UART CTS and RTS missing on UART 1, 2,

In fairness to this vendor - multiple ARM MCU vendors (also) "skimp" on, "Full UART Port Implementations."

If such "UART extras" are required there (still) exist dedicated, multi-UART chips - which include such capability...

And they are usually left off because they are simple to implement in software. In fact most UARTs that provide CTS/RTS/DTR etc... only provide status flags. Any reaction to the inputs or setting of the outputs is left to the application.

Robert

Does this mean I could use UART without official RTS CTS by plugging them on normal GPIO ?

The device I plan to plug are L70 from quectel, M35/M95 from quectel too.

And - do you expect your "helpers" to search/find and then comb those specs, too?

I don't expect so, but as I see some are qualified as Guru in the forum, in case they would have already experienced similar situation and would like to share their solutions, I would be happy to save hours or day of search leveraging their guruness and experience :)

You'll fare (far better) by "linking" to your unique device data - not expecting (even exalted gurus) to make that (extra/unwanted) effort for you!

Hello Chrischina,

I suspect that some level of handshaking capability should be able to be implemented using GPIOs/software to implement the CTS/RTS functionality; however, I don't have a lot of experience with full UART implementations since I normally have only utilized simple SCI based communications.

That's the normal method

Robert

Thank you Chuck and Robert for your answers.
What about doing this: drawing my schematic connecting RTS and CTS to some normakl GPIO in prevention that I may need it. I prototype my board and later on if I found out that I need to implement it then I will bit banged those signal on GPIO. Is it something doable ?

Hello Crischina,

This sounds like the path of least risk unless you need those GPIOs for other functions. If you do this, you may consider the use of 0Ohm resistors to make the HW connection optional during manufacturing. This way you don't run the risk of some extraneous signals on these GPIOS in the case they aren't used for CTS/RTS.

You may also consider checking about the other devices to see if they have a mode where the CTS/RTS are not needed ahead of drawing up your schematic but this leaves the risk of some small/remote need that was not considered.

I agree with Chuck. I'd only add that you should also include pull-up/ pull-dn on your module's inputs. They should be there in an y case but particularly if there is a chance they will end up unconnected. I'd also route the signals to a header for easy re-use/probing.

Robert

Thank you both again for your answers. I will do accordingly

Search the Bookshelf tag, I left a reference to an introductory book to serial/uart programming under that tag.

Robert