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
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Joined: Sat Apr 14, 2018 5:49 am

UART serial Flow Control

Post by N5BOC »

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
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KE7FNS
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Re: UART serial Flow Control

Post by KE7FNS »

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.
If someones previous actions are any indication of their future actions, then I predict the deletion and removal of access will happen at any moment. 7-11-2020.

"07/13/20 This Website Has Been Taken Down" ... again :lol:
N5BOC
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Re: UART serial Flow Control

Post by N5BOC »

You are right. Offloading the work done by the STM32 into an FPGA would be the correct thing to do instead of gluing something in between them.
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MW0MWZ
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Re: UART serial Flow Control

Post by MW0MWZ »

I don't believe that bits are lots between the Pi and the modem (be it USB or UART GPIO pins).
the BER or Loss that we see can be either decode issues, or network issues, is this what you were looking to fix ?
Andy

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