ADS1115 issue while taking results

Thread Starter

RenesasTaac

Joined Dec 26, 2016
2
Hello Everyone,

I am facing an issue with ADS1115 ADC which is 16 bit ADC. I am able to communicate mircocontroller and ADC. I am even able to get the ADC counts. Though counts are fluctuating I have used averaging method to get proper counts.

The PGA is +/- 2.048. I am using channel 0. I am getting below results,

mV ADC count

200 200

300 300

1000 1000

1024 1024

1058 1058

To convert ADC count into voltage I am dividing ADC count by 1000. My question is how to get fourth digit after decimal point.

Suppose mV=1058.5 I need converted value should be 1.0585.

As the ADC is 16 bit, can anyone please explain me how to get fourth digit after the decimal point.
 

ericgibbs

Joined Jan 29, 2010
13,242
hi RT,
What is the input voltage range [max] to the 16 bit ADC.?
E

EDIT:
Have you considered multiplying the ADC input voltage by 10, using a OPA.?
So your ADC count becomes 10585.
 
Last edited:

ebeowulf17

Joined Aug 12, 2014
3,282
Are you sure you don't have an ADS1015?

Sounds like a silly question, but the numbers match perfectly. A 12 bit ADC yields 4096 values, so with the PGA set for +/-2.048V input range, each bit corresponds with 1 mV, which perfectly matches your readings.

Your current behavior is exactly what would be expected from a 12 bit ADC, but is totally inexplicable (at least to me) with a 16 bit ADC.
 
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