

This page assumes that you have installed WipperSnapper on your QT PY and registered it with the Adafruit.io WipperSnapper web page. If you have not done this yet, please go back to the previous page in this guide and connect your QT PY. 

On a web browser, navigate to Adafruit.io WipperSnapper. You should see your QT PY board listed on this page.

Click the image of your QT PY to navigate to its device page. 

Before the next steps, you'll want to verify that your QT PY is online and ready to receive commands from WipperSnapper. To check this, look at the online status badge on the upper left of the device page. It should be green and say Online.

If the QT PY appears offline on the website but was previously connected, press the Reset (RST) button to force the board to reboot.

Next, click + New Component to open the Component Picker.

The Component Picker lists all the available components, sensors, and parts, which can be used with WipperSnapper. 

Click the LED component

The QT PY contains GPIO pins that can be configured either as an input or an output. The "Create LED Component" screen tells WipperSnapper to configure a general-purpose output pin connected to the LED on your QT PY as a digital output so you can turn the LED on or off.

Select the A2 pin as the LED Pin and click Create Component

WipperSnapper should send a command to your board telling it to configure the GPIO pin as a digital output. Your WipperSnapper dashboard should also show the new LED component.

On the device interface, toggle the LED component by clicking the toggle switch. This should toggle the LED connected to your QT PY on or off.

Read a Push-Button

You can also configure a WipperSnapper board to wirelessly read data from standard input buttons, switches, or digital sensors, and send the state to Adafruit IO.

Let's wire up a push-button to a QT PY and configure it with WipperSnapper to publish a value to Adafruit IO when the button has been pressed or de-pressed. 

In this demo, we show reading the state of a push-button from WipperSnapper. But the same kind of control can be used for reading switches, break beam sensors, and other digital sensors.

Wiring

We'll be using the QT PY's internal pull-up resistors instead of a physical resistor. 

Make the following connections between the QT-PY and the button:

  • QT Py GND to one leg of the Push Button
  • QT Py GPIO A2 to the other leg of the Push Button

Usage

On a web browser, navigate to Adafruit.io WipperSnapper and click on your QT PY. Next, click + New Component to open the Component Picker.

From the component picker, select the Push Button.

The next screen presents you with options for configuring the push button. Start by selecting the QT PY's digital pin you connected to the push button.

The Return Interval dictates how frequently the value of the push-button will be sent from the QT PY to Adafruit IO. For this example, the push-button's value should only be sent when its pressed.

Select On Change 

Finally, check the Specify Pin Pull Direction checkbox and select Pull Up to turn on the QT PY's internal pullup resistor.

Make sure the form's settings look like the following screenshot. Then, click Create Component.

WipperSnapper should send a command to your board, telling it to configure the GPIO pin you selected to behave as a digital input pin and to enable it to pull up the internal resistor. Your WipperSnapper dashboard should also show the new push button component.

Press the button to change the value of the push button component on Adafruit IO.

Read an I2C Sensor

Inter-Integrate Circuit, aka I2C, is a two-wire protocol for connecting sensors and "devices" to a microcontroller. A large number of sensors, including the ones sold by Adafruit, use I2C to communicate. 

Typically, using I2C with a microcontroller involves programming. WipperSnapper lets you configure a microcontroller to read data from an I2C sensor and publish that data to the internet without writing code.

WipperSnapper supports a number of I2C sensors, viewable in list format here. If you do not see the I2C sensor you're attempting to use with WipperSnapper - we have a guide on adding a component to WipperSnapper here

The process of adding an I2C component to your WipperSnapper board is similar between most sensors. For this section, we're using the Adafruit AHT20, an inexpensive sensor that can read ambient temperature and humidity.

There are TWO I2C Ports on the QT-PY S2. One port is located on the SDA/SCL pins and the other is located in the STEMMA QT connector. WipperSnapper ONLY supports I2C sensors attached to the STEMMA QT connector at this time!

Wiring

First, wire up an AHT20 sensor to your board exactly as follows. Here is an example of the AHT20 wired to a QT PY using I2C with a STEMMA QT cable (no soldering required).

 

Make the following connections between the QT-PY ESP32-S2 and the AHT20 Sensor

  • Board 3V to sensor VIN (red wire on STEMMA QT)
  • Board GND to sensor GND (black wire on STEMMA QT)
  • Board SCL to sensor SCL (yellow wire on STEMMA QT)
  • Board SDA to sensor SDA (blue wire on STEMMA QT)

Scan I2C Bus

On a web browser, navigate to Adafruit.io WipperSnapper. Click on the QT PY board to enter its device page.

To ensure that you've correctly wired the AHT20 sensor to your QT PY and to test that the QT PY can communicate with Adafruit IO, you'll first perform an I2C scan. 

On the upper right-hand corner of the device interface, click Start I2C Scan.

You should see a new pop-up showing a list of the I2C addresses detected by an I2C scan. If wired correctly, the AHT20's default I2C address of 0x38 appear in the I2C scan list.

I don't see the I2C sensor's address in the list

First, double-check the connection and/or wiring between the sensor and the board.

Then, reset the board and let it re-connect to Adafruit IO WipperSnapper.

Create the Sensor Component

Now that you know the sensor can be detected by the QT PY, it's time to configure and create the sensor on WipperSnapper.

Start by clicking +New Component

The Component Picker lists all the available components, sensors, and parts that can be used with WipperSnapper. 

Under the I2C Components header, click AHT20.

On the component configuration page, the AHT20's I2C sensor address should be listed along with the sensor's settings.

The AHT20 sensor can measure ambient temperature and relative humidity. This page has individual options for reading the temperature and the relative humidity. This comes in handy in the case where you have multiple I2C sensors connected to your QT PY which read the same value. You may choose to enable or disable a specific sensor type on this page.

The Send Every option is specific to each sensor's measurements. This option will tell the QT PY how often it should read from the AHT20 sensor and send the data to Adafruit IO. Measurements can range from every 30 seconds to every 24 hours.

For this example, set the Send Every interval for both seconds to Every 30 seconds and click Create Component.

Your device interface should now show the AHT20 component you created.

After the interval you configured elapses, WipperSnapper automatically reads values from the sensor and sends them to Adafruit IO.

Going Further

Want to learn more about Adafruit IO WipperSnapper? We have more complex projects on the Adafruit Learning System.

This guide was first published on Dec 22, 2021. It was last updated on 2022-04-13 13:37:40 -0400.

This page (WipperSnapper Usage) was last updated on May 27, 2022.

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