Seetron Tech: GLO-416Y Big-Font Modes

A prospective customer requested more info on the differences between the big-font modes of the BPP-420L and the GLO-416Y. It's a good question, because the two are fundamentally different, and because it's an excellent opportunity to highlight the many improved features of the GLO-series serial OLEDs.

BPP-420L Serial LCD

The BPP-420L is a text-mode LCD with a 9600bps serial interface. We rolled it out in the late 1990s, and its large-character mode was novel at the time. The large characters are made by defining wedge and block shapes with the LCD's custom characters and arranging them in 4-by-4-character mosaics as shown in the examples below. The process is transparent to the user--when the display is in "big" mode it automatically generates large characters for the letters A-Z (uppercase only), numbers 0-9, and a few punctuation symbols (period, colon, hyphen).

BPP-420L Big Text

BPP-420L Big Numbers

There are several limitations to this method of generating large characters.

Text LCDs have physical gaps between characters which cause the 'plaid' look of the tile-built big characters.
Since the big characters are built using the LCD's custom character set, custom characters are not available for other uses.
The character set is limited to only those symbols that can be legibly drawn with crude, block graphics.
The full 4-line screen height is required to draw the characters; there are no 2-line-tall characters.
With only four character positions, it's not possible to show, for example, the time in 12:34 format.

GLO-416Y Serial OLED

When suitable OLED modules became available, we took the opportunity to design out the limitations of the previous LCD modules. The serial interface of our GLO-series displays contains its own bitmapped fonts and custom-character RAM, and can display characters in six sizes. (See the programmer's reference for details.) The font sizes can be freely mixed and matched on the screen, and they don't cut into the custom-character capability. In fact, user-defined characters can also be displayed at any size, and there are double the number of custom-characters available compared to LCDs (16 vs 8).

In addition, the GLOs can store custom characters and a user-defined splash screen in nonvolatile memory so that the display is ready to go the instant power is applied. The display has numerous other advantages like high contrast, low power consumption, much better operation at extremes of temperature...but since the question was specifically about the large font sizes, here's a little photo album. Other examples are here and here.