Storing and Editing Data with an SRAM

For this project, I worked in a team with two other members. We were tasked with dumping 256 values stored in a ROM component into the SRAM of a DE2 board. While there, the data could be edited by a 19-button keypad. The input of the data before reprogramming was to be displayed on the DE2 7-Segment display, displaying the address being programmed as well as the new data. Once the new data was input, the data was to be displayed on the LCD screen on the DE2. In order to take the data in from the keyboard, a cycling state machine of 125 kHz was used.

The keyboardCheck signal was sent out to power specific columns of the keyboard with a weak digital signal. The column being checked was marked with a '0'. If a key in that column was pressed during that time, the keyboard component in the system would decode the incoming signal into the binary equivalent of the letter in HEX. This signal was then sent to our SRAM controller and used for different states. For example, shift, L, and H were used to control the state of the SRAM. Shift toggled between programming and running mode. H shifted between data and address modes. L was pressed once to send the new data to the SRAM. All other keyboard inputs were simply used for data aquisition.