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Is ADC DAC Pi what i need ?

2392 Views - Created 05/10/2015

31/08/2015

Posted by:
Morten Hundevad

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Hello

I am trying to come up with a slim HMI with "plc", and none of the existing HMI panels with plc are small and or cheep enough.

So i am looking at Raspberry Pi. I need to have Analog out, and digital in/out

Analog out properly need to be 0 - 10v or 0 - 20 mA, standard for the equipment that need to be attached.

Now i am looking at this since Raspberry Pi do not have analog out by default.

https://www.abelectronics.co.uk/products/3/Raspberry-Pi-Model-A-and-B/39/ADC-DAC-Pi-Raspberry-Pi-ADC-and-DAC-expansion-board

This may be an option? could I use this board with something like:

https://www.tindie.com/products/ozzmaker/piscreen-35-tft-with-touch-for-the-raspberry-pi/

or

http://www.adafruit.com/products/1601

I am new to Raspberry Pi, so i do not know what "fall pits" there are or what limitations are.

-Thanks

31/08/2015

Posted by:
andrew

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Location:
United Kingdom

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Hello

I don't think the ADC DAC Pi will work with either of those displays as they both use the SPI port and so does the ADC DAC Pi. You can only have one SPI device connected to the Raspberry Pi so there would be a conflict between the two expansion boards. The analog out on the ADC DAC Pi also only goes up to 2.048 volts.

AB Electronics UK Tech Support

31/08/2015

Posted by:
Morten Hundevad

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Is there any other options you see that i could use ?. the display is a must, just like the analog out is a must.

As for voltage i could make an "amplifyer" or something correct ? or use 2.048 V and add something that makes it 0.20 mA would propearly be the simplest.

Any sugestions would be aprisiated. 

-Thanks

31/08/2015

Posted by:
andrew

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You could try finding a DAC chip that uses the I2C port instead of SPI.  

Texas Instruments do several I2C DACs, http://www.ti.com/lsds/ti/data-converters/precision-dac-less-10msps-products.page#p158=Serial I2C so it may be worth trying to find one that fits your needs and order some free samples to play with.

As the I2C port on the Raspberry Pi is 3.3 volts you may need to use a level shifter if you choose a DAC that works at a higher voltage.

AB Electronics UK Tech Support

31/08/2015

Posted by:
Morten Hundevad

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Could it be something like this?

http://www.adafruit.com/products/935

and something like this for input ?  or is there only one I2C also ?

https://www.adafruit.com/products/1085

31/08/2015

Posted by:
andrew

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United Kingdom

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Those two should work together and they are both 3.3V compatible so you can control them directly from the Raspberry Pi I2C interface.

AB Electronics UK Tech Support

31/08/2015

Posted by:
Morten Hundevad

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Thanks for your support!!!

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