Test + benchmark for bug #2198

check_da.ino

/*
Setup:

A0 <-> 3.3V
A9 <-> A7
A9 <-> 5
A3 -> floating

expected behavior:
digitalRead(A0) == 1
analogRead(A0) == 1023

if (digitalWrite(A9, HIGH) {
  analogRead(A7) == 1023
  digitalRead(A7) == 1
  digitalRead(5) == 1
}

if (digitalWrite(A9, LOW) {
  analogRead(A7) == 0
  digitalRead(A7) == 0
  digitalRead(5) == 0
}

analogRead(A9) ~ 400

*/

int pin_io=A9;
int pin_3v3=A0;
int pin_check_a=A7;
int pin_check_d=5;
int pin_a_spare=A3;

void setup() {
  Serial.begin(115200);
  Serial.println("Let's go benchmarking!!!");
}

int t_start, sum;

void loop() {

  t_start = millis(); 
  pinMode(pin_io, OUTPUT);
  for (int i=0; i<100000; i++)
  {
    digitalWrite(pin_io, HIGH);
  }
  Serial.print("100000 digitalWrite of the same value took ");
  Serial.println((millis()-t_start));
  
  t_start = millis(); 
  pinMode(pin_io, OUTPUT);
  for (int i=0; i<50000; i++)
  {
    digitalWrite(pin_io, HIGH);
    digitalWrite(pin_io, LOW);
  }
  Serial.print("100000 digitalWrite of the different values took ");
  Serial.println((millis()-t_start));
  
  t_start = millis(); 
  pinMode(pin_3v3, INPUT);
  for (int i=0; i<100000; i++)
  {
    analogRead(pin_3v3);
  }
  Serial.print("100000 analogRead on the same pin took ");
  Serial.println((millis()-t_start));

  t_start = millis(); 
  pinMode(pin_3v3, INPUT);
  pinMode(pin_io, INPUT);
  for (int i=0; i<50000; i++)
  {
    analogRead(pin_io);
    analogRead(pin_3v3);
  }
  Serial.print("100000 analogRead on different pins took ");
  Serial.println((millis()-t_start));

  t_start = millis();
  sum = 0;
  pinMode(pin_3v3, INPUT);
  for (int i=0; i<50000; i++)
  {
    analogRead(pin_3v3);
    sum+= digitalRead(pin_3v3);
  }
  Serial.print("100000 analogRead+digitalRead on the same pin took ");
  Serial.println((millis()-t_start));

  if (sum!=50000) {
    Serial.println("analogRead+digitalRead is broken!");
  }

  t_start = millis(); 
  sum = 0;
  pinMode(pin_check_a, INPUT);
  for (int i=0; i<50000; i++)
  {
    pinMode(pin_io, INPUT);
    analogRead(pin_io);
    pinMode(pin_io, OUTPUT);
    digitalWrite(pin_io, HIGH);
    sum+=digitalRead(pin_check_a);
  }
  Serial.print("100000 analogRead+digitalWrite (check on A pin) on the same pin took ");
  Serial.println((millis()-t_start));
  
  if (sum!=50000) {
    Serial.println("analogRead+digitalWrite is broken!");
  }
  
  t_start = millis(); 
  sum = 0;
  pinMode(pin_check_d, INPUT);
  for (int i=0; i<50000; i++)
  {
    pinMode(pin_io, INPUT);
    analogRead(pin_io);
    pinMode(pin_io, OUTPUT);
    digitalWrite(pin_io, HIGH);
    sum+=digitalRead(pin_check_d);
  }
  Serial.print("100000 analogRead+digitalWrite (check on D pin) on the same pin took ");
  Serial.println((millis()-t_start));
  
  if (sum!=50000) {
    Serial.println("analogRead+digitalWrite is broken!");
  }
  
  t_start = millis(); 
  sum = 0;
  pinMode(pin_check_d, INPUT);
  for (int i=0; i<50000; i++)
  {
    pinMode(pin_a_spare, INPUT);
    analogRead(pin_a_spare);
    pinMode(pin_io, OUTPUT);
    digitalWrite(pin_io, HIGH);
    sum+=digitalRead(pin_check_d);
  }
  Serial.print("100000 analogRead+digitalWrite (check on D pin) on different pins took ");
  Serial.println((millis()-t_start));
  
  if (sum!=50000) {
    Serial.println("analogRead+digitalWrite is broken!");
  }
}