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No repsonse from AD5272

Question asked by KMC500 on Nov 6, 2013
Latest reply on Nov 12, 2013 by KMC500

Hi ALL,

 

I am having some difficulty updating the output resistance value from the AD5272.

 

I have initiated communnications over the I2C. I have proven it is addressed correctly, the system is receiving acknowledges and able to complet e the 3x packet transaction as described in the datasheet. This has been measured with a scope.

 

I have tried to run the system using configuration bits to define direct update of the RDAC register and also updating via the 50TP spaces but I always have the default output of 10K.

Circuit.png

Circuit Shown above.

 

SCR26.PNG

And Data Plot showing SCL & SDA lines at a frquency of 80kHz, data sent in summary is as follows:

 

P1: 0101100000 - Adress, Write & Ack

P2: 0000001110 - Config to Update RDAC, D9 & D8 = 1, Ack

P3: 1111111110 - D7-D0 = 1, Ack

End

 

This should write 1023 to the RDAC giving full scale. Regardless of what data I send the output is fixed at 10K.

 

It may be that I am doing something obviously incorrect here but I would appreciate anyones feedback who knows this part well.

 

Many thanks in advance,

 

KMC

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