DFRobot 16-bit ADC module

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Hi team,

I tested Gravity 1115 ADC module Gravity: I2C ADS1115 16-Bit ADC Module (Arduino & Raspberry Pi Compatible) | DFRobot DFR0553 | Core Electronics Australia with a non-Gravity MQ-137 sensor and it seems to be working fine - giving same readings as when I tested it with Adafruit ADC and Logic Level Converter.

My question is regarding LLC. Do these Gravity 1115 ADC modules come with built-in LLC since they are meant for Raspberry Pi? If not, any harm in using these without an LLC?

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Hi Riddhi,

I would imagine so, there is a diagram where the module is connected to an Arduino and a Raspberry Pi (with logic levels of 5 and 3.3v respectively) They do feed through the voltage its supplied directly to the analog sensor though so be weary of that!
In short, there wont be any harm in running it at 3 or 5V.

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Hi Riddhi,

Looking at the schematic for the ADC, the SDA and SDL lines are connected to 3.3V via pullup resistors so this particular device should be fine to connect to 3.3V logic, even when it is powered via 5V.

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Thanks again Trent and Liam,

I can confirm that it is all working fine as you suggested. For the above setup, I have a project compatibility question for the MQ sensor and breakout board on Core Electronics website that are listed here:

https://core-electronics.com.au/gas-sensor-breakout-board.html and
https://core-electronics.com.au/ammonia-gas-sensor-mq-137.html

Above two combined seem to be different from the following product that we tested our project setup with. If I put it with my very little hardware knowledge…the breakout board seem to be missing the whole lot of things that are on the board in following product. My question is, will above two combined, work same as the mentioned product? What is the difference there?:

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Hi Riddhi,

Our site lists the MQ-137 sensor as a standalone product which will have an output based on the datasheet for the sensor.

The breakout board just provides a convenient way to connect to the terminals of the MQ sensor.

The eBay product does not have any details of its output specifications but it appears, judging from the LM393 circuit on its breakout board, that it has a comparator circuit that drives the output of the module.

While both of these products do use the same sensor, the added circuitry on the eBay module will change the output you get from it as you aren’t getting the raw output straight from the sensor.

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