Products > Test Equipment
First picture on EEVblog of the new R&S MXO4 series oscilloscope :)
shabaz:
Hi,
I have tried *CS permanently low from the first byte to the last byte, and it makes no difference, it works for me. Please see the attached screenshot.
As mentioned, this is making use of the History feature, so I can page through the content, and the performance and decode is fast (I can take a video of it if required).
If I do not use the history feature, as mentioned further up, I do see performance struggle with about 100k bytes of the decode. With the history feature, I have not seen any issue with 600k bytes (that's the max I have tried in the past, although that was with RS-485. With SPI, I have just tested 256k).
If you have an example scenario that you can simulate with (say) a Raspberry Pi or Pi Pico, and a screenshot or video of what you see on your current setup, then anyone can try to set it up so that a precise comparison can be made if you like? Because otherwise, for all I know, unfortunately my SPI configuration or speed, or a dozen other things, may be completely different to what you used.
luudee:
--- Quote from: shabaz on July 14, 2023, 04:13:12 am ---Hi,
I have tried *CS permanently low from the first byte to the last byte, and it makes no difference, it works for me. Please see the attached screenshot.
As mentioned, this is making use of the History feature, so I can page through the content, and the performance and decode is fast (I can take a video of it if required).
If I do not use the history feature, as mentioned further up, I do see performance struggle with about 100k bytes of the decode. With the history feature, I have not seen any issue with 600k bytes (that's the max I have tried in the past, although that was with RS-485. With SPI, I have just tested 256k).
If you have an example scenario that you can simulate with (say) a Raspberry Pi or Pi Pico, and a screenshot or video of what you see on your current setup, then anyone can try to set it up so that a precise comparison can be made if you like? Because otherwise, for all I know, unfortunately my SPI configuration or speed, or a dozen other things, may be completely different to what you used.
--- End quote ---
Thank you for the test.
I don't know what to say. It does look like it is working for you. I wonder if I indeed had some very old
firmware, which is also odd, why would R&S give me a scope with useless FW ?!
In any case, my test case is a custom product I designed for a client., It has a CPU booting from SPI
FLASH. We were trying to see where it was stopping to read the SPI FLASH, hence huge capture, etc ...
At the end got it all working ...
One more thing, what's the speed of your SPI bus ? In my case, it was running at 20 MHz.
luudee
jusaca:
From the screenshot saying "Bitrate: 991600 kbps" I would assume the SPI clock to be set to 1 MHz ;)
shabaz:
Just out of curiosity I tried using the analog channels today, to see what difference there is, using a 20 MHz (approx.) SPI clock. It is in the file called spi-using-analog-channels.jpg. This example has 256,000 bytes of SPI data as before.
The MXO 4 allows the creation of additional views of the data (called layouts in R&S terminology), and the next screenshot shows the SPI SCK line on a separate view to blow it up to see more detail (sch-magnified-view.jpg).
What's neat is that it is possible to see any anomalies during the entire acquisition. In that example, a 100 pF load was deliberately applied to the SCK line part-way through the transfer, and it is possible to see the impact the load had on the analog signal as well as locating the data corruption (if the analog signal is significantly distorted).
It's easy to find the anomaly, by dragging the slider (see anomaly-located.jpg) until the visible waveform shows the corruption, and then the page of data has been identified.
The final attached image just shows a temperature-colored view to see how much consistency there was for the SCK signal over time.
nctnico:
I assume the MXO4 also has reverse brightness. This makes an anomaly stand out even better (at least on the RTM3004 it does).
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