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Topic: how to connect a AD9225ARS 12-Bit, 25 MSPS A/D Converter with arduino (Read 297 times) previous topic - next topic

nilmourad

I have an AD9225ARS A/D Converter 12-Bit from one analog input up to 25Mhz to a 12bit digital parallel output
I just need only used 8bit on the output for AD9225 for connect directelly one port for arduino UNO or mega
(lsb from 0 to 7 or msb from 12 to 5 digital output ,by choice)
I want to make an oscilloscope on a 16bit tft display
If it is not possible on Arduino of memory size, uc speed and the length of the register and ....bla bla bla
I have an STM32f103C8T6
anyone help me ? sketch and library + schematic , ... any think about this IC.

freaklabs

Hi. You would need a parallel memory bus on the chip and I don't think the STM32F103C8T6 has a parallel interface. You would need to choose a different chip that can support an external parallel memory bus or use programmable logic as glue logic to interface the ADC to that chip.
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nilmourad

Hi.
I would like to connect it in parallel with an 8bit bus and ignore the remaining 4bit
just I need a library and a code for this chip
thanks

freaklabs

Hmmm....then perhaps you just want an 8-bit ADC? I think tht would be a weird way to connect up the chip and probably risky. But then again, never hurts to try. The larger issue is that you will be getting data coming in at 25 MB/sec which is quite a load for a microcontroller. You'll need to figure out how to process data that quickly. You might need to burst it in, have some programmable logic to calculate an average, or just sample slower. Might also want to check out if you can use the internal ADC to prototype your design and then scale it faster from there. Most oscilloscopes with decent speeds use FPGA to interface the ADC since the data rates are so high.
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MarkT

Your first problem with this chip is providing a proper clock drive to it.
The second is that its a very complex high speed device designed for performance at the expense
of simplicity - the datasheet is a long complex document full of stuff that is important to get proper
performance from the chip.  Nowhere is the idea of running it slower than 25MSPS even mentioned
AFAICT.

You need something much simpler like a SAR ADC with fast SPI interface.

Aim for more like ~100kSPS sample rate on an Uno or Mega, it has no DMA hardware and very little
RAM, so its not designed for high speed data acquisition.

And you'll need to think about front-end analog processing (anti alias filtering, attenuation, protection).
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