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adau1701 no i2c signal in selfboot

Question asked by Jaroon on Jul 23, 2013
Latest reply on Aug 5, 2013 by BrettG

dear madam, sir,

 

I'm new to this forum and I have a question.

I've designed test board with the adau1701 dsp with the intention to use it in selfboot mode. I based this design on the selfboot design in the datasheet.

The gpio's and I2C are all brought to headers and all the filters and oscillator are onboard. The selfboot pin and the /reset are pulled up with a 10K resistor, the I2C wires are pulled up with 2k2 resistors.

I copied an eeprom from a working (commercial) board from which I want to boot, I2C addresses are the same.

When I start the board with selfboot and WP high there is no I2C signal at all apart from the 3.3v pull-up (checked it with a data logger), i can imagine that using eeprom data from another board is little to easy, but was expecting at least a little communication but the I2C lines are completely dead.

I've checked the oscillator with an oscilloscope, this runs fine (12.228Mhz, 2v pp), all voltages are according to specs. When the board is reset it draws about 70mA after reset it draws around 100mA. I've checked all pins and connection (many times) they all work, all gpio's measure 3.3V.

Then I changed the chip for a new one, this one had the same problems.

Now I'm afraid that I might have fried both chips with my hot air tool (max 265c), is this possible? I never had any problems with it before.

Or could it be that I am missing something obvious, or maybe my whole set-up/idea is wrong?

I don't have a way to connect the board to Sigmastudio.

 

I understand that these questions are somewhat hard to answer without having the board at hand, but I hope you can help me.

 

Kind regards,

Jeroen

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