Other Parts Discussed in Thread: LM317
Tool/software: TI C/C++ Compiler
Hello,
Currently, I am working on a project based on weight change measurements. I have tried some different ways to amplify the signal from 10kg load cell 1mv/V to be read using an Arduino UNO on my prototype. Finally, with ADS1232 (WCMCU-1232) I got the best measurements, but there was a little bit of noise. Sometimes with no reason weight measurements could gain or lose non-logical 20 or 30 grams. So, looking for the best step measurement I tried different electronical connections until I found the next schematic in a forum (https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/73/1817.SCH.jpgwith some changes that I applied like all supply connections are connected to 5v regulator (Lm7805), except DVDD (it is connected to 3.3V LM317 regulator). Finally, Arduino is connected to another 5v source (LM7805), and all ground connection between them.
This connection made that the measurements were a few better than before, now I have sometimes 0.3 or 0.5 gr in changes. But then, I found a new issue.
For some reason, where everything is connected to each supply source, the PDWN pin gives a 5v output that makes turning on the Arduino (when Arduino is off), what is worse, when the supply source of Arduino is turned on becomes the 3.3v input in a 4.2V input. This could be confusing, but it is happening, and as a result, if I am having e.g 5000 gr of weight, automatically gives 250000 gr or something crazy value like that.
I think of course could be a problem with the source supply, but I have verified all connections, and everything it is ok, and for that reason, I have used different supply sources.
So, my question is. Do you know how to solve this problem with the PDWN pin? maybe some different connection to try or what is the importance of this pin? may be connected with a diode or filter?
Thank you, so much for your time.
Duvan.