ESP8266 Community Forum

Posted: **Sat Oct 01, 2016 7:31 pm**

My current project involves adding WIFI to a current device. The device in question has 20 LED status lights and I want to display them on a webpage for remote viewing (within wifi range). The part I'm stuck at is interfacing to the current device.

This device uses 3 74HC595 shift registers to drive the 20 LEDs. I could add three 74HC165s to the ESP to read the status of the LEDs but a much cleaner interface would be to read the serial data going to the cascading 595s and set variables in the ESP to be used in the web server.

Has anyone done this or know of similar code I could start with, I'm rather basic with my programming skills so I will not be able to write this code from scratch but could modify code written for a similar application. It's really only the serial input I need help with.

Posted: **Tue Oct 04, 2016 3:47 pm**

So I was able to read in the serial data using the following script. I don't understand how its syncing with the serial data without the latch/load signal but it is in fact working.

Now to set the ESP to AP and create a web server................

Code: Select all

//**************************************************************//
//  Name    : Read 3 Bytes from Level Master outputs            //
//  Author  :                                                   //
//  Date    : Oct 3, 2016                                       //
//  Version : 1.0                                               //
//  Notes   : Reading as inputs the output to 3 74HC595's       //
//          :                                                   //
//****************************************************************

//define where your pins are
// int latchPin = D7; //Latch/load signal does not appear to be needed
int dataPin = D6;
int clockPin = D5;

//Define variables to hold the data 
//for each shift register.
byte switchVar1 = 0;  
byte switchVar2 = 0; 
byte switchVar3 = 0; 

void setup() {
  //start serial
  Serial.begin(115200);

  //define pin modes
//  pinMode(latchPin, INPUT_PULLUP); //Latch/load signal does not appear to be needed
  pinMode(clockPin, INPUT_PULLUP); 
  pinMode(dataPin, INPUT_PULLUP);


void loop() {
  
  //collect each shift register into a byte
  //the register attached to the chip comes in first 
  switchVar1 = shiftIn(dataPin, clockPin);
  switchVar2 = shiftIn(dataPin, clockPin);
  switchVar3 = shiftIn(dataPin, clockPin);

  //Print out the results.
  //leading 0's at the top of the byte 
  //(7, 6, 5, etc) will be dropped before 
  //the first pin that has a high input
  //reading  
  Serial.print("Byte 1: ");
  Serial.println(switchVar1, BIN);
  Serial.print("Byte 2: ");
  Serial.println(switchVar2, BIN);
  Serial.print("Byte 3: ");
  Serial.println(switchVar3, BIN);

//white space
Serial.println("-------------------");
//delay so all these print satements can keep up. 
delay(500);
ledStatus();
}

//------------------------------------------------end main loop

////// ----------------------------------------shiftIn function
///// just needs the location of the data pin and the clock pin
///// it returns a byte with each bit in the byte corresponding
///// to a pin on the shift register. leftBit 7 = Pin 7 / Bit 0= Pin 0

byte shiftIn(int myDataPin, int myClockPin) { 
  int i;
  int temp = 0;
  int pinState;
  byte myDataIn = 0;

  pinMode(myClockPin, INPUT_PULLUP);
  pinMode(myDataPin, INPUT_PULLUP);

//The register transmits the information about the pins from pin 7 to pin 0
//so that is why our function counts down
  for (i=7; i>=0; i--)
  {
    while(digitalRead(myClockPin) == LOW) {}           //Wait for input to go high again
    while(digitalRead(myClockPin) == HIGH) {} 
    delayMicroseconds(2);
    temp = !digitalRead(myDataPin);
//    }
    if (temp) {
      pinState = 1;
      //set the bit to 0 no matter what
      myDataIn = myDataIn | (1 << i);
    }
    else {
      //turn it off -- only necessary for debuging
     //print statement since myDataIn starts as 0
      pinState = 0;
    }

    //Debuging print statements
    //Serial.print(pinState);
    //Serial.print("     ");
    //Serial.println (dataIn, BIN);

  }
  //debuging print statements whitespace
  //Serial.println();
  //Serial.println(myDataIn, BIN);
  return myDataIn;
}


void ledStatus() {

  if( bitRead(switchVar1, 0) )
  Serial.println("LED 1");
  if( bitRead(switchVar1, 1) )
  Serial.println("LED 2");
  if( bitRead(switchVar1, 2) )
  Serial.println("LED 3");
  if( bitRead(switchVar1, 3) )
  Serial.println("LED 4");
  if( bitRead(switchVar1, 4) )
  Serial.println("LED 5");
  if( bitRead(switchVar1, 5) )
  Serial.println("LED 6");
  if( bitRead(switchVar1, 6) )
  Serial.println("LED 7");
  if( bitRead(switchVar1, 7) )
  Serial.println("LED 8");
  if( bitRead(switchVar2, 0) )
  Serial.println("LED 9");
  if( bitRead(switchVar2, 1) )
  Serial.println("LED 10");
  if( bitRead(switchVar2, 2) )
  Serial.println("LED 11");
  if( bitRead(switchVar2, 3) )
  Serial.println("LED 12");
  if( bitRead(switchVar2, 4) )
  Serial.println("LED 13");
  if( bitRead(switchVar2, 5) )
  Serial.println("LED 14");
  if( bitRead(switchVar2, 6) )
  Serial.println("LED 15");
  if( bitRead(switchVar2, 7) )
  Serial.println("LED 16");
  if( bitRead(switchVar2, 0) )
  Serial.println("LED 17");
  if( bitRead(switchVar3, 1) )
  Serial.println("LED 18");
  if( bitRead(switchVar3, 2) )
  Serial.println("LED 19");
  if( bitRead(switchVar3, 3) )
  Serial.println("LED 20");
  if( bitRead(switchVar3, 4) )
  Serial.println("LED 21");
  if( bitRead(switchVar3, 5) )
  Serial.println("LED 22");
  if( bitRead(switchVar3, 6) )
  Serial.println("LED 23");
  if( bitRead(switchVar3, 7) )
  Serial.println("LED 24");
}

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