Array from digital reads of 16 inputs

Projects General Guidance
1

I am attempting to combine the state of 8 digital inputs into a single value.

Pin Number State
1 0 //LSB
2 1
3 1
4 1
5 1
6 1
7 1
8 1 //MSB

I will be sending this out over modbus as Binary 11111110 or Decimal 2046 or Hexidecimal FE

How do I convert the digital inputs into a single value? Can I just create an Array from a bunch of digital reads?

2

Familiarize yourself with the available functions.
https://www.arduino.cc/reference/en/language/functions/bits-and-bytes/bitset/

3

Welcome to the forum

Read the values and use bitSet() to set the appropriate bits of a byte variable

If you are using a Uno or similar Arduin then note that using pins 0 and 1 is not advisable dues to them being used by the Serial interface

4

Thanks for the quick response. I will give this a try. I just needed a jumping off point for my coding.
Have a great holiday.

5

Pin 1 is often reserved for serial communication.
Maybe better to use another pin...

6

Probably a few ways to do it... here's a couple.

uint8_t values[8] = {0,1,1,1,1,1,1,1};  // LSB first
byte data1, data2;

void setup()
{
  Serial.begin(115200);

  for (uint8_t x = 0; x < 8; x++)
  {
    if (values[x] == 1)
    {
      bitSet(data1, x);
      data2 = data2 | (1 << x); 
    }
  }

  Serial.println(data1, HEX);
  Serial.println(data2, HEX);
}

void loop()
{}

... and yeah... don't use pins 0 & 1.

7

@JeromeJordan note that what you need to create is not an array nor has it got 16 bits despite the topic title

8

Instead of creating an array from the inputs and then putting the values together, you can get the data directly from the pins.

const uint8_t pinList[8] = {2, 3, 5, 4, A0, A1, A2, A3};  // LSB first
byte data;

void setup()
{
  Serial.begin(115200);

  for (size_t i = 0; i < 8; i++)
  {
    pinMode(pinList[i], INPUT_PULLUP);
  }

  data = 0;
  for (uint8_t i = 0; i < 8; i++)
  {
    if (digitalRead(pinList[i]) == HIGH)
    {
      bitSet(data, i);
    }
  }

  Serial.println(data, HEX);
}

void loop() {}
1 Like
9

I've been contemplating an API that would read or write "all the pins" (or at least D0-D13) into a single call. It would default to multiple digitalRead() and ORing into a uint16, but could be customized to be much faster (two port reads on Uno)

1 Like
10

The Mega has a port with consecutively mapped pins, on the end connector. So you can read all of those pins in one line of code.

11

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