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ADAU144x Evaluation Board (EVM) Self-Boot Mode

Question asked by IanH on Apr 12, 2011
Latest reply on Apr 13, 2011 by BrettG



I have a EVM for the ADAU1445 which functions very fine when downloading my application to via USB.


But I have followed the thread on setting up self boot..


yet I am not able to get the EVM to self boot.


I have checked the signals at the EEPROM when programming the latest configuration to EEPROM and the signals look fine (SCL and SDA) using SigmaStudio 3.4. I have the LK15 and LK16 fitted to connected the EEPROM to the ADAU1445. You can see that in the attached Programming I2C.bmp.



I have set the self-boot switch to off and confirmed it is high.


The problem appears to be with the EEPROM reading after reset. The SCL toggles at 375kHz (within spec and appears to have the 3/8th duty cycle). But the SDA line does not seem to have sufficient strength to pull high enough. You can see that in the attached Selfboot I2C.bmp.


Why is there no pull up on the open collector SDA line?

Fig 47 of the UG-032 ADAU144x EVM User Guide does not show a pull up in the schematic.

The Microchip 24AA256-I/ST EEPROM has an open collector output and according to the datasheet requires a 2k pullup for 400kHz operation.


Is this a known fault in the EVM board and should I be fitting a 2k pullup myself to correct this issue?



Ian Hickey