UART serial Flow Control

Help with Raspberry Pi Foundation Boards (Raspberry Pi, Pi Zero, Pi Zero W, Pi A, Pi B, Pi B+, Pi2 B, Pi3 B, Pi 3 B+)
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N5BOC
Posts: 1
Joined: Sat Apr 14, 2018 5:49 am

UART serial Flow Control

Post by N5BOC » Fri Jul 26, 2019 1:31 am

I have read where you can enable FLOW CONTROL on the pi UART by assigning some GPIO pins to it. Now I realize the MMDVM's don't make use of Flow Control, but I just wonder if by chance it is active on the serial UART when operating in Pi Star. I'm wanting to glue an FPGA in between the PI and the MMDVM to see if I can implement some type of buffer so that no bits are lost.

Thanks so much.
Dave
N5BOC

KE7FNS
Posts: 495
Joined: Wed Apr 17, 2019 11:11 pm

Re: UART serial Flow Control

Post by KE7FNS » Fri Jul 26, 2019 3:46 am

N5BOC wrote:
Fri Jul 26, 2019 1:31 am
I have read where you can enable FLOW CONTROL on the pi UART by assigning some GPIO pins to it. Now I realize the MMDVM's don't make use of Flow Control, but I just wonder if by chance it is active on the serial UART when operating in Pi Star.
No, its not active on a RPi, and its not active on MMDVM's that use a STM32 processor either. In order to make it active, you'd have to enable it on both sides, in the RPi, and on the MMDVM firmware. Its possible, but its a waste of time and effort.
N5BOC wrote:
Fri Jul 26, 2019 1:31 am
I'm wanting to glue an FPGA in between the PI and the MMDVM to see if I can implement some type of buffer so that no bits are lost.
There are NO bits being lost, if there were bits being lost things wouldn't work correctly. Messages between the RPi and the MMDVM would be corrupted left and right, and that just isn't the case.

Adding another link in the chain of communications is just going to add a delay. If you are going to bother putting a FPGA in there, you might as well just have it do all processing that the STM32 does.
All views, comments, posts and opinions shared are entirely my own.

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