Arduino Liquid Crystal Display not printing - arduino

I am attempting to use the liquid crystal display of an Arduino Uno for a school project. I followed the instructions on https://www.arduino.cc/en/Tutorial/HelloWorld exactly as it is stated and it does not print the text.
The backlight is functioning properly and the contrast is adjusting with the potentiometer, but no text comes out.
#include <LiquidCrystal.h>
// initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
void setup() {
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// Print a message to the LCD.
lcd.print("hello, world!");
}
void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print(millis() / 1000);
}
`

Judging by the image you linked it looks like the display isn't properly connected: you should solder a pin header to it first.
See the part near the red arrow: https://i.imgur.com/eSOMe1x.jpg

Related

Arduino Uno stepper direction

I am having trouble getting a stepper motor to rotate counterclockwise with code written for an Arduino Uno.
This is a simple setup that uses a push button to move the stepper as you hold the button.
Originally the code was written to move the stepper clockwise and I changed the myStepMotor.step to have a -1 instead of 1. From my understanding this should cause the stepper to go in the other direction, but with both a positive or negative number it still rotates in the clockwise direction.
#include <Stepper.h>
const int myStepsPerRev = 64;
char k_ccw;
int myStepsTook = 0;
// allocate a stepper motor object for pins 8 through 11:
Stepper myStepMotor (myStepsPerRev, 8, 9, 10, 11);
void setup() {
pinMode(3, INPUT);
myStepMotor.setSpeed(60); // set the motor speed for 60rpm
myStepsTook = 0; // initialize steps taken to zero
Serial.begin(9600); // initialize the serial port
}
void loop() {
k_ccw = digitalRead(3);
if (k_ccw == LOW) {
delay(125);
myStepsTook++;
Serial.print("Steps Taken: ");
Serial.println(myStepsTook);
myStepMotor.step(-1);
}
}
The pin sequence you want is a bit unexpected; if you connected it in the "standard" way, the 28BYJ-48 should be initialised in software like so:
Stepper myStepMotor(myStepsPerRev, 8, 10, 9, 11);
It should then work properly in both directions.
See here for more information, should you need it.

When programming an Arduino in C, how do we write two characters next to each other?

I have the following code for my arduino, however the adafruit lcd display only prints the down arrow character and not the up arrow then the down arrow. (the loop function is empty so I didn't include it).
#include <Wire.h>
#include <Adafruit_RGBLCDShield.h>
#include <utility/Adafruit_MCP23017.h>
Adafruit_RGBLCDShield lcd = Adafruit_RGBLCDShield();
#define UP_ARROW 0
byte up[] = {4, 14, 31, 4, 4, 4, 0, 0};
#define DOWN_ARROW 1
byte down[] = {0, 0, 4, 4, 4, 31, 14, 4};
void setup() {
lcd.clear();
lcd.begin(16,2);
lcd.setCursor(0,0);
lcd.createChar(UP_ARROW, up);
lcd.write(UP_ARROW);
lcd.setCursor(1,0);
lcd.createChar(DOWN_ARROW, down);
lcd.write(DOWN_ARROW);
}
Based on your library's source code,
void Adafruit_RGBLCDShield::createChar(uint8_t location, uint8_t charmap[]) {
location &= 0x7; // we only have 8 locations 0-7
command(LCD_SETCGRAMADDR | (location << 3));
for (int i=0; i<8; i++) {
write(charmap[i]);
}
command(LCD_SETDDRAMADDR); // unfortunately resets the location to 0,0
}
If I were you I would create the characters at the start of the program, then position the cursor and write them as needed.
From the Arduino reference:
NB : When referencing custom character "0", if it is not in a variable, you need to cast it as a byte, otherwise the compiler throws an error. See the example below.
In your example, UP_ARROW will be replaced be 0 in lcd.write(UP_ARROW);
Maybe try: lcd.write(byte(UP_ARROW));
Hope it helps.
Turns out my problem is that creating a character resets the cursor position to (0,0), so when I set the cursor to (0,1) and create the down arrow, it resets the cursor to (0,0). My solution was to create the custom characters first and then set the cursor and write them.

LCD not giving desired output

I am learning Arduino and I was making one program which will print "Hello" to the lcd display connected to arduino.
I dont know what is wrong but the LCD is not showing desired output, rather shows special characters and when I increase/decrease the contrast of lcd using the Potentiometer, the characters changes everytime.
my code is:
// include the library code:
#include <LiquidCrystal.h>
// initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
void setup() {
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// Print a message to the LCD.
lcd.print("hello");
}
void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print(millis() / 1000);
}
Please help.
Check what kind of lcd you are using.
Some lcd's come with the pin numbering reversed. IE the location of the 16 pins is on the top left corner, but instead of starting with pin number 1, the lcd starts with pin number 16.
Since the format of the LCD pins is the same both way (GND, VCC, input * 14, vcc, Gnd) it does not cause shorting problems, But the control signals are sent to the data pins, and the data signals are sent to the control pins.
I got this hint from the fact that changing the brightness changes the characters. If I am right, changing the contrast via the potentiometer will do you no good with respect to the actual contrast.

