Linux/AM5728: McASP data issue

michael.ye

Prodigy 60 points

Part Number: AM5728

Tool/software: Linux

hi:Biser Gatchev-XID

can you give me a help.

hardware: AM5728

software: Linux version 4.4.19-g6c9d0b5-dirty (root@ubuntu) (gcc version 5.3.1 20160113 (Linaro GCC 5.3-2016.02) ) #121 SMP PREEMPT Mon Apr 10 00:02:07 CST 2017

procedure:

1、 followed the guide and step by step for interfacing an audio DAC to the McASP on AM728 devices (Sitara Linux Software Developer's Guide → Sitara Linux SDK → Audio: DAC Example processors.wiki.ti.com/index.php )

2、use the alsa-lib/test/pcm_min to transmit some data. following is some data i want to transmit.(figure 1)

3、then use the LA5061 Logic Analyzer to catch the output, as the following:

when I use omapconf dump mcasp1 when running, the reg. value is:

and my issue is:

why input 0xFFFF and the output is 0xFFFE?

over 8 years ago

0 michael.ye over 8 years ago

Prodigy 60 points

this figure can see more clk and data info than figure 1:

why the ouput like this at channel6? Another way of saying why the output data are not: 0xFFFF,0xFFFF,0xFFFF,0xFFFF,0x0001,0x0001....

0 Biser Gatchev-XID over 8 years ago in reply to michael.ye

TI__Guru**** 393215 points

The software team have been notified. They will respond here.

0 michael.ye over 8 years ago in reply to Biser Gatchev-XID

Prodigy 60 points

Thanks a lot. Biser Gatchev-XID.

and today i found another phenomenon：
when I transmit -528 and -259 are the same output . that is : -1056
so how does mcasp1 work to make the output data?

0 michael.ye over 8 years ago in reply to Biser Gatchev-XID

Prodigy 60 points

hi Biser Gatchev-XID ,

Is there any progress on this issue？

thanks...

0 Yordan Kovachev over 8 years ago in reply to michael.ye

TI__Guru**** 161600 points

Hi,

Sorry for the delay.

Can you get a file to play, using aplay or gst commands? Do you get any errors on the console when transmitting 0xFFFF

Best Regards,
Yordan

0 michael.ye over 8 years ago in reply to Yordan Kovachev

Prodigy 60 points

hi,Yordan Kovachev

no errors on th console when transmitting 0xFFFF...

Can you test it yourself in your board and tell me your result..

thank you for your help...

0 michael.ye over 8 years ago in reply to Yordan Kovachev

Prodigy 60 points

Hi Yordan Kovachev thanks for your hints.

I use aplay to transmits a wav file. within 0xFFFF. and the result is as expect.

But what are the differences between the two methods? (aplay and pcm_min)

i think is not the driver problem. maybe is the alsalib....

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Linux/AM5728: McASP data issue