`analogRead()` does not reset pin properly after previous `pinMode()` about arduinocore-mbed HOT 3 OPEN

Hello @dhalbert , i modified your text and it seems to be working :

void setup() 
{
Serial.begin(9600);
pinMode(A0, INPUT);
}

void loop() {
  // Attach A0 to 3.3V through a 220K or other high-value resistor,
  // so it's not stronger than the driven output.

 delay(100);
  Serial.println(analogRead(A0));



delay(100);
  Serial.println("Done");

}

the problem is still the same with touchsceen... but i'm wondering if it's not just about a pins definition problem ?

from arduinocore-mbed.

@MattGlobal In the example you gave, there is no pinMode() between analogRead() calls. In my example, the pin usage alternates between pinMode() and analogRead(). My hypothesis is that the second call to analogRead() is assuming the pin is already set up where as in fact its settings where changed "behind the back" of analogRead().

from arduinocore-mbed.

Here is the impl:

A workaround might be to call analogUpdate() before every call to analogRead(). I'll try that. (EDIT: ANALOG_CONFIG isn't defined, so analogUpdate() is not included, so it requires some surgery in the sources, which is not a clean workaround for the average user.) But there's an assumption being made in the code in this file that the pin state is not changing out from under analogRead().

from arduinocore-mbed.