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I2C addressing problem

Question asked by Nando.One on Sep 8, 2012
Latest reply on Sep 8, 2012 by Nando.One

Hi There, how are you?


I recently designed my own SigmaDSP board featuring 2x ADAU1701 and a PIC24F. Very well, everything working great, except that I can NOT address the DSPs separately:


DSP 1 has both ADDR0 and ADDR1 tied to the ground, so its address is 0x68. DSP 2 has ADDR0 tied to +3V3 and ADDR1 tied to GND, therefore its address should be 0x6A. Correct?


The thing is, when I send I2C commands to DSP1, using 0x68 physical address, BOTH DSPs respond. If I use 0x6A as address, none of the DSPs respond. Weird thing is that I measured ADDR0 of DSP2 at the PIN and it is indeed tied to +3V3, so it can't be a hardware problem.


Any ideas? It's driving me crazy!