Re: GPIO23 and GPIO24 for RS485 Contro -- Support Forum for CompuLab's X86CORE & X86BASE Products

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Subject: Re: GPIO23 and GPIO24 for RS485 Contro

Author:
Ben Loveday

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Date Posted: 21:20:40 07/29/03 Tue
In reply to: Jorge Lemus 's message, "GPIO23 and GPIO24 for RS485 Contro" on 11:24:31 06/09/03 Mon

Hi there,

I had similar problems too. Under linux when i set the termios flags to use CRTSCTS the RTS line would not operate/toggle. I then tried to use ioctl() to set the RTS line manually (set/clear bits) and this worked although it was not very reliable, sometimes it would not clear and remain high and the timing was not always that accurate, although i found how to fix that. In the end i used a 555 timer circuit which is triggered off the TX line (TTL) and sets the RTS for a set time, enough for the data to be sent.
This has worked quite well although it would be nice to get the proper RTS toggle working! Hope this helps. Let me know if you work it out!

Cheers,
Ben

>Hi
>
>I have been trying to control COM4 rs485 driver using
>GPIO24 in accordance to 686 Base schematic. I have not
> be able to do it in spite the use of code examples
>that I found in the compulab web site (sio.c).
>
>I check the 83627 SIO data sheet from windbond I it
>looks that every thing that I didi is right. More
>over, I was able to change the IRQs for COM2 and COM4
>of 686Base wich are controled for the same chip.
>
>Have some of you some idea of what I am doing wrong
>
>Thanks and best regrads to all of you
>
>Jorge Lemus

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