Differnce between UART and RS232

[testbenchmark]

Hello everyone,

I'am designing a model rocket flight computer. This is a two stage rocket so that's mean I will use two flight computer.

Flight computers should have a communication between themselfs. For this communication which one is better?

Directly connect two UART's of MCU's each other or UART-RS232 converter circuit ?

I will use only RX-TX-GND pin in RS232 connection. 

a visualization for better understanding...

Thank you!

[Tesla DeLorean]

Use a Common Ground in both cases.

CMOS to CMOS levels on a pair of relatively closely coupled boards should be just fine.

You could use some series resistors to limit current.

For longer cables, and entirely different computers / power systems, RS232 to RS232 levels might be a better choice

[testbenchmark]

I have 1.5 meters distance between two flight computer. 

I'll take your point about “Use Common Ground in both cases.” 

I will use RS232 for common ground in communication and noise reduction. 

Thanks...

[Pavel A.]

RS-232 is a protocol. UART is a device.

[Techn]

The difference is that when you connect TTL to TTL, its operating at 3.3 Volt digital, there are possibility of wrong data due to noise. For reliability use TTL(3.3V) to UART level shifter at both ends. Check if there is any difference in Ground potential between both boards using a mutimeter.

[unsigned_char_array · Accepted solution]

UART is the peripheral that can output asynchronous serial data frames like for RS232.

RS232 is a communication standard that includes voltage levels and connector descriptions in addition to description of the serial data frames. RS232 has more signals than just RX and TX.

For communication I prefer RS485 over RS232 since you can connect more than 2 devices (multidrop) and you achieve higher bitrates. The downside is you need a bias network and termination and you can only send half duplex.