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Finding an ADC

sbkenn

Hi guys.  Does anyone know of an 8-bit, 8 channel ADC with I2C interface, AND a trigger input to sample/hold and start the conversion.  I want to measure, synchronised to a point in my code on a highly dynamic channel.  The only ADCs that I have found where I can precisely time the latch are parallel i/o ones.

The whole system is timing critical, so I want to offload the ADC stuff from the main uC (a 2560 at present).

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  • Shane,

     

    I have not come across anything like that (and I too have looked).  On a project that I was working on for a client, with limited I/O on the processor, I built a CPLD controller that would trigger multiple parallel ADCs and return the results via an I2C interface.  This worked out very well and was not that difficult to code (in VHDL).  I don't believe that I have VHDL any more as it was all on a hard disk that crashed. You might be able to find something like that online.

    Best of luck!

    Gene

  • in reply to genebren

    Thanks. I am not actually short of i/o, so can use a parallel device.

    Serial is tidier though, and leaves more options for reducing size.  I do

    like to push boundaries too.

  • in reply to sbkenn

    What you want to do isn't difficult with a more sophisticated processor. It might be time to consider moving away from Arduino and on to a processor with a modern fast ADC with DMA and timer based triggering. These are not uncommon features. Try looking at ST ARM Cortex based processors available on their Nucleo series of very cheap dev boards. Free software tools are available.

     

    You could use a Nucleo board as an I2C or SPI linked peripheral to your Arduino if that makes the system easier to develop.

     

    MK

  • in reply to sbkenn

    What about using an I2C to parallel chip like an MCP23017? Saves you pins on the micro and lets you use any parallel ADC you come across.

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