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21565 problems in audio application.

Category: Hardware
Product Number: ADSP-21565
Software Version: CCES 2.10.0


I use multi 21565s in my board, each 21565 exchange datas through SPORTs with others. One MCU control and update coefficients in 21565s using UART0.

My questions are below.

1. In datasheet, 21565 CLKIN0 is 1.8V input, however the other chips such as ADC,DAC in my board is 3.3V input. To sync all the chips I should use one on crystal. If I use 1.8V supply, how to get 3.3V clock. Or If I use 3.3V supply, how to get 1.8V clock.

2. This is a strange problem I met in two of all 21565s in my board. I don't know it is hardware or software problem. In 21565 I use UART0 to receive coefficients, It seems that when the UART0 interrupt occur, the datas of one SPORT will be disturbed, but the other SPORTs is normal. If I exchange the DAI pins of the troubled SPORT and the normal SPORT,  then the problem will change to the new DAI pins of troubled SPORT. So the problem maybe come from the SPORT. 

    Both the 2 chips which have this problem, if I close the UART0, the problem disappeared. One chip I change the UART0 init affer SPORTs init, then the problem is solved. The other chip I can't solve this problem anyway besides close UART0. If I disconnect the UART0 pins outside,  the problem disappeared too.

    Wish you can give me some directions what maybe cause this problem.


  • Hi,

    The ADSP-2156X processor SYS_CLKIN power domain is 1.8V. We suggest you use programmable clock generator with different power domain supported chip, otherwise you have to use separate crystal for processor.

    For your other issue, we suggest you change the interrupt priority level and check how SPORT and UART will behave.

    Anand Selvaraj.

  • Hi,

    Like si5356 in the EZKIT board? It's a good idea.

    I forgot to say I tried to change the priority before and it can't help.

    However I solve it by using another group of clk and fs rather than generate by itself. Although it's good now, I have not found the really problem, so it may be not safety enough. I am not sure if it will trouble later.

    Besides, I have another question about SPDIF.

    If I don't enable standalone mode, the SPDIF tx will not send datas out, how can I send datas without using standalone mode?

    In standalone mode, the output data is correct most time, however sometimes it will be clicked, I have not found how to solve it. I will go on.


  • Hi,

    We understand that your query is already handled in below thread. To avoid duplication of effort please continue the discussion there.

    Anand Selvaraj.