Spark Fun serial LCD back light controlls.

Serial Enabled 16x2 LCD - White on Black 3.3V
sku: LCD-09067

Arduino MEGA 2560 R3

I am quite new at this, but been reading and searching quite a bit to avoid asking frivolous questions, but I need some advice.

I have this display working using this code:

#include <SoftwareSerial.h>

SoftwareSerial mySerial(9, 10); // mySerial(rx, tx);

void setup()


void loop()

mySerial.print(" Hello dave");
mySerial.print(" Got the serial");
mySerial.print(" working ");


And I find this in the files associated with the serial controller for the LCD:

brightness_setting = letter & 0b.0001.1111; //Brightness is a value from 0-29 only (5-bit)
onboard_eewrite(brightness_setting, LCD_BRIGHTNESS_SETTING); //Record to EEPROM

along with Quite a few other similar lines pertaining to brightness controll.
according to the spark fun spec sheet on the 16f688, it requires a command :

by sending special command character 0x7C (decimal 124) followed by a number 128-157, the backlight PWM will be set.

So, my question is what does that look like on the scetch pad? I have tries several combinations of these commands and “|” characters follower by numbers and nothing works. I think i am missunderstanding the spec sheets due to my lack of knowlage so advice would be greatly apriciated!

mySerial.write(0x7C); mySerial.write(0x80);This should set the.back light to some brightness.

liudr: mySerial.write(0x7C); mySerial.write(0x80);This should set the.back light to some brightness.

that sequence will set the brightness to zero!

0x7C 0x80 // brightness off 0x7C 0x8C // 40% 0x7C 0x96 // 73% 0x7C 0x9D // 100%

other values in between to set different levels

here are some more commands that you might find useful

0xFE    254         
        0x80    address cursor position

0x7C    124         
        1       backlight on
        2       backlight off
        3       set 20 chars per line
        4       set 16 chars per line
        5       set 4 lines
        6       set 2 lines
        7       set 1 line
        8       init LCD
        9       toggle splash
        10      set splash
        11      set 2400 baud
        12      set 4800 baud
        13      set 9600 baud
        14      set 14400 baud
        15      set 19200 baud
        16      set 38400 baud

0x08    8           backspace

0x12    18          set 9600 baud if received during splash

Thanks, got it 8)