ADAU1701 selfboot

Hello PolyA,

One of our older engineers did try to program several SigmaDSPs all at once and it worked but it is not advisable to do in I2C mode. This is because the DSP has to provide an ACK and so multiple processrs will respond at the same time so it did work but there is risk that it might not do it every time. If you use SPI then there is no acknowledgements from the DSP so you can pull down all the CS lines and broadcast the data to all of them. You can use a GPIO line signal that the program is running so you can verify that all the processors got it.

For selfboot it is a different situation. The DSP will become a master and start reading from the EEPROM. The timing of when the DSP starts this has to do with the PLL lock time and how fast it did the initialization so getting that timing correct is not likely. Having two masters is a problem. So if you want to do this it would have to be a system controller that programs the parts.

If you do not want to use a controller then the recommendation is to use an EEPROM for each DSP. The image in the EEPROM can be the same.

Now, as I think about it, I like creative solutions. There are I2C routers/switches. You could have one DSP setup to boot off of the one EEPROM with a switch set to that DSP. Then when the DSP boots up it changes a GPIO output that was holding the I2C switch in one setting and it was also holding the other DSP in reset. Then When it changes the I2C switch is flipped and the second DSP goes out of reset and will boot off of the same EEPROM. So there are some parts required to do this so it might not make any sense from a cost and complexity viewpoint. Might be easier to just use two EEPROMs

Dave T