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Topic: Simultaneous ADC (Read 1 time) previous topic - next topic

blaqradio

HI

Anyone can suggest a Simultaneous Analog to Digital Converter chip with possible 8 analog inputs and 8 output pins at a low price please

Thank you

dave-in-nj

digital means a stream of data, one after the other.  you cannot dump 8 steams of data onto one stream at exactly the same time.  much like you cannot think 8 thoughts at the same time.

look up XY PROBLEM

what are you REALLY trying to do ?


blaqradio

I know not related this forum but I am trying to measure current and voltage from Grid tie,Generator and PV solar using Current and Voltage (sensors)Transfomers on Raspberry Pi but the problem with raspberry pi doesnt take analog inputs , so i need ADC that will convert inputs simultaneously then go straight to my PI

DVDdoug

I'm not sure what chips are available.   It's possible to multiple DAC channels simultaneously, but in your application is a few microseconds going to make a difference?

On the output side, you won't be able to read/process the data simultaneously unless you use multiple processors.   Typically if you do clock all of the reads together, you read the outputs one at a time in-between reads.

graynomad

I've only aver seen simultaneous ADCs in a dual configuration, never 8 channels. And they are always really fast (and expensive) and designed for scopes etc.

Just use two ADCs and wear a few uS between readings, I can't imagine it will matter.

Also IIRC I think you can get ADCs that have a sync or "take reading now" pin, you could use them.
Rob Gray aka the GRAYnomad www.robgray.com

Grumpy_Mike

You do not need the readings to be simultaneous. If you are using a Pi then simply connect a A/D converter on the GPIO pins. You can buy one from Pimoroni or for less than £2.00 add one yourself. See the current MagPi magazine ( free download ) for an example of a 4 input  A/D in the Mike's Pi Bakery slot.

dlloyd

#6
Sep 08, 2016, 02:24 pm Last Edit: Sep 09, 2016, 04:47 am by dlloyd
I think the OP means simultaneous sampling, not simultaneous readings (please clarify). If so, then there are many ICs to choose from. Note that the Arduino Due and possibly other boards can do this inherently without an external ADC.

Grumpy_Mike

Thanks, spelling error due to crap spelling corrector on iPad.

But this is a classic beginners mistake thinking that samples have to be taken at the same time.

While the Due does have a 12 bit ADC and a 10 bit ADC I do not know how to use them both at the same time. Have you got any examples?

dlloyd

#8
Sep 08, 2016, 03:16 pm Last Edit: Sep 09, 2016, 04:53 am by dlloyd
Quote
While the Due does have a 12 bit ADC and a 10 bit ADC I do not know how to use them both at the same time. Have you got any examples?
I've used the Due's PWMC but didn't work with the registers that enable and use simultaneous sampling. I haven't checked if someone has already written code somewhere that uses this feature, but its available in the dozens of registers that work with the PWMC.
Whoops ... wrong peripheral.

mrburnette

Quote
Analog Devices simultaneous sampling precision A/D converters offer two to eight discrete ADCs in a single package, allow two to 12 channels, and span resolutions from kSPS to 5 MSPS.
A place to start the search is the Analog Devices link here.

Once you narrow down a chip or two, then start a search for a competitor brand to determine if you can get the pricing down.


Ray

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