2009-04-19 05:51:45     uart problem of bf561

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2009-04-19 05:51:45     uart problem of bf561

bin zhang (CHINA)

Message: 72821   

 

Hi;

 

      We just let  the TX RX pin of  uart hang in the air, and choose the silent uboot mode because we don‘t need any print info to the console. But when i tun on the power,uboot  doesn't work.......I don't know what the problem is. Could you give me some advice?

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2009-04-19 07:13:48     Re: uart problem of bf561

Martin Strubel (SWITZERLAND)

Message: 72822   

 

Hi,

 

 

 

floating RX is considered 'forbidden' :-)

 

You should use a pullup (22k is ok). The problem is, when the Bfin sees a Low when the UART is armed, it will possibly throw framing errors and cause an exception. This is why u-boot might get stuck. You could hack u-boot to ignore this, but I wouldn't recommend that.

 

Greetings,

 

- Martin

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2009-04-19 22:02:48     Re: uart problem of bf561

bin zhang (CHINA)

Message: 72828   

 

Hi,Martin,

 

     Could you please tell me how to hack u-boot to ignore that or which file to be corrected??

 

-Bin

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2009-04-20 04:33:18     Re: uart problem of bf561

Martin Strubel (SWITZERLAND)

Message: 72849   

 

Hi Bin,

 

sorry, I don't know which specific file to touch, I'd have to look up myself and am a little in a hurry. What you'll have to look for is the SIC_IMASK register to mask out the UART error interrupt. I'd expecct this somewhere in the UART initialization code. I assume you can not access that pin?

 

Wishing success,

 

- Martin

 

 

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2009-04-20 08:08:18     Re: uart problem of bf561

Robin Getz (UNITED STATES)

Message: 72869   

 

Bin:

 

You said:

 

> We just let  the TX RX pin of  uart hang in the air

 

Do you mean the TX/RX pins of the RS-232 charge pump? or the TX/RX pins of the Blackfin?

 

-Robin

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2009-04-20 10:03:00     Re: uart problem of bf561

Mike Frysinger (UNITED STATES)

Message: 72881   

 

u-boot doesnt use interrupts at all, and none of the SIC_* registers should ever be touched directly under Linux

 

what you want to do is not supported ... so if your UART isnt usable, dont use/enable the driver

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