Display Subsystem

[kd1889]

• [x] turn on and turn off the display
• [x] send data to the display
• [x] check to see if display shows correct output

[kd1889]

Added new functions/globals to support sending data to screen. The globals included pins and their connections to the LCD screen, as shown in radio.py. The following functions were added to support send_data_to_screen from prior lab exercises: char_to_arr(c), converts a character to a list of binary that represents the ASCII value. write_arr_4bits(bits, mode), takes a bit array and mode (command or characters) for the LCD. Writes the four most significant bits, and then the four least significant bits sequentially. setup_LCD(), sets up the LCD screen display to four bit mode. The demo.py was updated for the send_data_to_screen(text) section to better represent the functionality of the code. The toggle_display(state) function was updated to turn on/off the text on the screen.