OpenCores
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ACK not sent for all read bytes #38
Open xweing opened this issue over 6 years ago
xweing commented over 6 years ago

Hi Richard,

I am facing a problem where, during a sequential read of 6 bytes, the core automatically inserts the ACK-bit on the 9th bit for the first 4 bytes, then suddenly does not insert ACK-bit on the 5th byte.

This causes my SDA line to be held low, and arbitration-lost flag to be flagged high.. even though i had stopped my core.

1) Any idea why the core suddenly does not ACK the read-byte? My code is same for all the 6 bytes. 2) Any idea how to overcome this arbitration-lost flag?

Thanks & regards, Megan

rherveille commented over 6 years ago

Is the controller the only master on the bus? Something goes wrong with the communication. Seems like some other module is forcing SDA low, causing the arbitration lost.

rherveille was assigned over 6 years ago
xweing commented over 6 years ago

I am using only 1 master and 1 slave. There is no other ongoing module to force the SDA low...

xweing commented over 6 years ago

Hi Richard,

Now I zoomed in to the problem on the last byte read..

The master should clock on 8 SCL pulse (for the last byte read) + 1 SCL pulse for NACK. But what I am seeing is the wishbone core just clock out 8 SCL pulse and the SCL just stays high after that.

Any idea how to solve this problem?

rherveille commented over 6 years ago

That sounds wrong. Can you send me your testbench (or entire setup) in a private email. I will take a look.

Richard

xweing commented over 6 years ago

I've sent you an email at your opencores.org mail account.. do take a look.. thanks!


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