Need help displaying serial monitor on LCD

I'm having issues displaying the serial monitor on an lcd. I am not getting any error and the LCD is lit up so I don't think I wired it wrong. I am able to open up the serial monitor/plotter and see in information changing so my other component is also working so the problem must be in the code...
#include <LiquidCrystal.h>
/**
* LIDARLite I2C Example
* Author: Garmin
* Modified by: Shawn Hymel (SparkFun Electronics)
* Date: June 29, 2017
*
* Read distance from LIDAR-Lite v3 over I2C
*
* See the Operation Manual for wiring diagrams and more information:
* http://static.garmin.com/pumac/LIDAR_Lite_v3_Operation_Manual_and_Technical_Specifications.pdf
*/
#include <Wire.h>
#include <LIDARLite.h>
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
// Globals
LIDARLite lidarLite;
int cal_cnt = 0;
void setup()
{
Serial.begin(9600); // Initialize serial connection to display distance readings
lidarLite.begin(0, true); // Set configuration to default and I2C to 400 kHz
lidarLite.configure(0); // Change this number to try out alternate configurations
lcd.begin(16, 2);
// initialize the serial communications:
}
void loop()
{
int dist;
// At the beginning of every 100 readings,
// take a measurement with receiver bias correction
if ( cal_cnt == 0 ) {
dist = lidarLite.distance(); // With bias correction
} else {
dist = lidarLite.distance(false); // Without bias correction
}
// Increment reading counter
cal_cnt++;
cal_cnt = cal_cnt % 100;
// Display distance
Serial.print(dist);
Serial.println(" cm");
delay(10);
// when characters arrive over the serial port...
if (Serial.available()) {
// wait a bit for the entire message to arrive
delay(100);
// clear the screen
lcd.clear();
// read all the available characters
while (Serial.available() > 0) {
// display each character to the LCD
lcd.write(Serial.read());
}
}
}
The LCD should be displaying the changing measurements
The LCD is lit up and I can adjust the back light but I can't get anything to show up.
Just because the LCD is "lit" doesn't mean it's wired correctly. In fact, the backlighting circuit is usually totally separate from the data and control signals circuits. I would start by checking the assumption that it's wired correctly with a simple command to print a known value to the LCD:
lcd.clear();
lcd.println("TEST");
If this works, then you know the LCD is working and can look elsewhere for the problem.
If this doesn't work, I'd question your assumption that it's hooked up correctly, but if you still get nothing but "blue blocks" then it might be something as simple as your contrast is not correct. It can be tricky getting the contrast and brightness to a good combination for readability. See if your display has a small potentiometer (usually adjustable with a very small Philips-head driver) on the back and carefully adjust the contrast.
Brightness is often changeable through software commands but most LCDs default to high brightness when first booted up.
If changing contrast doesn't work, you may have a real wiring problem and then it really is off-topic for this forum. In that case you should sketch a schematic and post on Electrical Engineering stack.

