Build yourself a wirelessly controlled, Arduino-powered message board!
Here's an easy project which creates a wirelessly programmable message board. It uses XBee modules to provide a wireless serial link between your computer and the device. You interact with it via a simple menu system. There are no buttons (other than the reset button, which is hidden) on the device.
Step 1: What's It All About
The Arduino has three types of memory: flash, EEPROM and RAM. In this project, we use all three to store messages and values. Since we can't change the flash from inside the program, we use it to store 'canned' messages, or messages that don't change. We keep these short so they fit right on the display. We can also use the RAM to store a message, but we don't have much, so we keep that short too. The internal EEPROM is only 512 bytes, but that's enough to store a program of which canned messages to display and for how long. Finally, we add an external serial EEPROM, in which we store a long message (up to the whole size of the EEPROM) that we scroll across the display.
The following programming concepts are demonstrated:
- creating a simple menu system using the serial interface
- accepting and validating strings and integers via the serial interface
- retrieving strings from flash memory using progmem
- storing and retrieving strings in external EEPROM using a simple data structure
- storing configuration data in the onboard EEPROM
- displaying static and scrolling text on a parallel interface LCD (or LCD compatible display)
- measuring an analog value, in this case light levels