The KTM-S1201 Serial LCD

Recently some really cheap surplus LCD modules have become available, the KTM-S1201. I purchased a few from K5BCQ, although how long they remain available is unknown. A basic spec sheet may be found here.

The KTM-S1201 has one row of 12 numeric digits. Each digit is made up of 7 segments, just like an LED. Each digit also contains a decimal point. There is no back light.

The display takes serial data from the processor. There are 6 lines, but mainly there are clock and data lines, the others being control lines. Links can be found to the uPD7225 controller spec sheets if needed.

First I tried driving the display with the segment decoder on. This worked OK, but only numeric digits (and a couple of other symbols) can be displayed, limiting the usefulness of this display.

Then I added code to drive the display with the decoder off. This lets you access each segment individually. The result is the ability to display alphabetic text, in a very crude font.

I needed to develop this code before I could design a project that used the display. My first project can be found here. (K5BCQ at the link above has a few projects available. Also N3ZI uses them in some of his kits.) 

My driver is free for anyone to use. If you improve it (or find a bug!) send me the update and I'll post it here. Keep in mind that this is hobbyist code and is provided "as is" (also note MIT license).

Update Nov. 2009: Thanks to N3ZI  for helping me get the bugs out.

Update July 2015: Thanks to NT7U for improving the initialization routine.

Download C source code for KTM-S1201 LCD driver

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