I have been using the capacitance break out board in a project I am working on (single touch pad). It has been working well for some time. Recently it seems to want to stick in the high state (most but not all of the time) and the only way to get to to go low is to disconnect the 3.3V power.
Any idea what might cause this problem?
Given the problem showed up w/the trick of powering it from a DIO pin, I have to believe they’re related. The DIO pin might have 10-20 ohms equivalent output impedance, perhaps a current draw spike is somehow hanging up the cap sensor board.
https://www.sparkfun.com/products/12041
Then again the board has a 0.1 uF cap on it’s Vcc.
Now the board problem show up whether or not I use the DIO pin. It isn’t 100% of the time but enough that it is not acceptable. I ahve a spare that I will try tonight.
Are you running into this ???
3.3 Max On-duration
If an object or material obstructs the sense pad the signal may rise enough to create a detection, preventing further operation. To prevent this, the sensor includes a timer which monitors detections. If a detection exceeds the timer setting the sensor performs a full recalibration. This is known as the Max On-duration feature and is set to ~60s (at 3V in LP mode). This will vary slightly with Cs and if SYNC mode is used. As the internal timebase for Max Onduration is determined by the burst rate, the use of SYNC can cause dramatic changes in this parameter depending on the SYNC pulse spacing. For example, at 60Hz SYNC mode the Max On-duration will be ~6s at 3V.