Here is the set of variables related to the LCD, the backlight and contrast values are important. ‘printname’ is not here for the LCD, it actually is used when returning strings over the serial port. ‘transmit’ is what I use to send commands to the LCD.
//LCD stuff
int back_val = 255;
int cont_val = 90;
String transmit = “”;
String printname = “”;
This is my initializer for the LCD (the LCD is on Serial3), it sets the contrast and backlight value to the values in memory (could use the command bytes) so that whatever state the LCD is in, it gets set up right.
void LCD_init()
{
Serial3.begin(115200);
LCD_clear();transmit = “CONTRAST;”;
transmit += cont_val;
Serial3.println(transmit);transmit = “BACKLIGHT;”;
transmit += back_val;
Serial3.println(transmit);
}
These are the commands to display things on the LCD manually (like using the Serial print and println commands). These are used internal to the code all the time, there are wrappers though that let them get used by the serial port commands.
void LCD_displn(String prints,int line)//displays on a given line, does not emulate CR LF
{
transmit = “DISPLN;”;
transmit += line;
transmit += “;”;
transmit += prints;
Serial3.println(transmit);
}
void LCD_disp(String prints)
{
transmit = “DISP;”;
transmit += prints;
Serial3.println(transmit);
}
These set the backlight and contrast from the serial console on the OpenAccess
// sets contrast
//format: CONTRAST;<analog value, 0-255 or nothing for default>
void SCmd_contrast()
{transmit = “CONTRAST;”;
char *arg;
//Serial.println(“contrast”);
arg = SCmd.next();
if (arg != NULL)
{
transmit += arg;
}
else
{
transmit += cont_val;
}
Serial3.println(transmit);
}
// sets backlight
//format: BACKLIGHT;<analog value, 0-255 or nothing for default>
void SCmd_backlight()
{transmit = “BACKLIGHT;”;
char *arg;
//Serial.println(“backlight”);
arg = SCmd.next();
if (arg != NULL)
{
transmit += arg;
}
else
{
transmit += back_val;
}
Serial3.println(transmit);
}
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This is my clear command (it is a 2 line LCD) This is modular so you can fill in your own code to clear whatever display you use:
inline void LCD_clear()
{
LCD_displn(” “,0);
LCD_displn(” “,1);
}
This is how you can manually overwrite the display from the console:
// uses display
//format: DISP;<0=line 1, 1=line 2 (or no argument to clear the display)>;<string (or no argument to clear the line)>
void SCmd_display()
{
char *arg;
arg = SCmd.next();
if (arg != NULL)
{
if (atoi(arg) == 0)
{
arg = SCmd.next();
if (arg != NULL)
{
LCD_displn(arg,0);
}
else
{
LCD_displn(” “,0);
}
}
else if (atoi(arg) == 1)
{
arg = SCmd.next();
if (arg != NULL)
{
LCD_displn(arg,1);
}
else
{
LCD_displn(” “,1);
}
}
}
else
{
LCD_clear();
}
}
This runs every loop that nothing interesting is happening and chooses the splash screen:
void LCD_default()
{
LCD_clear();
if(doorbell)
{
LCD_displn(“Welcome: press “,0);
LCD_displn(“”#” to enter “,1);
}
else if(doorhold)
{
LCD_displn(“Door held: press”,0);
LCD_displn(“”#” to enter “,1);
}
else
{
LCD_displn(“i3 Detroit “,0);
LCD_displn(“Hackerspace “,1);
}
}
That’s my LCD functions, you can see that I compartmentalized it a lot so it is easy to change the protocol or library of your display. This is part of the greater OpenAccess project.
