LCD or a Liquid Crystal Display is almost seen everywhere ranging from digital watches to microwave ovens, from audio systems to PDA’s and even some high-end servers. First, there is the low-level timing on the parallel port, second is the execution time needed for various commands especially if you’re not using busy-flag checking. So here’s a translation table:. The configure script detects if you have the required include files, and deactivates ppdev if they are not there. The size of the displays is given with “Size1”, “Size2”, “Size3” and “Size4” and are automatically evaluated to form “Size”, so you can omit it, too. Now for the wiring details in 8-bit mode:

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But, what if you want a faster mechanism to display and want to do away with all this socket thing.

Displaying Real Time System information on a LCD Display using LCDproc & lcdmod LG #76

The driver knows of two ways of controlling the parallel port: The displays are connected to the parallel board see Wiring belowand are quite timing-critical. Note that under normal circumstances you won’t need such a section, lcd4linux uses default values which should work with most displays. That’s what the Timing section in the lcd4linux.

If your Display or your interface provides a way to control the backlight by software, LCD4Linux supports this, too. The old, ugly and unportable raw programming of ports, and the new, cool, great ppdev style.

This has been done in a delay loop, which had to be calibrated. LCDs are manufactured by quite a few different companies.


To make it easier to play with the timing values, I invented a fuzz factor, which modifies all other timing values. DB3 on the display are not used. Before you attempt to wire up the display with your computer remember that you have to be pretty cautious with what you do here otherwise you can damage either the display pinux your computer, so linuxx you are not aware of assembling simple electronic circuits, don’t get disheartened.

The driver supports different models of the HD, which can be selected with the ‘Model’ parameter: The HD is probably the most common display driver. The driver fully supports the text, bar and icon widgets.

CONFIG_HD44780: HD44780 Character LCD support

This feature is available in V0. LCD or a Liquid Crystal Display is almost seen everywhere ranging from digital watches to microwave ovens, from audio systems to PDA’s and even some high-end servers. The initial backlight level my be specified with the Brightness parameter in the Display section. You can connect up to 8 digital output lines to the parallel port with a simple additional circuit e. The “RS” signal has to be connected to one of the bd44780 data lines DB I have personally tried out Hitachi HD compatible 16X2 LCD display which are easily available from many display linnux and can be controlled through the parallel port.

There are several cheap commercially available displays which can be controlled through the computer’s parallel port hd4470 the serial port RS You can modify this default delay of msec with the Timing. Calibration is no longer necessary! If you are using devfs or udev, these devices may become visible as soon as you load the ppdev kernel module.


You have to specify this signal with the Wire. Please do note that some displays come with an option of backlight and others don’t, the ones with a backlight option have some more pins to control the backlight and are bit more expensive, so the choice is yours!!

Add HD44780 Character LCD support

So here’s a translation table: Lknux the time you’ve installed and configured LCDProc you must have realized that this software is actually based on a client-server model. If you want to try so, you have to specify this signal with the Wire.

But this did not always work, some displays really need smaller values Powered by Trac 1. Let’s get going through the installation, i’ve assumed that you have your lcd display properly wired up and tested with LCDProc. A HDDisplay usually has 16 Pins if you find only 14, there’s no backlight, so pin 15 and 16 are missing.

You need an additional hd44780 signal from the parallel port. The second, third and fourth “Enable” for displays with two controllers or multiple displays signal has to be connected to one of the control signals.