How do I change the polarity of the monochrome display?

Reprogramming a display's pixel polarity is very easy with the Amulet HTML Compiler. This tip demonstrates how to invert a displays pixel polarity using the Amulet HTMLConverter.

LCD Characteristics Refresher

The Amulet HTMLCompiler has a built-in feature which allows you to program an LCD's characteristics into an Amulet starter kit, module kit or controller board. Some of the characteristics include the following:

• LCD  Width
• LCD Height
• Frame Frequency
• Pixel Clock Active Edge
• Line Pulse Polarity
• Display Polarity
• # of Data Bits

Lets say you decide to replace the existing backlit display in your Amulet starter kit with a different manufacturers display. Once you connect the new display to your Amulet starter kit and power up the kit, it looks different than before. You immediately notice the pixels that used to be dark on the old display are now light on the new display and the pixels that used to be light on the old display are dark on the new display. Hmm, what happened?

The manufacturers themselves determine the displays pixel polarity and since there really is no standard, there can be 2 possibilities. The problem occurs when a manufacturer determines whether a pixel being turned on means dark or light. One manufacturer may consider a pixel turned on as dark and another manufacturer may consider it as light.

The Example

Regardless of the display, the best thing to do is try both display pixel polarities and go with the polarity that looks best.

Step 1: From the HTMLCompiler's Settings menu, select LCD. A LCD characteristics dialog box appears upon selecting Settings -> LCD from the HTMLCompiler's menu bar.
Step 2: Depending on the display itself, fill in the LCD's characteristics accordingly. If you're not sure about any of the characteristics, then consult the general specifications of the LCD's datasheet.
Step 3: Before clicking the Program Now button, make sure the Amulet starter kit is powered and hooked up to the PC via a standard serial cable. Once the LCD characteristics are done programming into the kit and you're happy with the display pixel polarity, then that's it. If you don't like the display pixel polarity then go back and repeat steps 2 and 3, but choose the opposite display polarity.