Selfboot + writeback + I2C commands

I'm using an ADAU1701 in selfboot mode, using my uc to emulate the boot EEPROM.

At the end of selfboot sequence I add the multple writeback command (0x04) and I recall writeback every 100ms to read values from my DSP.

Between a writeback and next one I want to send command to my DSP, such as mute and routing commands, so I must send as master commands to ADAU1701.

So, I start in selfboot mode and I use writeback, but I also send command as in I2C mode (being careful that I'm not writing as master during selfboot and writeback).

Datasheet said:

"After the ADAU1701 finishes self-booting, additional messages can be sent to the ADAU1701 on the I2C bus, although this typically is not necessary in a self-booting application. The I2C device address is 0x68 for a write and 0x69 for a read in this mode."

So, it's possible to write and read by I2C as master. Then:

"The ADAU1701 is a master on the I2C bus during self-boot and writeback. Although it is uncommon for an application using self-boot to also have a microcontroller connected to the control lines, care should be taken that no other device tries to write to the I2C bus during self-boot or writeback."

I have respected also these conditions, but commands don't work.

Have I to do something else, like to set low SELFBOOT pin? Are there some special procedure to become a master starting in SB mode?

Thank you

Stefano Rossi

  • The SELFBOOT pin is only used on power-up to indicate whether the IC should selfboot from an EEPROM or not. After the initial power-up, the state of this pin doesn't matter. The system you have set up is a multi-master I2C bus, which the ADAU1701 is not designed to support. The master I2C circuit of the ADAU1701 expects that it is the only master on the bus. In your design, it seems likely that there is some interference between the two masters.

    I would strongly recommend that you re-evaluate the need for selfboot in your design. Since you already have a microcontroller on the board, it would be best if that's use for booting the ADAU1701, rather than trying to selfboot from an EEPROM and then switching over to a multi-master control system.

  • 0
    •  Analog Employees 
    on Jun 4, 2015 9:37 PM over 5 years ago

    Hello Stefano,

    I ran across this post today and thought I would clear something up. When the 1701 is in Writeback mode it will act as a master. I suggest you do not use the Writeback feature when using another master on the bus.

    Dave T

  • 0
    •  Analog Employees 
    on Aug 2, 2018 4:17 PM over 2 years ago
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

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    EZ Admin