2010-08-19 10:03:48 Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92584

Hi,

I'm trying to use RS485 over the SPORT1, the trasmit/receive mode is supposed to be driven by the TRS pin of the sport.

When I write data to /dev/ttySS1, the TRS isn't really looking like a "transmit enable". Is it supposed to work "out of the box" ? or I need to modify the driver ?

Thanks,

Julien

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2010-08-19 10:20:28 Stamp BF537, SPORT1 RS485

Michael Hennerich (GERMANY)

Message: 92586 I used this driver in for RS485 purposes before -

But I think you need some pull-up resistors.

Try to search the forums - I think you should find some information.

-Michael

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2010-08-19 11:44:58 Re: Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92589

I verified all my pull-up/pull-down it's looking fine.

Here a capture of what I have : people.apache.org/~jvermillard/rs485.png

BLUE is data out

RED is TRS supposed to be barred DE.

Why when not transmitting it's not back to receiving ?

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2010-08-19 12:41:04 Re: Stamp BF537, SPORT1 RS485

Michael Hennerich (GERMANY)

Message: 92592 What kernel version are you using?

I think I fixed this 16 months ago -

blackfin.uclinux.org/gf/project/linux-kernel/scmsvn/?action=browse&path=%2F&view=rev&revision=6209

-Michael

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2010-08-19 13:08:58 Re: Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92593

My revision :

URL: svn://blackfin.uclinux.org/linux-kernel/trunk/drivers/serial

Repository Root: svn://blackfin.uclinux.org/linux-kernel

Repository UUID: 526b6c2d-f592-4532-a319-5dd88ccb003d

Revision: 8602

Node Kind: directory

Schedule: normal

Last Changed Author: bhsong

Last Changed Rev: 8528

Last Changed Date: 2010-03-22 10:37:11 +0100 (Mon, 22 Mar 2010)

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2010-08-19 13:33:09 Re: Stamp BF537, SPORT1 RS485

Michael Hennerich (GERMANY)

Message: 92594 Looking at trunk head - someone reverted this fix.

Can you try with the TCR1 settings from my patch?

-Michael

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2010-08-19 13:40:24 Re: Stamp BF537, SPORT1 RS485

Mike Frysinger (UNITED STATES)

Message: 92595

svn rev 6782 by Sonic ...

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2010-08-20 04:01:51 Re: Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92618

Thanks, now the signal looks much better.

I plugged a RS485/232 converter and I receive, but only wrong chars. The baud rate settings was fubared too ?

I'm going to test withanother converter before pugging a logic analyzer.

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2010-08-20 04:32:47 Re: Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92620 The bit lengths are 17,62µs which is corresponding to 57600, I don't understand why my console is scrambled. This was tested recently ? �W=;'5�= ��QҪڿ!3�ysm�9/- ��Ӆ! � = - -!#� = -#1�#! �= =-'=;'5�� %= �3'= /��;!! '!=75 �#! ��'-# �)5'��#! ��'-# �)5'��#! ��3��e}y�}77 5 �#! ��i*� -�;3-#� -��{'=9)3-#�!#�9/- �Y_m�y!# !''5 �w - 5 ��S5 -!#�� 51 A;= 5339��7%=�9/=##5'��i

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2010-08-20 06:18:59 Re: Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92623

I changed my serial port parameters like that : stty -F /dev/ttySS1 ispeed 57600 ospeed 57600 cs8 -icrnl -ixon igncr -opost -onlcr -isig -icanon -iexten -echo -echoe -echoke -hupcl -echoctl min 1 time 0

I just do a echo " " > /dev/ttySS1

Here the scope capture :

people.apache.org/~jvermillard/capture4.png

BLUE is DTxPRI

RED is TFSx

well if you count bits it's wrong, it's in revert order and inverted.

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2010-08-20 08:08:18 Re: Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92628

Here my modified setup in function sport_uart_setup(...) :

SPORT_PUT_TCR1(up, (LATFS | ITFS | TLSBIT | ITCLK));

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2010-08-20 08:15:55 Re: Stamp BF537, SPORT1 RS485

Michael Hennerich (GERMANY)

Message: 92629 Do you still think the bits are shifted out in reversed order?

If yes - I think Sonic needs to take a look -

He's done most of the rework recently.

-Michael

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2010-08-20 08:29:08 Re: Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92631

Yes,

for example transmitting 'U' works. U is 0x555 so 01010101 is binary

So if you revert the order you have : 10101010 and you do the 1 complement you are back to 0x55 so 'U'.

If you try to transmit something else you have weird chars. I'm not sure but I think there is a problem on the stop bit too.

If it was modified recently I'm curious to know if it was tested. I never digged in SPORT configuration and I'm pretty new to DSP so debugging that myself will be pretty tedious.

Thanks for your support,

Julien

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2010-08-20 10:28:11 Re: Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92641

I plugged a logic analyzer in UART mode, configured for 57600, it's see corretly the start bit but then the data are wrongs.

I start to think something is really broken in the driver.

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2010-08-20 12:39:28 Re: Stamp BF537, SPORT1 RS485

Mike Frysinger (UNITED STATES)

Message: 92645