2010-08-15 07:16:04     Why is u-boot's serial port so slow?

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2010-08-15 07:16:04     Why is u-boot's serial port so slow?

Patrick Doyle (UNITED STATES)

Message: 92423   


...and is there anything I can do about it?


I realize that the generally accepted method around here for tranfsering images to a uClinux based board is via the ethernet, but I am supporting (remotely) a customer who has a lot of Windows experience and very little Linux experience.  Consequently, I would like to avoid the complications of "Go out and set up a Linux server; now get tftp running on it; now hook it up to your board.  Do you have a crossover cable?  Well, if you hook it into your switch, you're going to have to figure out the IP address of your linux server; etc..."


I thought it would be simpler to just say "Fire up a Hyperterminal; type these commands; use Z-modem to download this file I gave you; and use these commands to save it to the flash."


However, when trying that at my end, I find that it takes over an hour(*) to download the 3.8MByte uImage file from the distribution.  (Yes, I know I can trim the size of that back, and I will, but not just yet.)


Is there something wrong with my hardware (either on my host side, or on the side of the BF518 board) that it should take so long?


Is there something wrong with my math: 57,600 baud -> round to 50,000 bits/sec -> round to 5000 bytes/sec.  3.8Mbyte / 5000 bytes/sec = 760 seconds.  I think this download should take 10 to 15 minutes, not over an hour!


Any thoughts?



(*) Actually, I have yet to be able to successfully download the entire image -- it has always failed somewhere in the first megabyte or so.  Also, in the spirit of full disclosure, I am using minicom on a MacBook connected to the target via a cheap Radio Shack USB/Serial adapter cable.  I'd be thrilled to hear somebody say "No, this works at full speed for me" and realize that it's a hardware setup issue on my end.


In the mean time, I'm going to go investigate what it will take to get the hardwired ethernet port on my MacBook to show up as an ethernet interface inside my VMWare Ubuntu box and just go with TFTP.






2010-08-15 10:28:55     Why is u-boot's serial port so slow?

Javier Herrero (SPAIN)

Message: 92425    > (enter your response here)




2010-08-15 13:28:02     Re: Why is u-boot's serial port so slow?

Mike Frysinger (UNITED STATES)

Message: 92427   


sounds like your USB dongle is a piece of ****.  i get full speed (ignoring protocol overhead) using a USB dongle that isnt crappy.


generally, ones using the PL2303 chip are good.




2010-08-15 19:39:22     Re: Why is u-boot's serial port so slow?

Patrick Doyle (UNITED STATES)

Message: 92428   


OK, that's all I wanted to know.  Thanks.