How can I use two AD7606 in one Atmega128?


I want to use 16 channels ADC data. So I select AD7606.

After ADC from AD7606 (serial mode), datas are connected to Atmega128

Atmega128 transmits data to MFC viewer by bluetooth

When I use just one AD7606, I can see analog input data from MFC viewer.

However, when I use two AD7606, i can't see ADC data from second AD7606 in MFC viewer.

Second AD7606 pins (DoutA, CONVSTA,B, SCLK, Busy) were connected to Atmega128 same pins which first AD7606 pins were already connected except for CS pin (It is connected to different pin in Atmega128).

I coded like this. When first AD7606 CS changes low to high, second AD7606 CS changes high to low.

I thought second AD7606 will work ADC after finishing first chip ADC using CS pin.

But when I input analog data to second AD7606, I couldn't see any data from MFC viewer...

How can I solve this problem?? plz help me..

Thank you. 

  • Hi,

    I moved this post to the precision ADC space, someone here should be able to help with your question.



  • Hi,

    still having trouble with AD7606? ;-)

    Connecting CONVSTA/B and SCLK to the same pins of the µC is ok, as they are inputs of the AD7606. No problem to drive them in parallel.

    Connecting DOUTA/B of both ADCs to the same pins of the µC will work, if you realy can ensure, that the CS for for both ADCs are never active at the same time. Then DOUT of the inactive ADC will switch to high-Z and the active ADC can drive out its data.

    Connecting BUSY in parallel is not so nice: this are two outputs driving against each other. It will work, if both ADCs drive the identical data on BUSY (as they are started at the same point in time and their conversions should take more or less the same period of time). But if you anyhow rely on the fact, that both busy lines drive the same data, then you could also evaluate a single BUSY line without conneting two outputs to each other.

    So the connection of your signals may not be ideal, but it should nevertheless work if you really ensure, that at least one of the CS-lines is always inactive. (If I misinterpreted your signal connections, a small schematic would be helpful).

    You wrote, that you can see "no data" for the second ADC. What exactly does that mean? Do you receive data, but it is constantly zero? That would point to a problem of the ADC readout (like incorrect sequence on the CS-signals). In that case, some scope-shots of the serial readout pins on your board would help to narrow down the problem.

    Or does "no data" mean, that really no data is received? That would point more to a problem of your data transmission from µC to PC (i.e. of the firmware).

    best regards


  • Hi,

    How is your setup? If you're still having problems kindly share your schematics and some scope shots of your digital signals so I can take a look.



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