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

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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   

 

try removing TLSBIT from the TCR register then ?

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2010-08-23 03:51:20     Re: Stamp BF537, SPORT1 RS485

Julien Vermillard (FRANCE)

Message: 92685   

 

no sucess

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2010-08-23 03:57:37     Re: Stamp BF537, SPORT1 RS485

Mike Frysinger (UNITED STATES)

Message: 92686   

 

ok, but is that the same as "no difference in signal output" ?

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2010-08-23 04:27:58     Re: Stamp BF537, SPORT1 RS485

Sonic Zhang (CHINA)

Message: 92687   

 

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.

 

---

 

I guess you mean

 

RED is DTxPRI

 

BLUE is TFSx

 

I don't see error on your picture. The SPORT UART driver shifts LSB first, which works well with UART protocol.

 

Do you receive data over RS485 in MSB mode? If so, you should change the TLSBIT as well in the current driver.

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