Logic Analyzer Log and Threshold mod for SVID protocol

[vicvicvar]

Dear forum 

I'm trying to log the activity on the I2C bus using my Analog Discovery 2 and the Logic Analyzer tool. I remember someone posted a script that will let you log all of the data. Can someone refer me to that post? 

Also, the specific protocol that I'm trying to decode is SVID (Serial voltage ID, Intel) that is based on I2C but with lower voltage threshold (0 to ~1V). I cannot find the option to change the threshold in Logic Analyzer. Within a script, could this be achieved? 

Thanks ! 

[attila]

Hello,

In WaveForms 2015 under Setting/Device select the 5th configuration to have input logic threshold at ~0.6V. The digital output high voltage remains 3.3V !
https://reference.digilentinc.com/waveforms3

The Logic Analyzer Logging tool lets you export the data, events or writing custom logging script.
The red T (in I2C row) opens protocol specific trigger wizard.
You can also Record at up to 1-2MHz up to 1-10M samples.

[vicvicvar]

Thanks !  It worked

 

[vicvicvar]

Is it also possible to send a I2C trace through the Analog Discovery? 

[attila]

Hello,

The custom pattern generator channel can be used to create I2C transmission. 
The script can be used to serialize the data, to generate custom pattern. See the attached project.

ScriptI2C.dwf3work

[vicvicvar]

Thanks attila, the more that I use the tool, the more i love it ! It will be useful to add USB protocol analyzer in the future!

I'm having a trouble that I cannot see any output when I hit the Run button under the script Tab. My scope is under SDA but I cannot trigger to any signal. 

Two questions:

• Is hitting the Run button on the script tab enough for sending a trace?
• What voltage should I expect? 3.3 or 5V ? 

Again thanks ! 

[attila]

Pressing the Run button in Script tool will execute the script. You can see the print (called from beginning of i2cwrite/read functions) in the output dock.
You can modify the I2C address and sent data in the last i2cwrite function arguments, and the i2cread address and number of bytes to read.

On Analog Discover (1&2) the digital output high voltage is 3.3V
In this project the output is configured for open drain and it needs external I2C pullups.

Use the Logic analyzer to see the I2C transmission. This is configured to trigger on I2C start condition in the project.