I am working on a system that requires a slave device to have an I2C Interrupt Request output pin (nIRQ). When the I2C slave needs service, it alerts the I2C master by pulling the interrupt request low. I am looking at using the Aardvark I2C/SPI Host Adapter as the slave device and have questions about using the host adapter to generate the interrupt request signal.
- When the Aardvark adapter is in I2C mode and used as the host interface, are the unused SPI pins available as GPIO for toggling the interrupt request signal?
- Can the I2C mode and the GPIO mode be used simultaneously? I2C mode would be for configuring a slave register, and GPIO mode for viewing the interrupt line and generating the interrupt request.
Thank you for your questions! The Aardvark adapter can be used for your project exactly as needed. When the Aardvark adapter is in I2C mode, the unused pins in that mode can be used as GPIO. The same feature applies for the SPI mode – unused pins are available as GPIO. To help you get started, we will discuss using the GPIO features and provide references for more information.
Generating and Monitoring Interrupt Requests
We have two software applications for controlling the I2C and GPIO pins: Aardvark Software API and Control Center Serial Software. We have a Knowledge Base article that describes Using the Aardvark I2C/SPI Host Adapter GPIO Feature to Support Interrupts. This article includes an example of using the Aardvark Software API, which supports several programming languages and operating systems.
- For more information about API functions, refer to section 5 API Documentation of the Aardvark Adapter User Manual.
- For details about the host adapter signal pins, including which pins would be available in I2C mode, refer to section 2 Hardware Specifications of the Aardvark Adapter User Manual.
The next section is an introduction to using Control Center Serial Software.
Using GPIO Features
Control Center Serial Software can also enable the Aardvark I2C/SPI Host Adapter’s GPIO functionalities. The application is easy to use – all features of the Aardvark adapter are accessible with the GUI, including viewing the results. Here is an introduction to setting up and using this application.
- Install the Control Center Serial Software.
- Make sure the Aardvark adapter is not connected to your target system. Plug the Aardvark adapter into the computer and open the Control Center Serial Software.
- Using the Control Center Serial Software GUI, connect to the Aardvark adapter and select the GPIO only mode. Ensure that the I2C Pull-ups are disabled in the Aardvark menu.
- Set all the directions to OUT, and set all the outputs to logical 0. Using a meter, verify that all the pins output 0V.
- Set all the outputs to logical 1, and verify that the pin outputs are 3.3V.
- Perform similar tests with the input pins, such as in sending a 3.3V or 0V signal to each input, and then verify if the Aardvark adapter sees the signals correctly.
We hope this answers your questions. Additional resources that you may find helpful include the following:
If you want more information, feel free to contact us with your questions, or request a demo that applies to your application.