Using connection mode 1:

This approach uses a single connectivity line that supports a combined data and clock signal between the microcontroller and the LCD display. This approach is used when the LCD is connected through a shift register 74HC595, as detailed at here. This connection method is also called a 1-wire connection.

This solution approach recognises the original work provided in the Elektor Magazine.

Relevant Constants:

Specific constants are used to control settings for the Liquid Crystal Display routines included with Great Cow BASIC. To set these constants the main program should specific constants to support the connection mode using #define.

When using connection mode 1, only two constants must be set - all others are optional or can be ignored.

How to connect and control the LCD background led: see LCDBacklight.

Constant Name Controls Default Value


The I/O mode.



The clock/data pin used in 1-bit mode.


LCD.h supports in 1-wire mode the control of pin 4 of the 74HC595 for the background led.

For a code example download One Wire LCD Example.

See for further code examples see 0,1 and 2 Wire LCD Solutions.

See the separate sections of the Help file for the specifics of each Connection Mode.

For more help, see LCD_IO 0, LCD_IO 2 LCD_IO 2_74xx164, LCD_IO 2_74xx174 LCD_IO 4, LCD_IO 8, LCD_IO 10 or LCD_IO 12