Products > Test Equipment
Siglent SDS1000X-HD - Bugs and "features" thread.
skander36:
--- Quote from: BreakingOhmsLaw on April 06, 2024, 06:20:44 pm ---I was playing arround with the Bode Plot function and FFT. Then I shut down the unit and went for lunch.
When I returned, it immediately started up in that state.
When this fault is active, it looks like it ia trying to interpolate anything into a 250MHz sine wave. It also combines all the samples from all channels into one trace. Really looks like the entire acquisition goes bonkers.
--- End quote ---
Bode plot was also responsible for PSRR bug. It was not closing completely and lock the scope when Power Analysis menu were open. The scope must be forced shutdown, reset to factory, and sometimes secure erased in order to be recovered.
BreakingOhmsLaw:
So, I have a theory of what's happening with the I²C bug:
A CAN bus expects something called "bit stuffing" if you try and transmit five or more bits that are all ones or zeroes. So instead of the 5th identical bit, an inverted "stuff bit" gets inserted. This is because CAN has no clock signal, so CAN relies on the data bits themselves to recover a clock signal. Hence, bit stuffing ensures that you have an edge every now and then to synchronize on.
Let's look at that bug again. Only addresses starting with "11110" are not decoded. I'm willing to wager a nice bottle of single malt, that I²C decoding shares code with the CAN decoder and tosses out the "0" as a supposed "stuff bit". Consequently, the I²2 frame is "missing "a bit and is not decoded because it seems incomplete.
I²C has a clock signal, so bit stuffing is not required. But somehow "11110" gets treated the way a CAN frame would. By the way, "00001" works fine.
What do you think?
skander36:
It is possible but as long as you don't have a confirmation from inside, you can't be sure about the cause.
For me as long as it can decode reliably what I need is enough for time being ...
2N3055:
--- Quote from: BreakingOhmsLaw on April 06, 2024, 09:13:30 pm ---So, I have a theory of what's happening with the I²C bug:
A CAN bus expects something called "bit stuffing" if you try and transmit five or more bits that are all ones or zeroes. So instead of the 5th identical bit, an inverted "stuff bit" gets inserted. This is because CAN has no clock signal, so CAN relies on the data bits themselves to recover a clock signal. Hence, bit stuffing ensures that you have an edge every now and then to synchronize on.
Let's look at that bug again. Only addresses starting with "11110" are not decoded. I'm willing to wager a nice bottle of single malt, that I²C decoding shares code with the CAN decoder and tosses out the "0" as a supposed "stuff bit". Consequently, the I²2 frame is "missing "a bit and is not decoded because it seems incomplete.
I²C has a clock signal, so bit stuffing is not required. But somehow "11110" gets treated the way a CAN frame would. By the way, "00001" works fine.
What do you think?
--- End quote ---
I'll send you my address for the bottle. I trust you to pick something nice.
It doesn't work because those are not valid packets. From standard:
111 10XX X 10-bit slave addressing
111 11XX X Reserved for future purposes
Nice page:
https://www.totalphase.com/support/articles/200349176-7-bit-8-bit-and-10-bit-i2c-slave-addressing/
And if your reference for this is Keysight scope make note that their implementation is not correct, i.e. not according to standard. It will decode 7bit addresses with invalid ranges.
Picoscope correctly decodes both 7 and 10 bit addressed I2C
BreakingOhmsLaw:
--- Quote from: 2N3055 on April 06, 2024, 10:53:56 pm ---I'll send you my address for the bottle. I trust you to pick something nice.
--- End quote ---
Please do, I am a man of my word.
--- Quote ---And if your reference for this is Keysight scope make note that their implementation is not correct[...]
--- End quote ---
Indeed. Come to think of it, I don't think I've ever used a non 7-bit I²C part in anger in the past 32 years as an EE. I completely forgot about the extended addressing.
Anyway, a fine bottle of scotch will find it's way to Croatia as soon as it knows where to go. :-+
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version