2008-12-06 20:24:11     Reading from ttyS0

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2008-12-06 20:24:11     Reading from ttyS0

andy (UNITED STATES)

Message: 66463   

 

Am receving data on serial pin rx0. when I do a cat of ttyS0 I can see the data. But when I try to open the file and read from it, read is returning -1 always. It is supposed to return 1 which is the number of bytes I am reading from ttyS0.

I am unable to figure out what the problem could be.

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2008-12-06 20:59:29     Re: Reading from ttyS0

andy (UNITED STATES)

Message: 66464   

 

ok am able to open ttyS0 using fopen and read using fgetc. but when i use open and read system calls it does not work. Not sure why this is happening.

 

 

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2008-12-06 22:15:32     Re: Reading from ttyS0

Mike Frysinger (UNITED STATES)

Message: 66465   

 

if you open the device in non-blocking mode, then it'll return -1 immediately if there is no data to read

 

review the errno value to see why read() is returning early, or run i through strace

 

that said, why are you reading ttyS0 ?  are you sure that's what you want ?  the Blackfin UART is ttyBF#, not ttyS#.

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2008-12-06 22:55:41     Re: Reading from ttyS0

andy (UNITED STATES)

Message: 66466   

 

I dont see any ttyBFx files in /dev. There is only ttyS0 and ttyS1. Also when I do a cat on ttyS0 I can see the data coming in.

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2008-12-07 00:49:14     Re: Reading from ttyS0

Mike Frysinger (UNITED STATES)

Message: 66467   

 

you should be using the latest release 2008R1.5

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2008-12-07 16:51:07     Re: Reading from ttyS0

andy (UNITED STATES)

Message: 66479   

 

Am using an old verion 2006R2. Am able to read from ttyS0 by doing fgetc. but fputc seems to be failing. am unable to write to ttyS0 now. fputc and fprintf always return -1??

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2008-12-07 17:08:29     Re: Reading from ttyS0

Mike Frysinger (UNITED STATES)

Message: 66480   

 

there have been many fixes in the serial code since 2006R2

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