I'm trying to get my Arduino Nano 33 IOT to pick up the signal received from my TE Connectivity FX292X-100A-0100-L load cell, then send it to an app, but I want to make sure it can receive the signal first before I continue on.
Attached is my current circuit. I am using an AD623ANZ Instrumentation amplifier (datasheet).
I'm powering said circuit by just connecting the arduino to my PC USB port. I then use a simple, read A0 and println piece of code, which gives me random values between 0 and 14 and seems to have no response to increase or decreases in pressure.
I've have not done any project like this so any help would be greatly appreciated.
A HX711 board from Sparkfun would have been a better choice.
That's the only HX711 board I know off with a separate 5volt supply for the load cell and a 3.3volt for the digital output for your 3.3volt processor. Common HX711 boards can't be used.
Leo..
I bet @JCA34F hit the nail on the head [*], but also, your figure doesn't have the decoupling capacitors shown in the datasheet Figure 43. They may be essential for proper operation.
[*] With Vref=0v as in your current setup, if Vdiff goes "negative," then the output will try to swing below 0v, which is impossible. Hence (possibly) your always small result. If that is the case, then swapping inputs should make the output swing above 0v.
If your load cell output needs to swing both ways, then you should set Vref to half of the supply voltage.
And even if your load cell output only goes one way, even though the AD623 is a "rail to rail" device, it may make sense to set Vref higher than zero, to allow for a possible small negative differential output at zero load, and other offset effects.
In any event, be sure you comply with the datasheet Table 8 with regard to Vdiff and gain, and note the maximum possible output swing with respect to Vref. (The datasheet has formulas that will allow you to compute "exact" values for your configuration.)
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