Changing my ESP devices to use numbers instead of Home Assistant input numbers and buttons instead of switches that turn themselves off after a delay is on my 3 page list of things to do.
EDIT: ok that’s one thing off my list. First post updated to use ESP template number.
I had the same problem with my mattress which is a memory foam type. I believe the problem is that the weigh distribution of the mattress is fairly even across the entire bed frame so it doesn’t particularly distribute weight to the sensor.
I solve it by raising the force sensor off the slats. I use a piece of wood, about 0.5 inch high, 1 inch in width and 60 cm or more to have the entire strip on. This basically allows more pressure to be exerted on the strip and thereby dropping the resistance of the sensor to measurable range. Even with this trick, the resistance is still fairly high so the voltage chagne between occupy and empty is about 1V but accurate enough for me.
Can the ESP32 be powered by USB power? I have hooked everything up and voltage never drops when sensor is pressed. I have confirmed my sensor is working and not damaged.
The 0.L signal indicates the resistance is greater than your meter can read (overload), likely greater than >20 megaohms. I installed a 1 megaohm resistor in parallel with my fsr so that I always have a reading that is manageable for me.
Thanks @tom_l for this awesome project! I’m currently running an ESP32 (2 FSR) and a D1 Mini (3 FSR) very smoothly!
I followed your tutorial but I just noticed one thing: during my initial test, I had a regular voltage when I did not touch the FSR, like 3.15V constantly (which is also seems to be the case for other in this thread).
However, after investing why I had some weird binary sensor presence (I use an input_number in helper instead inside the ESP code), I found that voltage fluctuates from 2.8V to 3.16V.
I use a single 100k for the 3 FSR on D1 Mini (for my son) and 2 x 300k for the 2 FSR on the ESP (master bedroom). I tried without the mattress, keeping only 1 FSR or changing the resistance but the voltage still fluctuates.
In attachment the graph over a 2h windows.
Is voltage supposed to fluctuate that much, or should it be stable? Any ideas?
Thanks!
If Rin = Rout, fair to say that I’m in trouble with the FSR as is?
We have a king size mattress on top of two box springs, and then the wood slats are under both, so I’m (somewhat unsurprisingly) not getting a resistance differential between in and out. They’re both about 110 K-ohms. Thinking about grabbing a spare strip of 1x2 or 1x3 and slipping it under the mattress and above the box spring.
@tom_l, when measuring Rin and Rout, obviously the circuit should not be powered, but…is it important to have all the connections in place (other than power) in order to accurately gauge resistance? My leads are quite long, which would theoretically increase ohm value.