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Hot!dsPIC33CK: Am I interfacing my dsPIC33CK256MP506 to 2-channel 8-bit AD9288 ADC correctly?

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firmwareNovice
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2020/05/23 17:16:15 (permalink)
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dsPIC33CK: Am I interfacing my dsPIC33CK256MP506 to 2-channel 8-bit AD9288 ADC correctly?

 
Hi All,
 
I need to sample and convert two analog channels simultaneously, at sample/convert speeds > 10Msps.

I don't need the ADC resolution to be super high, so I'm planning on using 8-bits.
 
What I've got so far is a dual-channel, 8-bit, AD9288 ADC, which performs a sample/convert sequence on the rising edge of an input sample clock. I'm planning on using the REFCLKOUT feature from the dsPIC to provide this ADC sample clock, which I've tested on my current board and I know works.
 
 
My question is this. Can I route both sets of 8-bit conversion outputs from the AD9288 to a single, 16-bit port on my dsPIC and perform a port read (PORT D in my case)? And then do some bitwise ANDING and 8-bit shifting to separate the data? Kind of like the pseudocode shown below:
 
(Use DMA to transfer PORT D data to uint16_t AD9288_ADC_DATA)
(DMA transfer done interrupt)
uint16_t AD9288_ADC_CHANA_DATA = AD9288_ADC_DATA && 0xFF00;
uint16_t AD9288_ADC_CHANB_DATA = (AD9288_ADC_DATA && 0x00FF) << 8;
 
If it's not too much trouble for anyone to answer, would this data acquisition scheme work? I've attached a picture of a partial schematic here. Hopefully, the quality is not too poor.
 
 

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    ric
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    Re: dsPIC33CK: Am I interfacing my dsPIC33CK256MP506 to 2-channel 8-bit AD9288 ADC correct 2020/05/23 17:22:09 (permalink)
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    Why are you putting the data into the upper 8 bits of a 16 bit variable, rather than straight into an 8 bit variable?

    I also post at: PicForum
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    firmwareNovice
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    Re: dsPIC33CK: Am I interfacing my dsPIC33CK256MP506 to 2-channel 8-bit AD9288 ADC correct 2020/05/23 17:26:09 (permalink)
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    Hi Ric,
     
    I'm using the microchip DSP library function, vectorCorrelate, which works on 16-bit fractional data. So that's why I'm using storing all the results in 16-bit data buffers.
     
    Unless the vectorCorrelate function works on 8-bit data (which I haven't tried), which would be great, because then I could gather more data!
     
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    ric
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    Re: dsPIC33CK: Am I interfacing my dsPIC33CK256MP506 to 2-channel 8-bit AD9288 ADC correct 2020/05/23 17:31:41 (permalink)
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    ok, sounds like it probably a valid thing to do then :)
     
    post edited by ric - 2020/05/23 17:34:51

    I also post at: PicForum
    Links to useful PIC information: http://picforum.ric323.co...opic.php?f=59&t=15
    NEW USERS: Posting images, links and code - workaround for restrictions.
    To get a useful answer, always state which PIC you are using!
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