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Edge triggered DMA losing first byte | Cypress Semiconductor

Edge triggered DMA losing first byte

Summary: 6 Replies, Latest post by Rocketmagnet on 10 Sep 2014 03:57 AM PDT
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Rocketmagnet's picture
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159 posts

 I want to create an SPI component which leaves a small gap between bytes. To achieve this, I am using edge triggered DMA to transfer bytes to the SPI component. A PWM component is used to create the edges. I can vary the PWM period to vary the inter-byte spacing.

 

It all works, except that the first byte is always missing! When I try to transfer the following bytes: {1,2,3,4,5,6,7,8} I see {2,3,4,5,6,7,8} come from the SPI component.

 

When I was using the usual level triggered DMA, I never saw this problem.  What am I doing wrong? Please see attached waveform.

 

Many thanks

Hugo

 

 

 

Rocketmagnet's picture
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159 posts

 And here's the workspace bundle:

 

 

Rocketmagnet's picture
User
159 posts

 Let's try again ...

Rocketmagnet's picture
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159 posts

 Argh! Why is this forum so bad? It won't let me post the workspace bundle.  I'll e-mail it to anyone who wants it.

Hugo

 

user_1377889's picture
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10803 posts

Keep calm, you're not the only one here gnawing nails about the &$§$&!! forum software.

Use internet explorer or firefox to post the zip-file.

 

Bob

Rocketmagnet's picture
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159 posts

OK, trying again with Firefox.

Rocketmagnet's picture
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159 posts

Unbelievable. Still doesn't work!  Hello Cypress? Can you fix this terrible forum please? Everyone else's forums are at least two generations ahead. Even open-source forum software is better than this joke.

 

We should all just move to http://electronics.stackexchange.com/

Or to http://area51.stackexchange.com/proposals/50195/embedded-systems when it comes back.

 

I've uploaded the file to my Google Drive: 103-000-2006-01.cywrk.Archive02.zip

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