Cyclone V - major transceiver misunderstanding

Hi,

I think I really have an alignment problem and I don't know how to solve this. Here are the steps I did and the results I got:

I send an idle sequence from my custom component to the TX streaming interface of the xcvr custom phy. I monitor that in signal tap and see that I do not receive anything on the rx side which is fine because I have not connected an external data source, yet.

The next thing I do is to switch the serial loopback of the transceiver channel on. The result is that I now see my idle pattern at the streaming output of the xcvr custom phy. Because my idle pattern is 0x55555555, everything looks really good.

Now, as soon as I send data e.g. a sequence of 0xffffffff words, I can see that this sequence goes to the tx port of the xcvr custom phy and a moment later, I receive "something" on the loopback rx path. This something is almost my 0xffffffff pattern but it is shifted one symbol (8bit) and so the first 0xffffffff sequence I should receive instead has a symbol of my idle or preamble sequenece in it.

After my data block is completely transmitted, I again have one symbol shift in my data stream because the idle data also suffers from the above mentioned problem.

I suppose that this effect is caused due to a not functioning word alignment.

I have set up the word alignment in my custom xcvr phy just as in the transceiver toolkit example (pattern length 20; pattern "11111001111111111010"). And I believe that the transceiver toolkit example also uses an "FPGA fabric transceiver interface Width" of 40, just as my design.

I read in the documentation that I have to set the rx_enapatternalign flag to 1 in order to get the word alignment working. I did that but it has no effect on the word alignment.

I suppose that the xcvr core somehow "knows" that the rx data is not correct because I do not get an asi_valid flag. But, since I have this idle pattern running all the time, when I do not transmit my user block data, I was hoping that this is enough time to a) perform clock recovery and b) perform word alignment when the rx_enapatternalign flag is set.

But unfortunatley, it is not working as I intend it to do.

I attached a screenshot of a signal tap trace. It shows the idle pattern, my preamble pattern (0xaaaaaaaa) and the aformentioned user data block (0xffffffff). Finally, the idle pattern is transmitted, again.

The red arrows mark where the errors occurs due to the missing word alignment. The exclamation mark value shows that the user data block still contains a symbol from the preamble block. The blue arrors show, that those basic patterns are generally transferred in a plausible manner.

Just one remark. I always say, I use the patterns 0x55555555, 0xaaaaaaaa and 0xffffffff, but they look so different on the aso_data and asi_data signals. That is because I used the 32bit to 40bit scheme I described in the first post of this thread. Maybe somebody can tell me, if it is correct to do it that way, or if I misunderstood the description of the xcvr custom phy tx_data and rx_data description in the according Altera documentation.

Thanks,

Maik