Arduino code combination - combine temp sensor and buzzer at max min temp codes

I love this site. Thank you all for what you do here!
I am finally getting into doing my own projects with Arduino Uno. I find I learn best when I just do it. I found a tutorial on getting temperature from my TMP36GZ to read out on my 16x2 LCD via Ardino. Way cool! But now, I want to figure out how to make a CEM1203(42) buzzer go off when the temperature hits a maximum and/or minimum. I found a simple code to get the buzzer to go too. Now I just need to combine the two.
Below are the 2 codes. I would like to, say, have the buzzer sound when temp is =/<65°F and =/>75°F.
Thank you for any help you can offer. I'm very excited to be learning this stuff!
/*
Piezo
This example shows how to run a Piezo Buzzer on pin 9
using the analogWrite() function.
It beeps 3 times fast at startup, waits a second then beeps continuously
at a slower pace
*/
void setup() {
// declare pin 9 to be an output:
pinMode(9, OUTPUT);
beep(50);
beep(50);
beep(50);
delay(1000);
}
void loop() {
beep(200);
}
void beep(unsigned char delayms){
analogWrite(9, 20); // Almost any value can be used except 0 and 255
// experiment to get the best tone
delay(delayms); // wait for a delayms ms
analogWrite(9, 0); // 0 turns it off
delay(delayms); // wait for a delayms ms
}
/*
September 12 2013
October 25 2012
Based off of a project by DJ Mentzik.
Enhanced and modified by WWC and citin.
Supporting documents can be found at http://www.instructables.com/member/WWC/
Use and modife as needed.
Displays Current, 8 sec Average, Max and Min Temperature.
To wire your LCD screen to your Arduino, connect the following pins:
LCD Pin 6 to digital pin 12
LCD Pin 4 to digital pin 11
LCD Pin 11 to digital pin 5
LCD Pin 12 to digital pin 4
LCD Pin 13 to digital pin 3
LCD Pin 14 to digital pin 2
LCD PIN 15 to POS
LCD PIN 16 to GND
*/
#include <LiquidCrystal.h> // include the LCD driver library
//declare variables
float tempC = 0; // Variable for holding Celcius temp (floating for decimal points precision)
float tempf = 0; // variable for holding Fareghneit temp
int tempPin = 0; // Declaring the Analog input to be 0 (A0) of Arduino board.
float samples[8]; // Array to hold 8 samples for Average temp calculation
float maxi = 0,mini = 100; // Max/Min temperature variables with initial values. LM35 in simple setup only measures Temp above 0.
int i;
LiquidCrystal lcd(12, 11, 5, 4, 3, 2); // initialize the library with the numbers of the interface pins
void setup()
{
Serial.begin(9600); // Opens serial port, sets data rate to 9600 bps
lcd.begin(16, 2); // Set up the LCD's number of columns and rows:
lcd.setCursor(2, 0); // Set LCD cursor position (column, row)
lcd.print("Waynes World"); // Print text to LCD
lcd.setCursor(3, 1); // Set LCD cursor position (column,row)
lcd.print("Thermometer"); // Print text to LCD
delay(5000); // wait 500ms // Delay to read text
lcd.clear(); // clear LCD display // Clear the display
lcd.setCursor(2, 0); // Set LCD cursor position (column, row)
lcd.print("LCD Displayed"); // Print text to LCD
lcd.setCursor(1, 1); // Set LCD cursor position (column, row)
lcd.print(" Averaged Temp "); // Print text to LCD
delay(5000); // Delay to read text
lcd.clear(); // Clear LCD
}
void loop()
{
Serial.println(""); // Blank line for spacing in the serial monitor
Serial.println("You are looking at a project built by WWC."); // Print text to Serial monitor
Serial.print("Feal free to use and modife as needed.");
Serial.println(""); // Blank line for spacing in the serial monitor
Serial.print("LM35 Raw data: "); // Print text to Serial monitor
Serial.println(analogRead(tempPin)); // Displays on serial monitor the sampled value before conversion to real Temperature reading
// Start of calculations FOR loop.
for(i = 0;i<=7;i++){ // gets 8 samples of temperature
samples[i] = ( 4.4 * analogRead(tempPin) * 26) / 1024.0; // conversion math of tmp36GZ sample to readable temperature and stores result to samples array.
Serial.println(samples[i]); // Print samples [i] to sertiual monitor
// ( LCD note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 0); // Set LCD cursor position (column 0, row 0)
lcd.print("Current Temp is: "); // Print text to LCD
lcd.setCursor(1, 1); // Set LCD cursor position (column 1, row 1)
lcd.print(" Celcius "); // Print text to LCD
lcd.setCursor(12, 1); // Set LCD cursor position (column 12, row 1)
lcd.print(samples[i]); // print current Temp sample to LCD
tempC = tempC + samples[i]; // do the addition for average temperature
delay(800); // wait 800ms
} // END of FOR loop
Serial.println(""); // Blank line for spacing in the serial monitor
Serial.println(""); // Blank line for spacing in the serial monitor
tempC = tempC/8.0; // calculated the averare of 8 samples in Celcius
tempf = (tempC * 9)/ 5 + 32; // converts to fahrenheit
if(tempC > maxi) {maxi = tempC;} // set max temperature
if(tempC < mini) {mini = tempC;} // set min temperature
if(tempC >16.0)
// Send Results to Serial Monitor
Serial.println("New measurement:");
Serial.print(" Average Temperature in Celcius is " ); // Print text to Serial monitor
Serial.println(tempC);//send the data to the computer // Send the data to the computer
Serial.print(" Average Temperature in Farenait is " ); // Print text to Serial monitor
Serial.println(tempf);//send the data to the computer // Send the data to the computer
Serial.print(" MAX Temperature in Celcius is " ); // Print text to Serial monitor
Serial.println(maxi);//send the data to the computer // Send the data to the computer
Serial.print(" MIN Temperature in Celcius is " ); // Print text to Serial monitor
Serial.println(mini);//send the data to the computer // Send the data to the computer
// Send results to LCD.
lcd.setCursor(0, 1); // Set LCD cursor position (column 0, line 1)
lcd.print(" Fahrenheit "); // Print text to LCD
lcd.setCursor(12, 1); // Set LCD cursor position (column 12, line 1)
lcd.print(tempf); // Send the data to the LCD
delay(6000); // Wait 3 seconds to display the Fahrenheit temp and 3 seconds to display results to LCD screen befor starting the loop again = 6 seconds.
tempC = 0; // Set tempC to 0 so calculations can be done again
}
Your temperature code has the most in it so put the additions in there.
Usually you would transfer all from setup. In this case:
pinMode(9, OUTPUT);
is the only required code. You can put in the rest if you want it to beep on startup.
Transfer over the entire "void beep()" function. So you can call it the same way it is called in the "void loop()" function.
Then in your temp code after tempf is calculated in the line:
tempf = (tempC * 9)/ 5 + 32;
Put some code like:
if (tempf <= 65){
//low temp beep code here
}
else if (tempf >= 75) {
//high temp beep code here
}

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