LCD Display
6.4" Serial LCD
We wanted an LCD display that was large enough to display a time value visible from far away, along with the room to display the additional real-time information we would be downloading from the web. The 6.4″ Serial LCD from Sparkfun was a perfect fit. It included a backpack translator based on an ATMega168 processor, which accepted basic UART commands and translated them to the LCD’s interface. This would let us minimize the IO requirements on our microcontroller, and get the prototype up as quick as possible.
Unfortunately it would not be as easy as it seemed, we found the LCD to be riddled with bugs, and Sparkfun’s support forums agreed with these findings. Through the flow of development, we found four different critical bugs in their backpack code, causing various glitches to occur. Most involved edge cases where things were not thought out well enough to be handled properly. This often resulted in things working correct on the first pass, but once you continuously sent data for a minute, graphic glitches were bound to be seen.
Fortunately we were able to use our AVR programmer to modify the backpack’s firmware and correct all these bugs. We hope to cleanly compile them and submit the code to Sparkfun in the future, so future customers can have better luck. Maybe we’ll get a few SF beer glasses in return? 😉
Did you post the updated display backpack code anywhere? I (like everyone) had the same problems… Ended up hastily driving the display directly for a recent project. I’d love a copy of the code, though – If you’re willing to share. My serial backpack is just gathering dust at the moment.
mlaargh
2 May 10 at 5:17 pm
mlaargh,
We’d definitely like to share our fixes with the community. Right now the code has some extra things we built in to do the custom icons the average person doesn’t need. I wish we had better documented the fixes as we went along.
Here is the code we used in our final build that was the most stable: http://egaertner.com/dpac/wp-content/uploads/2010/05/backpack.c
– Eric
egaertner
2 May 10 at 5:44 pm
Awesome! Thanks so much.
mlaargh
3 May 10 at 12:30 am
Updated the code link above, it’s now better commented and has our custom extras stripped out. Should be basically what Sparkfun supplies but better.
egaertner
4 May 10 at 11:32 am