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ADC Pi Plus and Alphasense AFE

1311 Views - Created 28/02/2017

28/02/2017

Posted by:
wazabi

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Hi there,

I want to read data from an AFE board on a Raspberry Pi 3: http://www.alphasense.com/WEB1213/wp-content/uploads/2015/11/AFE.pdf

My understanding is that the ADC Pi Plus is what I need.

However, being a newbie in electronics, I don't know which pins to use on the ADC Pi Plus.

At the moment, the AFE is connected to an ADC Adafruit : https://www.adafruit.com/product/1085

which is connected to the SCL / SDA pins of an Arduino.

Any help will be much appreciated.

Thanks!

 

28/02/2017

Posted by:
andrew

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Location:
United Kingdom

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Hi

To connect the AFE board to an ADC Pi you will need to connect the VIN pint to the 5V pin, the GND to GND and the sensor outputs would go to the analogue inputs on the ADC Pi which are labeled 1 to 8 in the same way as you are currently connecting to the A0, A1, A2 and A3 pins on the adafruit board.

Do you know what the maximum output voltage will be for the sensor outputs?  If it is less than 2.048V then the ADC Differential Pi may be a better option as it has improved accuracy at lower voltages.

AB Electronics UK Tech Support

28/02/2017

Posted by:
wazabi

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Thanks, andrew!  Your answer is very useful.  Maximum output voltage from the AFE is 5V so ADC Differential Pi is not an option I am afraid.

 

 

28/02/2017

Posted by:
wazabi

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Also, assuming I want to power the AFE with the Raspberry's power supply, which GND/+5V pins should I target on the ADC Pi Plus:

- the ones sitting next to the 1-8 output pins?

- or the ones sitting on the GPIO pins?

 

(in other words, are the GND/+5V pins next to the 1-8 pins for input or for output?)

 

28/02/2017

Posted by:
andrew

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Location:
United Kingdom

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The GND and 5V pins on the ADC Pi Plus are connected directly to the GND and 5V GPIO pins on the Raspberry Pi the AFE can be powered by either sets of pins.  If you do use the 5V and GND on the ADC Pi then the distance between the ground on the sensor board and the ADC ground will be shorter which may help reduce the amount of noise on the ADC inputs.

AB Electronics UK Tech Support

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