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Interfacing high speed ADC to microcontroller
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tszaboo:
Hi. There is a project I'm investigating. One of the options is to interface a high speed ADC to a Microcontroller. We are talking about 30 MSPS 12 bit into an ARM cortex M4, running at about 120 MHz.

My question is not about how to do it. This would be PITA and it probably wouldn't work in the end.

My question is about proving that this is a really bad idea. Because there are ADCs with parallel CMOS interface, I actually need to give reasons why this wouldn't work, before we could go with the FIFO/DSP/FPGA and other routes. And it should work from less than a watt of course. Any white papers or application notes or articles? Thank you!
voltsandjolts:
I have no experience of high-speed ADCs feeding uCs.
I do have experience of manipulating management decisions to make them go my way!
In this case I would say something like 'Programmable logic offers a development process with reduced risk of systemic errors and thus improved estimates of costs going forward, particulary in respect of certification for regulatory compliance where the lower clock rates required by custom logic reduce the potential EMC profile'
It's kinda fun, isn't it?
ataradov:
Microchip SAM S70/E70/V7x have parallel capture interface that can capture data on external clock. In combination will the DMA, it will handle 30 MHz without any issues. Obviously once you run out of buffer memory, there will be a gap in the capture. There is no way you will be able to process that stream in real time.
moffy:
And what do you want to do with the data after you get it into the micro? NXP have an LPC4370 processor with integrated 12bit/80 MS/s ADC but it's what you want to do with the data. If you need to process at that rate or get it out that can be an issue unless it's just burst mode.
DaJMasta:
Would it suffice to tell them that unless all the processing and communication that they want to happen would have to happen in three clock cycles because on the fourth you'll be getting another package of data from the ADC?


DMA can help a bit, sure, but if they want continuous data transfer, a 120MHz single threaded chip and a 30MHz data input doesn't leave that much time for actually doing something with the data.
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