Grade $"$C$"$

Extend Exp $1\mathrm{.}2$ to four $7-$segment display $($either $41-$digit $7-$segement, e$.$g$.$ LA$-401$EN ROHM Semiconductor $|$ Mouser Europe, or $4-$digit $7-$segment display, e$.$g$.$ LTC$-5723$HR Lite$-$On $|$ Mouser Europe$)$ where you receive a $4-$digit number from the PC using UART and show it on the display. For $"C+",$ you need to use this as a timer where you increase the count each one second.