The microcontroller that will control the environmental sensing module is the cyclone II field programmable gate array. Some of the important features provided by the cyclone II are its high density architecture with up to 35,000 logic elements, up to 1.1 Mbits of RAM, true duel port operation, embedded multipliers and advanced I/O support. The Synchronous Dynamic RAM (SDRAM) is controlled by a single 3.3 volt power supply which means it could be used as a separate component and not change our voltage regulator. The SDRAM is a high speed 67 Mbit random access memory that can be clocked at frequencies up to 133 MHz. The DM9000A Ethernet connection is a low pin count single chip fast Ethernet controller with a general processor interface. It is designed to operate at 3.3 volts like all the other components and is fully compliant with the IEEE 802.3u standard. The DM9000A also utilizes an auto-negotiation function which will automatically configure the connection to take the maximum advantage of its abilities. The JTAG UART core implements a method to communicate between a host PC and an SOPC builder system loaded into the Cyclone II FPGA. This allows the host PC to connect via alternate cables such as the USB-Blaster. The JTAG circuitry is already built into Altera FPGAs, and software support is provided by Altera. Device drivers are provided in the hardware abstraction layer system library; this allows access to the JTAG UART core using the ANSI C Standard Library stdio.h routines. The ISP 1362 is a Universal Serial Bus (USB) controller; it complies fully with USB specification rev. 2.0, supports data transfer at speeds up to 12 Mbit/s, and also operates at 3.3 volts. The general purpose input/output (GPIO) is handled by the expansion headers on the Altera DE2 board. Each header can provide either 5 or 3.3 volts and has two separate pins for ground. The DE2 board has two expansion headers.
The Altera DE2 board was selected as the center for the environmental sensing module because it contained these six essential components. Obviously if we were to try to take the environmental sensing module to production we would get each of the components above separately due to size constraints and the many unused features of the Altera DE2 board.