DPAC

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? 😉