Custom-Character Calculator

Alphanumeric LCDs have eight custom characters that can be defined by loading bitmaps into the module's character-generator RAM (CG-RAM). Our BPK-000 interface, and BPK-, BPI- and ILM-series modules all allow you to define custom characters.

Although it's relatively easy to calculate custom-character bitmap values by hand, it can be tedious if you have more than a few bitmaps to work out (as in our rolling odometer app note). This app note presents a visual bitmap calculator that lets you draw a character, then copy and paste the list of bitmap values into your own program. It's written in Javascript, so it should run on any modern browser. If it doesn't run, you may have Javascript disabled in your preferences.

Check out customer-written bitmap calculators for Windows PCs.

Bitmap Calculator

Click the pixels to toggle them on/off. When you've got the pattern you want, copy the list of values into your program. Follow the instructions in your display manual to download the data to the desired custom-character position.

List of bitmap values:

 

Final Notes

Bitmap values generated with this calculator can be used with any standard alphanumeric LCD--even those that are connected without the benefit of a serial interface.

You may have noticed that the initial value for each bitmap (all pixels off) is 128 (10000000 binary) instead of 0. The three highest bits in each byte are unused and ignored by the LCD, so they can be 0 or 1 without affecting the appearance of the bitmap. We're setting one of these bits to 1 to avoid causing problems with programming languages and interfaces that discard any byte containing all 0s (ASCII null).

This program is © Scott Edwards Electronics, Inc., June 1999. It is free for your personal, non-commercial use. Any other use requires our express prior permission.

"Portable" Version for Windows

Seetron customer Rick Szczesniak, rpsez@mediaone.net, has written a bitmap calculator that can be used without a web browser. It runs under current versions of the Windows operating system. Click here to download.

Please address any queries regarding this software to Rick. He'd also appreciate hearing about your serial-LCD applications; email rpsez@mediaone.net.

Alphanumeric and SGX-120L Character Editors

Steven M., Perceptor15@aol.com, offers two different character editors--one for alphanumeric LCDs, the other for our SGX-120L serial graphics LCD. Note that the latter requires the MSCOMM32.OCX to operate. Click here to download.