Is there any way I can edit the CS of the SPI bus and reload back to the software for decoding?
I have a chip that communicates with an external device using the SPI bus (SDI,SDO, SCK and CSB1)
The same device also communicates with an integrated AFE using the same bus (SDI,SDO and SCK) but the CSB2 is not exposed. So the software captures the signals but doesn’t decode since CSB1 is high. If I can manipulate the CSB1 to low during the internal bus transactions, the software would think the SPI transactions were from the same device and decode ( i have to make sure which ones are belong to which device
Unfortunately the app doesn’t support editing the data (which would be awesome, but a huge project) however, you can turn off the enable channel in the SPI analyzer by clearing the selected channel. If you select “None” in the dropdown, the option will clear. Then it will act as if the enable channel is always active.
Btw you can have 2 or more instances of the SPI analyzer added at the same time, even using the same channels if that helps. I often do that when I have multiple devices on the same bus with different chip select signals.
Here is an example:
The first row of results are the normal SPI settings.
The second row is the same as the first, but with the enable line polarity swapped. This only decodes bytes when enable is high - that might be what you want.
Third, the enable channel is cleared, so it decodes all bytes.
Note, if you have the enable line off, and the capture starts in the middle of an SPI byte, the decoder won’t synchronize and all the bytes will be offset by a few bits. The simplest way to fix that is just trim the first partial SPI byte in the capture. (right-click on the graph and select delete data > before this point)