peppe8o
commented
9 months ago Hi @chsims1. The current development, based on my MQ-2 with Raspberry PI Pico tutorial, wants to make the job as simpler as possible also for beginners. You are right, having 5V input/output would be better to get more precise values, and a bi-directional logic shifter would help on this as RPI Pico deals only with 3.3V logic, with the 5V port useful only to power external sensors. Moreover, we should also consider the limited precision that a few dollar-sensor can achieve. I think this sensor could be useful just to set a warning when gas levels rise over a specific percentage, without caring too much in checking if the values are really precise. Anyway, it would be interesting to know if someone has professional equipment to compare the results of this sensor with professional ones. Thank you for your comment and I would like to know your opinion based on this
I was under the impression that the MQ-2 input & output voltages were all 5V. The calibration is likely to change with a 3.3V supply, although if it is still linear then this might not be a problem. What about the voltage at the Pico ADC pin?
Any reason other than simplicity that you didn't include a simple logic level 5V to 3.3V converter?