ESP8266 Community Forum

One of the things I like about Esp_Basic is that there isn't really a right way or wrong way of doing things, cos whatever works is usually just fine.
And although a biased slider certainly complicates things, you're obviously sussing things out just fine.

You could have some real fun and use the phones acellerometer to move the slider.

http://www.albertosarullo.com/demos/accelerometer/

To illustrate the novel practicality of mmiscools accelerometer idea, I have several different quadcopters that come with a phone app controller with on-screen slider joystick controls, but which also have a 'gravity' mode option.

In gravity mode the phone is inititially held flat and level but then simply tilted forward, back, left or right to control flight via the G sensor... which is intuitively easy and works surprisingly well, and with the advantage that you don't even need to be looking at the phone or fumble with its non-tactile on-screen slider components.

For your purposes you would probably create a 2-axis centre-off joystick component anyway, and you could add the gravity option to apply an off-centre bias according to the angle of the dangle!

https://youtu.be/V0SUSXCdDoA