Hi,
For your problem, you need to implement the UART in its entirety, the use of just Rx, Tx and GND is a simplified version of it. UART solves your problem by design, I can help you with that
I am an Electronics and computer science engineer, I have experience working with various protocols, prototyping boards, Raspberry Pi, Arduino, mbed (ARM proto board)... as well as developing custom PCBs, you can find some of my projects on my portfolio.
I pride myself on ensuring that the customer is satisfied with the quality of the work and strive to sustain good communication and complete the project (5-star reviews/ 100% completion rate)
Also, for what it is worth, I'm a preferred freelancer on this platform
Looking forward to working with you.
Regards,
Nabil