Gravity: I2C ADS1115 16-Bit ADC Module (Arduino & Raspberry Pi Compatible) (DFR0553)

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DFRobot I2C ADS1115 16-bit ADC module can accurately collect and convert analog signals. Through this ADC module, Raspberry Pi can easily use a wide range of Gravity…

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Product is garbage. It does NOT provide 16 bit. At max range 16 bits means 0.18mV resolution. This adc won’t read lower than 1mV.
Edit - See my reply below.

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Hi David

I think this is probably a bit unfair.
at 16bit if the input voltage = the reference then the ADC will output a number 65535 with lower input voltages producing numbers progressively lower down to Zero. The ADC only produces a number, what is done with this is up to the user.

I would suggest the library then converts this result to millivolts for manipulation or whatever. From the example it is obvious the reference is 5.0V

Now a resolution of 1mV in 5000mV is a resolution ofd 0.02%. Just how low a resolution and accuracy are you after. I would suggest if you have a lab or something and want better you may have to write your own library.

I may be entirely wrong here and stand corrected if this is so.
Cheers Bob
Edit;
If you click “more documents” in Core description there are a couple of examples which suggest a resolution of 1mV is correct for this device using the supplied libraries.

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Do you mean that you can’t get readings between 0mV and 1mV? The device will always return an integer reading, but what that means as a voltage depends on your settings for the thresholds and the gain. What have you set the thresholds and gain to when you are trying to read voltages less than 1mV?

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What is the benefit of using this? I mean Arduino has it’s own ADC channels. Is there any benefit of using this module instead? Thank you.

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Hi Teplia
The Arduino ADC is 10 bit and returns 1023 steps. This unit is 16 bit and returns 65535 steps. Also most of the RPi don’t have a built in ADC so something like this is needed for analog inputs.
Cheers Bob

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I am using the ADC with a Nano to build a milliOhm meter (short finder). With the Nano ADC the resolution limit is 0.05ohm. With the ADC it should be better than 0.001ohm. Note that I am not after precision - just the resolution to detect very small resistance differences.

At the default gain (6.14v) the resolution is supposed to be 0.187mv (not 1 mV). The DFRobot library will only return integer mV values regardless of gain. I switched to the Adafruit 1X15 library (for their version of the ADC) and their function returns integer steps and a function that converts the steps to mV which provider decimal values. So it appears the ADC is fine - it’s just the DFRobot library which has the limitation (or it’s just not well documented).

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Thanks a lot.

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