Support Question of the Week: How Can I Use the Beagle I2C/SPI Protocol Analyzer to Capture Data from Multiple SPI Slaves on an SPI Bus?

 

I have the BeagleTM I2C/SPI Protocol Analyzer, and I need to capture any glitches that may occur on an SPI bus where multiple SPI slaves are attached. How can I capture data from multiple SPI Slaves that are synchronized on an SPI bus?

Thank you for your question! Multiple SPI Slave device signals can be captured by using both the Cheetah TM SPI Host Adapter and the Beagle I2C/SPI Protocol Analyzer. The BeagleI2C/SPI analyzer supports one SPI slave select (SS) signal; the Cheetah adapter supports three SPI SS signals. Following are two examples use these devices to capture data from multiple SPI slave devices.

 

Example of connecting multiple SPI slaves to one SPI master. Figure 1: Cheetah SPI Host Adapter Supports Multiple SPI Slave Signals

 

To identify each signal from each SPI slave device, you can use a Beagle I2C/SPI analyzer for each device. The following example captures two SPI slave device signals on the SPI device. This setup uses one Cheetah host adapter, two Beagle I2C/SPI protocol analyzers, and two instances of the Data CenterTM Software.

  1. Connect each Beagle I2C/SPI analyzer (Beagle 1 and Beagle 2) to two separate SS signals.
  2. Connect Beagle 1 to a Cheetah SS signal.
  3. Connect Beagle 2 to another Cheetah SS signal.
  4. Connect one instance of the Data Center Software to Beagle 1.
  5. Connect another instance of the Data Center Software to Beagle 2.

If you do not need to identify the behavior from each SPI slave device, you can multiplex the SS signals and use fewer devices. The following example captures two SPI slave device signals on the SPI bus. This setup uses one Cheetah Adapter, one Beagle I2C/SPI analyzers, one 2-to-1 multiplexer (mux) and one instance of the Data Center Software.

  1. Connect the multiplexer to two SPI device slaves and the Cheetah SS signal.
  2. Connect the Cheetah to the Beagle I2C/SPI SS signal.
  3. Connect the Data Center Software to the Beagle I2C/SPI analyzer. Note - As both signals will be displayed in one Data Center Software window, the signal source, captured from which Cheetah adapter, will not be identified.

For more information, please refer to the following documents:

We hope this answers your question. If you have other questions about our protocol analyzers, software or other Total Phase products, feel free to email us at sales@totalphase.com or submit a request for technical support.

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