We are currently using a Particle Photon, and have a 0 - 3.3 volt analog signal running into one of the analog input pins. This analog signal is created with a sensor and an amplification circuit consisting of a few op-amps and some passive components. When I observe the analog signal on a volt meter it is perfect and very steady. However, when I read the analog input from the Photon, I get a value ± 1200 (and remember the 10 bit ADC is 0 to 4096, so plus or minus 1200 is virtually unusable). I also experimented with taking several readings and averaging them together… its still all over the place. I also experimented with putting a 1uF capacitor across the analog input pin and ground in an attempt to smooth the signal out for the ADC, and this had no effect on the readings.
On my other projects where I have used ADC chips (I have used MCP3202 - MCP3208 chips) the analog signal would fluctuate maybe ± 10 or so… and taking averages of that works just fine and gives me a reasonable reading.
So this has me thinking that something is not right. Any help is greatly appreciated, thanks again!