ELM327 + ESP32 Does not load data correctly, on 16x2 LCD screen

Using Arduino Programming Questions
1

Hello, I am trying to use the ELMduino.h library to read data from the car's ECU, on a 16x2 LCD screen, but strange texts appear on the screen.

This is my code:

//Import i2C LCD libraries
#include "BluetoothSerial.h"
#include "ELMduino.h"
#include <LiquidCrystal_I2C.h>
// set the LCD number of columns and rows
int lcdColumns = 16;
int lcdRows = 2;
// set LCD address, number of columns and rows
// if you don't know your display address, run an I2C scanner sketch
LiquidCrystal_I2C lcd(0x27, lcdColumns, lcdRows);  




BluetoothSerial SerialBT;
#define ELM_PORT   SerialBT
#define DEBUG_PORT Serial


ELM327 myELM327;


uint32_t rpm = 0;


void setup()
{

#if LED_BUILTIN
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, LOW);
#endif

    // initialize LCD
  lcd.init();
  // turn on LCD backlight                      
  lcd.backlight();

  
  DEBUG_PORT.begin(115200);
  //SerialBT.setPin("1234");
  ELM_PORT.begin("ArduHUD", true);
  
  if (!ELM_PORT.connect("OBDII"))
  {
    DEBUG_PORT.println("Couldn't connect to OBD scanner - Phase 1");
    while(1);
  }

  if (!myELM327.begin(ELM_PORT, true, 2000))
  {
    Serial.println("Couldn't connect to OBD scanner - Phase 2");
    while (1);
  }

  Serial.println("Connected to ELM327");
}


void loop(){
  float tempRPM = myELM327.rpm();

  if (myELM327.nb_rx_state == ELM_SUCCESS)
  {
    rpm = (uint32_t)tempRPM;
          // set cursor to first column, first row
    lcd.setCursor(0, 0);
    lcd.print("RPM: " + rpm); Serial.println(rpm);

  }
  else if (myELM327.nb_rx_state != ELM_GETTING_MSG)
    myELM327.printError();

}

I don't know what I'm doing wrong, in the following line to load the data on the screen:

    lcd.setCursor(0, 0);
    lcd.print("RPM: " + rpm); Serial.println(rpm);

Thnks for help

2

Did you just make up this syntax and hope?

3

rpm is a uint32 & not a char or string so you get whatever random character that the binary maps to.

4

I'm new to this, little experience in programming, I assumed that if the RPMs are displayed like this in serial, the same would happen on the screen, but I'm not sure how to do it

5

Probably, but that's no reason to be unhelpful.

6

Don't ever do that when the is loads of documentation to give you the actual usage.

7

Serial.println is smart enough to know to convert a numeric and display as a string, so is lcd.print but since your starting with a string constant "RPM: " it tries to interpret rpm as a string and prints garbage.

lcd.print("RPM: " + String(rpm) );

should work better

1 Like
8

Again, snide and unhelpful.

9

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