How Do I Start Working with SMBus Devices?

Question from the Customer:

I need to program and monitor an SMBus device. Which Total Phase instruments could I use for this project?

Response from Technical Support:

Thanks for your question! The System Management Bus (SMBus) protocol is a derivative of the Inter-Integrated Circuit (I2C) protocol. Because of their similarities, our I2C host adapters and I2C protocol analyzer can be used with your SMBus project.

Comparing I2C and SMBus Protocols

I2C and SMBus are both 2-wire buses using a master and addressable slaves. SMBus is primarily used on PC motherboards and in embedded systems for monitoring critical parameters such as voltage supply, temperature, and fan control.

There are some differences about what these two protocols support and how they function. Both buses support a bitrate of 100 kHz, however I2C does support higher speeds so compatibility is only available below 100 kHz. Additionally, SMBus specifies a minimum clock speed and 35 ms timeout interval, while the I2C bus can hold the clock low as long as necessary.

For more information on these differences, you can take a look at these articles:

I2C Tools that Work with SMBus Devices

Here is a table so you can quickly compare the Total Phase devices that support I2C. (Note: the Cheetah SPI Host Adapter only supports the SPI protocol). The other tools can support both I2C (SMBus) and SPI protocols.

Compare the features of the Promira and the I2C/SPI Active Applications, and the Cheetah and Aardvark host adapters.

Following is a summary of the Total Phase devices that can support your project.

I2C and SMBus Host Adapters

We have two host adapters that are compatible with the SMBus.

Aardvark I2C/SPI Host Adapter

The Aardvark I2C Host Adapter is a fast and powerful bus host adapter that communicates with your computer via USB, and can function as a Master or a Slave. In addition to I2C and SMBus devices, this adapter also interfaces with SPI buses.

Promira Serial Platform

The Promira Serial Platform is an advanced platform that can communicate faster via Ethernet or USB, provides built-in level shifting, and more. The license options (purchased separately) support a range of protocols. For your project: I2C Active - Level 1 Application is recommended. The Promira platform can function as an I2C Master or I2C Slave.

I2C and SMBus Protocol Analyzer

The Beagle I2C/SPI Protocol Analyzer can be used to monitor and capture real-time I2C data. The Data Center Software offers SMBus decoding when using the Beagle I2C/SPI analyzer. To enable SMBus decoding, select the SMBus Decoding option in the I2C Configuration Manager dialog. For more details on how to decode SMBus transactions in the Data Center Software, please see the SMBus section 8.5.2 in the Data Center Software User Manual.

Other SMBus Tools

Test and Development

  • With its I2C Port Expander, the I2C/SPI Activity Board can be used to test and develop SMBus devices.
  • The I2C Development Kit includes the activity board as well as the Aardvark I2C/SPI Host Adapter, the Beagle I2C/SPI Protocol Analyzer, and cables. This is a powerful and cost-effective way to start a new project.

Software Applications

Using Our Tools with SMBus

In addition to the information in the user manuals, here are two examples of using our tools with the SMBus:

Additional resources that you may find helpful include the following:

We hope this answers your question. Looking for more information? You can contact us and request a demo that applies to your application, as well as ask about our Total Phase products.

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