Measure and display voltage on I2C LCD

Forum 2005-2010 (read only) Hardware Interfacing
1

I am frustrated that I can't read/display a dc voltage on Analog Pin 0.

Any idea where am going wrong? The LCD displays text as expected - just cant seem to display voltage.

 #include <WString.h>
#include <Wire.h>

int inputVoltagePin = 0; //int batt volts = input pin 0;

int lcd = 40;
void lcd2s_init()
{
delay(300);

Wire.beginTransmission (lcd); // transmit to device 0x50
Wire.send (0x8C); // send lcd clear command
Wire.endTransmission (); // stop transmitting
delay(500);

Wire.beginTransmission (lcd); // transmit to device 0x50
Wire.send (0x28); // turn B/light ON
Wire.endTransmission (); // stop transmitting
delay(300);
}
void setup ()

{
Wire.begin();
lcd2s_init();

Wire.beginTransmission(lcd); // transmit to device 0x50
Wire.send (0x80); // ready to move cursor to location given by next byte
Wire.send ("Battery Volts =\n");//dispaly volts on next line
Wire.endTransmission(); // stop transmitting

}

void loop ()
{
  delay(300);
  
   // read voltage value
  int voltage = analogRead(inputVoltagePin);
  int valueVolts=voltage;
  
Wire.beginTransmission(lcd); // transmit to device 0x50
Wire.send (valueVolts);
Wire.endTransmission(); // stop transmitting

delay (6000);

Wire.beginTransmission(lcd); // transmit to device 0x50
Wire.send (0x20);//backlight off
Wire.endTransmission(); // stop transmitting
}
2

Do you need to convert your reading to ASCII?
("itoa()")
[edit]The "send(int)" method in "Wire" simply casts the supplied "int" to "uint8_t" and call the "send(uint8_t)" method, which is not what you want.[/edit]

3

Thanks for the reply. I sort of understand. I need to convert the ADC value to ASCII and send that to the LCD. If only I knew how?

Using itoa and or float statements have got me lost. Any suggestions of sample code? I'm sure reading the ADC and displaying the results via I2C as a voltage has been done before.

4

Did you ever figure this out? If you did, could you post the code for it? Thanks.