mangOH Red Digital Outputs

Now that you've decided to connect to your mangOH Red via GPIO, you'll need to:

1. Plug the antennas into the mangOH Red.
2. Plug the LCD screen onto the mangOH Red's Raspberry Pi connector, ensuring that the connector is aligned to the left.
3. Ensure that dip switches 1, 3, 8 are configured to ON.
4. Take a look at the GPIO pin map and decide which GPIO pin you'll use.
5. Configure the pin for digital output for via the GPIO Service screen in Octave.

You can then perform the steps in the following tutorials to verify that the pin is working correctly as a digital output and to control it via Octave:

• Tutorial 1: Verifying the Pin Voltage with a Multimeter
• Tutorial 2: Using an LED to Verify that the pin Voltage can be Toggled via Octave

Configuring a Digit Output

Follow the steps below to configure a digital output pin:

1. Navigate to Device > Services, locate the GPIO section, and click Configure.
2. Locate the Add pin section.
3. Click the Pin drop down and select a GPIO pin (e.g. WP_GPIO_2). Note the expected voltage indicated for the pin which will be either 1800mV or 3300mV.
4. (Optional) Change the name in Resource to a more descriptive name.
5. Set the Direction to Output.
6. Click Add. The configured output pin appears in the list of GPIO Services.

Tutorial 1: Verifying the Pin Voltage with a Multimeter

In this tutorial, you will enable the voltage on the mangOH Red GPIO pin and use a multimeter to verify that the pin is asserting the expected voltage.

📘

Note

For this tutorial you will need a multimeter.

Follow the steps below to set the value for the digital output pin:

1. Ensure you have completed the steps above in Configuring a Digit Output.
2. Navigate to Device > Resources.
3. Locate and expand io.
4. Locate the Resource corresponding to the output pin configured in the previous section. The name will be postfixed with /value (e.g. WP_GPIO_2/value).
5. Click on the Configured value column and set the value to true or false.

The GPIO pin should now be producing a voltage of either 3300mV or 1800mV.

Testing the Output

Follow the steps below to verify that the GPIO pin is outputting the correct voltage:

1. Configure your multimeter to measure voltage levels up to 3.3 VDC.
2. Place the ground probe of the multimeter onto a GPIO ground pin (e.g. Pin 25).
3. Place the positive probe of the multimeter onto the GPIO output pin configured in the previous sections.
4. Verify that the voltage from the GPIO pin matches that defined for the resource (3.3V or 1.8V).

Tutorial 2: Using an LED to Verify that the pin Voltage can be Toggled via Octave

In this tutorial you will wire up an LED to a GPIO pin on the mangOH Red, enable the pin in Octave, and verify that the pin can be controlled via Octave.

📘

Note

For this tutorial you will need:

• A LED.
• A pair of jumper wires to wire the LED to the RPi pins of the mangOH Red.
• (Optional) A breadboard to make the connections on.

Wire up the LED

1. Connect a jumper wire between pin 1 (3.3V) on the RPi connector to the positive lead of the LED.
2. Connect another jumper wire between your selected GPIO pin (e.g. pin 7 (WP_GPIO_3)) to the negative lead of the LED.

Enabling and Verifying the Output Voltage

Follow the steps below to set the value for the digital output pin:

1. Ensure you have completed the steps above in Configuring a Digit Output.
2. Navigate to Device > Resources.
3. Locate and expand io.
4. Locate the resource corresponding to the output pin configured in the previous section. The name will be postfixed with /value (e.g. WP_GPIO_3/value).
5. Click on the Configured value column and set the value to true or false.

After a few seconds, the LED should light up. This indicates that the voltage on the GPIO pin can be set successfully via Octave and demonstrates how Octave, in conjunction with GPIO pins on an mangOH Red can be used to control an external device.