RS485 Voting Pad System
This integrated voting system similar to audience poll system on TV game shows, Who Wants to Be a Millionaire. The keypads consist of an ATmega88 microcontroller and a MAX485/DS75176 RS-485 Transceiver. They are connected to a single RS-485 bus using daisy chain topology with CAT5 cables as connector. Keypad nodes are interfaced to the RS-485 bus using a RS-485 to TTL converter. Four push buttons are used to get the input from the audience members. To display the selected option, the keypads is equipped with LEDs.
The RS-485 network is connected to a host PC using a RS-232 to RS-485 bridge which consists of a MAX232 connected to a MAX 485/DS75176. An ATmega88 acts as the sniffer and is responsible for controlling the RX/TX enable of the RS-485 Transceiver. The RTS signal of the PC Serial port was too slow to enable or disable the TX or RX of the transceiver. For redundancy two RS-232 to RS-485 bridges can be connected to two serial ports of the PC with one operational at a time.
The front-end of the system uses of a Java application running on a PC which generates a bar graph to display voting data from audience. The microcontroller firmware is written in Embedded C language and is compiled using WinAVR. This AVR Voting Pad System is designed by Dhananjay Gadre, Sneha Lele, Anurag Chugh, And Parag Shah.
