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Rigol DHO814 - capturing CAN frames
eTobey:
--- Quote from: nctnico on March 20, 2024, 06:50:55 pm --- Very annoying if you want to relate packets to eachother.
--- End quote ---
With the Rigol, you can see (and read) only one frame at once completely, and thats it. With the signlent its like hundrets? Thats quite an advantage there!
bobxyz:
I've been playing around with I2C decoding and I think it should be similar to CANbus. Here's what I do:
First, set the scope mode so that pressing the horizontal timescale knob switches to Zoom mode (instead of fine adjust). Settings -> Utility -> Setup : Fine/Zoom=Zoom
Next, setup Settings -> Decode : I2C, and turn on Bus Status
Now, hit run and adjust the horizontal time base to capture as much as possible while still seeing something in the decoded protocol area. Note: if you go slower than 20ms/div (i.e. scrolling display), protocol decode is disabled and you'll need to go back to the previous step to turn Bus Status back on. Hit the stop button when you have a reasonable capture. In my case, I have two I2C bursts over 100ms (the code is running 10x per second I2C polling rate).
Press the horizontal time scale knob to switch into Zoom mode, then use the horizontal position knob and the time scale knob to display a burst of I2C activity
To view the earlier I2C burst (on the left of the capture), zoom back out using the time scale knob, then using the touchscreen, drag your finger on the zoomed display to shift it back to the first I2C burst. Zoom in and drag as needed to view the earlier I2C burst
Let me know if this isn't clear enough, and more importantly, does this work for CANbus too?
-Bob
eTobey:
--- Quote from: bobxyz on March 21, 2024, 01:50:48 am ---Let me know if this isn't clear enough, and more importantly, does this work for CANbus too?
--- End quote ---
I dont know, because I joined the dark side of the force already (i already sent it back).
bobxyz:
I went ahead and tried CAN bus decoding with a DHO814 (v1.02 firmware) and it works about the same as I2C -- you need to do a big capture then zoom in (split screen) to see the decoded values.
One bug I ran across is that the CAN decode doesn't work when using a 10x probe (with a 10x scope setting). It works with a 1x probe. It also works with a 10x probe when the scope is left on 1x and voltage levels adjusted to 1/10th (~0.3v CAN threshold). The CAN triggering, versus the decode display, seems to work fine for both 1x and 10x.
The screen gets rather cluttered when displaying the decode list and zoomed waveforms together.
Note: CAN decode/triggering on the DHO800 series seems to have been added in January with the later firmware updates - it wasn't supported originally, but is supported now, and is included in the newer datasheet/user manual. LIN bus is not [yet?] supported.
P.S. How are the cookies?
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