| Products > Test Equipment |
| Gw Instek GDS2204E (200MHz 4 channel DSO) review |
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| nctnico:
--- Quote from: tautech on December 24, 2017, 09:14:01 pm --- --- Quote from: CC555 on December 24, 2017, 05:58:23 pm ---I don't know if my settings are 100% right but I would say this oscilloscope has a problem decoding serial buses with the memory and sample rates selected. --- End quote --- What would concern me more is the displayed signal integrity ? Not so much the scopes ability to portray it but the glitches and the variances in the data idle voltage of ~1/2/div. :-// Something's maybe not right with your digital circuit or probing technique. Jump back out of Decode and see what waveform shapes and amplitude you get then. --- End quote --- The shape of the signals isn't related to decoding. There are probably resistors between the various I2Cs devices to prevent one part of a circuit blowing up the rest of the circuit (safety barrier). Alternatively the value of the pull-up resistors may be too low so some devices may not sink enough current to pull the I2C lines completely low. Either way I've seen similar I2C signals before. |
| tautech:
--- Quote from: nctnico on December 25, 2017, 12:23:53 am --- --- Quote from: tautech on December 24, 2017, 09:14:01 pm --- --- Quote from: CC555 on December 24, 2017, 05:58:23 pm ---I don't know if my settings are 100% right but I would say this oscilloscope has a problem decoding serial buses with the memory and sample rates selected. --- End quote --- What would concern me more is the displayed signal integrity ? Not so much the scopes ability to portray it but the glitches and the variances in the data idle voltage of ~1/2/div. :-// Something's maybe not right with your digital circuit or probing technique. Jump back out of Decode and see what waveform shapes and amplitude you get then. --- End quote --- The shape of the signals isn't related to decoding. --- End quote --- If thresholds are set correctly. Runts like in the middle of this screenshot will throw a cat amongst the pigeons. |
| CC555:
Hello tautech, thx for you reply. I would say those spikes are not important, i2c communication is working properly in my device. It is a 100 khz clock so I think there is not any signal integrity problem (i didn't measure its rise time), the frequency is too low. In the end, I am not going to send the oscilloscope back, in the 1000 € range I think is a good choice. |
| CC555:
--- Quote from: nctnico on December 24, 2017, 05:42:46 pm ---I have not heard back from GW Instek's technical support in the EU but I'm pretty sure they are closed for the holidays. --- End quote --- Hello, any news from GW Instek? |
| nctnico:
--- Quote from: CC555 on January 09, 2018, 09:31:04 am --- --- Quote from: nctnico on December 24, 2017, 05:42:46 pm ---I have not heard back from GW Instek's technical support in the EU but I'm pretty sure they are closed for the holidays. --- End quote --- Hello, any news from GW Instek? --- End quote --- I got a reply saying they are working on it. I have not checked if a new firmware version has been released. |
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