T02 - LED display driver

4-digit LED display is connected to microcontroler by the use of two serial-in shift registers with output latches SN74LS595. To display any information on the display it is necessary to send two bytes:

• 1st byte represents individual segments of single LED display (D7..D0)
• 2nd byte represents address of digit (A7..A0)

Used pins of microcontroller:

• GPIOA9 - serial data
• GPIOA8 - clock
• GPIOB5 - latch

Figure 1 shows time diagram of communication between microcontroller and LED display. Bits are sent starting from MSB.

Example of serial data sequence (two bytes) to show number 0 on 1st digit (from the left): 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1