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SPI Decoding Failing

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SPI Decoding Failing

Postby Frustrated » Tue Apr 22, 2014 7:37 pm

20140422-0002.png
Hi,

Let me start by saying that I really trying to make this scope work. I'm frustrated because these seem to have so much potential. Things that lack potential and suck do not frustrate me :)

I'm accustomed to using middle-end $7K-$12K Tek and Agilent scopes to bring-up and debug 32-bit ARM embedded systems and have always purchased MSOs. Tek/Agilent really stick it to you when it comes the cost of serial decoding so when I saw that you get it for free with the Picoscope it made me happy. However, I'm finding that I cannot depend on the decoding or the digital waveforms.

So two issues:

In the attached image how is the first byte unknown? I have carefully specified the chip select and the rising clock edge. How can it not decode this?

What is going on with the chip select? I've selected TTL for the digital channels which has a threshold of 1.5V but the crosstalk is not near that value. If the decoder is seeing this as actual chip select fluctuations then I can see why it is confused.

Thanks,

Kenny

PicoScope® 6 - PC Oscilloscope software version: 6.8.10.13
Model: PicoScope 3205MSO
Serial Number: CY050/103
USB Version: 2.0
Calibration Date: Thursday, June 06, 2013
Hardware Version: 1
Driver Version: 1.3.0.127
Firmware Version: 1.3.3.0 / 0.6.12.0
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Re: SPI Decoding Failing

Postby Martyn » Wed Apr 23, 2014 8:06 am

Please can you post a psdata file, we can then look at the settings to help diagnose the issue.

To do this select File->Save and then select "current waveform only" to reduce the size of the file produced.
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