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SPORT Communication between two DSPs using DMA

Question asked by tduong on Mar 10, 2010
Latest reply on Mar 12, 2010 by jeyanthi.jegadeesan

Hi,

 

I am trying to send data from one ADSP-21375 to another ADSP-21375. The scheme is as follows:

 

1. TX DSP turns TX-flag on and waits for reply.

2. RX DSP turns RX-flag on and waits.

3. TX DSP sends data, turns TX-flag off, and waits.

4. RX DSP sees TX-flag off, reads data, and turns RX-flag off. Exits.

5. TX DSP sees TX-flag off and Exits.

 

This works great in one direction. But when I implement the same thing but with the DSP switched, I run into a strange issue where the RX DSP hangs while waiting to finish reading. It somehow thinks there are only 2 words being sent instead of 8, and *pCSP1A stays at 6. Furthermore, the RX buffer shows the last 2 words from the TX DSP, but it's offset:

 

Like this:

 

0x77777778

0x88888880

 

Does anyone have any insight into this issue? I've attached the code.

 

Thanks!

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