ADAU1467 SPI clock Selfboot

Hi

ADAU1467 works as SPI master when selfboot is enabled, but how to configure SPI clock frequency for the SPI master?

I tried to look through 1467 datasheet and past EZ threads, but couldn't find it.

Regards,

Tomoto

  • 0
    •  Analog Employees 
    on Jan 18, 2021 6:11 PM

    Unfortunately, there is no way to change the SPI (or I2C) bus speed during self boot. It is just a state machine that loads the code. 

  • 0
    •  Analog Employees 
    on Jan 19, 2021 1:23 AM in reply to Ken.M

    Thanks Ken-san,

    I just want to understand how the selfboot function(state machine) works.

    As far as I checked with 1467 EVB and SigmaStudio 4.6, Actual SPI clock monitored by a scope

    - During Selfboot write      : around 10M regardless of "Write Speed" setting, 

    - Selfboot enabled(read)   : around 10k if "Write Speed" was below 1,000k

    - Selfboot enabled(read)   : around 500k if "Write Speed" was 10,000k 

    Could you clarify this? 

    Regards,

    Tomoto 

  • 0
    •  Analog Employees 
    on Jan 22, 2021 10:29 PM

    Hello Tomoto-san,

    Look at figure 39 in the datasheet. The initial SPI/I2C speed is fixed in the firmware. It is very low speed but it only loads in the 16 byte header from the hex data file. In that header are four bytes that setup the serial port speed for loading in the rest of the hex file. It is not a straightforward number for setting up the speed but you can set this up in SigmaStudio.

    Now I have to say I am not 100% that this has not been changed with recent revisions. I do not have time to check this at this time. In SigmaStudio, you setup this speed in the EEPROM Properties. You find it here:

     

    When the window opens up you set the speed here:

     

    You may have more questions but this will get you started.

     I will have to look up the information of how the speed is calculated. As I recall it is something like the number of clock cycles for the clock to be high and then the number of cycles for it to be low. So the number in the hex file is not just a number for the speed. 

     Dave T