Original Photo by Visual Tag Mx

I am using an Aardvark I2C/SPI Host Adapter that will be connected to the SMBus of a power monitor that is embedded in a circuit board. Here is the planned setup:

• The address of the slave is 0x4C (7-bit)
• The SCL and SDL signals of the Aardvark adapter will be connected to the respective slaves SCL and SDA of the power monitor.

My questions:

• How should I read and write with the Aardvark adapter through the SMBus?
• Is there a way I can test the setup before working on the actual system? I don’t yet have the power monitor.

Thanks for your questions! We have an example that can help you start your project. For prototyping, we suggest using the I2C/SPI Activity Board  with Control Center Serial Software to emulate SMBus interactions. As the SMBus is a derivative of the I2C bus protocols, the Aardvark adapter has been successfully used with SMBus devices by many customers.

Example of Communicating with SMBus

Here is an example of communicating with an SMBus device. In this example, the packet is structured as follows:

• The slave 7-bit address is 0x50
• The command code is 0x40
• The purpose is reading out 1 byte of data

Here are the parameters that were applied with the Control Center Serial Software:

1. In slave address enter 0x50
2. In the message window input 40
3. Check no stop
4. In Number of Bytes enter 1
5. Click Master Write
6. Click Master Read

Using the I2C/SPI Activity Board to Prototype and Pre-Test

The image of the Control Center Serial Software GUI below shows the results of using an Aardvark adapter as the master device and the I2C/SPI Activity Board as the slave device.

The I2C/SPI Activity Board provides known-working I2C and SPI slave devices, which makes it an effective resource for testing and debugging as it helps differentiate between hardware and software bugs and is a baseline for software usage. The target devices on the activity board are also a means for new developers and verification engineers to learn the mechanics of the I2C and SPI bus protocols. Here is a summary of what this activity board provides:

• I2C Port Expander with configurable I2C address and a full complement of LEDs
• I2C EEPROM with configurable I2C address
• SPI EEPROM with jumpered Slave Select

For monitoring and analyzing traffic, you can use the Beagle I2C/SPI Protocol Analyzer. For more information, refer to the article about monitoring and decoding SMBus data.

We hope this answers your questions. Additional resources that you may find helpful include the following:

• Aardvark I2C/SPI Host Adapter User Manual
• I2C/SPI Activity Board User Manual
• Control Center Serial Software User Manual
• Beagle Protocol Analyzer User Manual
• I2C Background
• Differences between I2C and SMBus

If you want more information, feel free to contact us with your questions, or request a demo that applies to your application.