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Requirements to decode SPI

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Requirements to decode SPI

Postby drnicolas » Sun Feb 17, 2013 6:47 am

I have porblems to decode SPI-data.

I have D0,D1,D2 for MISO, SCK and CS. I have automatic triggering on falling edge of D2.
Settings are made for 16 Bit.

But, I normally see no decoded data (unknown only)

My 16-Bits come in 2 Bytes with a short gap between them.

WHat can I do to safely decode SPI ?
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Re: Requirements to decode SPI

Postby Martyn » Mon Feb 18, 2013 7:57 am

Can you post a psdata file, File->SaveCurrentWaveformAs, so that we can look at the data and the decode settings
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Re: Requirements to decode SPI

Postby drnicolas » Wed Feb 20, 2013 3:01 pm

I am a little better now, but not yet satisfied.

I actually don't know, how I managed that at least some of the packets are decoded.

Maybe the small spikes seen in the data are the problem. Can I get rid of them ?
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Re: Requirements to decode SPI

Postby drnicolas » Sat Feb 23, 2013 4:39 pm

Okay, here comes a psdata-file.

It comes from a 12-bit SPI (not 16 Bit).

I always get <unknown> instead of useful data.

D5 is the return-channel and therefore has no useful data at the momemnt.

Do you have any tips for me ?
Attachments
12-Bit-SPI.psdata
(18.4 KiB) Downloaded 121 times
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Re: Requirements to decode SPI

Postby Martyn » Mon Feb 25, 2013 3:55 pm

Unfortunately we only have 8,16,24 or 32 bit decoding at present and none of these will decode the 12bit signals you have. The closest is 8 bit which gets the first two nibbles of the data but not the third.
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Re: Requirements to decode SPI

Postby drnicolas » Mon Feb 25, 2013 4:14 pm

But, I have also lots of problems with 32-Bits.

Otherwise, I can write any number of bits in the decoding settings - indeed, 8,16,32 are given in the drop-down list. But I can write any number I like.
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Re: Requirements to decode SPI

Postby Martyn » Mon Feb 25, 2013 4:25 pm

I didn't know that worked, they keep adding features without telling us :(

If you change the clock sampling to falling edge, having manually entered 12 bits, you can decode 082 for MSB or 410 for LSB. Are either of these correct ?
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