This project was my final team project for "Electrical Engineering Laboratory 3" class in 2004 (when I was junior in college). The goal was to make a wireless system that substitutes price tags with electrical displays in grocery stores. The base station manages a list of products in the database, and it sends out price information to receiver units. Receiver units are simple character displays having unique IDs. When any products' prices change, the system can easily update new prices on these displays.
In order to implement this system, ARM7 board was used as a base unit that manages a database and transmits price information. RF hardware modules were used for the wireless communication. Receiver units were implemented using 8051 boards. I implemented the LCD control modules for ARM7 (dot LCD display) and 8051 (character LCD display), and a physical-layer wireless communication module for RF chipsets using C language (firmware).
After the class, I re-implemented the base unit using MFC instead of ARM7 board, so that we can manage the database using MS Access on a desktop computer. Then, my colleagues and I started up a student-venture company called U-Mind Inc. in 2004 with this system. But it lasted only for five months due to the investment issue.