Support Question of the Week: Which Host Adapters Can I use to Communicate to One I2C Slave Device and Three SPI Slave Devices Simultaneously?

We have decided to use the AardvarkTM I2C/SPI Host Adapter for the purpose of I2C and SPI communication with our device under test (DUT). The scope is set up to act as a slave in I2C communication and interact with the device. At the same time, the adapter also have to act as a master to control three slaves in SPI communication. Our questions:

  • Is this approach possible with a single Aardvark Host Adapter?
  • Can the adapter act as a slave for I2C and a Master (of three slaves) in SPI communication at the same time?

Thanks for your questions! The Aardvark adapter is able to act as an I2C slave and as an SPI master at the same time. However, it has only one slave select line for SPI - it may be difficult to communicate with three different SPI devices on the same SPI bus. section 1.2.2 of the Aardvark Adapter User Manual (or section 1.1.2 of the Cheetah Adapter User Manual) describes how SPI operates, and shows an example of one SPI master controlling three slave devices with separate Slave Select (SS) signals.


Example of connecting multiple SPI slaves to one SPI master. Figure 1: Example of Multiple SPI Slaves


We recommend using the Aardvark adapter for the I2C communication and adding a Cheetah SPI Host Adapter for the SPI communication. The Cheetah adapter is a dedicated high-speed SPI master with three slave select lines, and supports the setup shown above in Figure 1. This implementation should meet your system requirements. For additional information about SPI Modes, and how the SPI master and the SPI slaves exchange information, please refer to section 1.1.3 of the Cheetah Adapter User Manual. For information about I2C master and slave communication, please refer to section 1.1 of the Aardvark Adapter User Manual.

For additional information about the Aardvark and Cheetah host adapters and other Total Phase products, please refer to the following documents:

Cheetah SPI Host Adapter Quick Start Guide
Cheetah Host Adapter User Manual
Aardvark I2C/SPI Host Adapter Quick Start GuideAardvark Host Adapter User ManualTotal Phase Products
Product Selector Guide

We hope this answers your question. If you have other questions about our host adapters or other Total Phase products, feel free to email us at or submit a request for technical support.

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