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spi controller

Former Member

I am trying to configure the SPI controller on board the ARM processor of zedboard. I am closely following the instructions given in UG585. I have 2 questions which I am not able to solve.

(1) The user guide stats that Tx-FIFO is 128 bytes long but how to access that FIFO. I see that there is only one Tx_data_reg0 which can contain only one byte of valid data.

(2) Assuming that I write a byte of data into Tx_data_reg0, I see that it is appearing on the MISO line contentiously even after slave select is de-asserted and SPI controller is disabled, how would I stop data transfer after that one byte.
(SS is going high but data and clock do not stop even after disabling SPI controller).

Could someone please help me sorting out these issues.

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  • 0

    Hello Harsha,

     

    I would suggest starting with the documentation, examples, and source code provided with the SDK. You can access this material either using the links in the system.mss file in the SDK or directly from the SDK installation files. The typical location for a 2015.2 installation is:

     

    C:\Xilinx\SDK\2015.2\data\embeddedsw\XilinxProcessorIPLib\drivers\spips_v3_0

     

    If any of the forum users have answers to your specific questions please post. You may also want to take a look at the Xilinx Community forums as well as this question is not specific to the ZedBoard:

     

    https://forums.xilinx.com/

     

    -Gary

  • 0 in reply to Former Member

    Yes I did look at the example code given in the SDK and also I did study the documentation. The problem is quite simple. I am trying to send data with manual start enabled. writing one byte of data is fine If I try to write multiple bytes into Tx FIFO two uncommon things are happening.
    (1) Either there is no clock and data.
    (2) Or there is clock and data but only the first byte which I wrote into the Tx-FIFO is appearing on the data mosi line.

    I posted this issue in xilinx forums but no solution hence I am posted it here again. 

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  • 0 in reply to Former Member

    Yes I did look at the example code given in the SDK and also I did study the documentation. The problem is quite simple. I am trying to send data with manual start enabled. writing one byte of data is fine If I try to write multiple bytes into Tx FIFO two uncommon things are happening.
    (1) Either there is no clock and data.
    (2) Or there is clock and data but only the first byte which I wrote into the Tx-FIFO is appearing on the data mosi line.

    I posted this issue in xilinx forums but no solution hence I am posted it here again. 

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