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RSS moving Display using ARM Cortex- M3 (LPC 1768)


This is a report concerning the revival of an old 5x7led 24 digit message display board,where the controls are removed and the display functionality is completely absorbed by the Mbed module.
With the new controller extra features are possible like internet connectivity. This enables us to add RSSdisplay functionality and set the real time clock by a time server. It is also possible to “twitter” messages to the message board. This all should be worked out in short time, because the contest is shutting down end February.

Goal: To make an old message display working again with the new Mbed module. Goal is to replace all functionality by the Mbed. Extra feature is to add internet connectivity and display RSS messages generated by websites or an own database RSSfeed generator.

From a colleague I got an old message display with 24 5x7led digits. In first instance I wanted to use it for my work. On the search of the brand of the display there raised the problem that it was a custom made industrial display board without any references to the type or model. The only indication on the display PCB’s was the marking code DL21004. The control board had marking sign: DATA DISPLAY SHIP SM1 D97 7So the software was not available anymore and I didn’t want to ask around and begging for the software which was probably from the last century. After opening the cover, it turned out that the design of the display was from 1995 and had an old fashioned controller board. Microprocessor, EPROM chip, Ram chip, real time clock with gold cap it was all provided as separate chips. This was the moment I thought that it would be nice to give the message board a new life with Mbed. Removing the old hardware control board, and replacing it by the Mbed module would be a nice challenge to work on. Also adding an internet connection would be great. With that and using a time server for time setting and RSSfeed reading these were nice possibilities.

I was hoping to reach in a few days the point that I could start writing software to control the display. My first attempt was very hope full, I tried to display  234567890AB on one of the two cascaded PCB display. The result wasn’t what I hoped for, but it was stable and I could understand what was wrong.
The character table codes were already found on the internet, I found some projects where the whole character table was available, so why invent the wheel again, copy and paste….

Visually you could see that the picture is upside down, and row 1 and 7 were mixed. It took 5 minutes to find the problem and fix it with the right software control. I had a timing problem with row 7 and 1, and I reversed the row counting sequence.
After this I tried to see the time real time counting on the display. For that I used the real time clock on the Mbed and I tried to display it. This took not a long time, but already I started to think on a way how to synchronize the clock time. With the helpful Mbed website it took not very long to use an internet connection with a time server.

*Source : NXP Design Challenge (For Educational Use only)


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