Q: I have problem loading u-boot with UART, what does a successful "loading u-boot over uart" looks like?
A: Take BF537 ezkit for example, a successful loading u-boot via UART looks like following, similar for other CPU/boards.
1)swtich boot mode to 7
2)power on the board
3)press the reset button
4)run "bfin-uclinux-ldr -l u-boot-bf537-stamp-uart-2012R2-RC3.ldr /dev/ttyUSB1"
Note if you get fail, you may try repeating combination step 3) and 4) a couple of times.
And the result is:
bfin-uclinux-ldr -l u-boot-bf537-stamp-uart-2012R2-RC3.ldr /dev/ttyUSB1
Loading LDR u-boot-bf537-stamp-uart-2012R2-RC3.ldr ... OK!
Removing stale lock '//var/lock/LCK..ttyUSB1'
Opening /dev/ttyUSB1 ... OK!
Configuring terminal I/O ... OK!
Trying to send autobaud ... OK!
Trying to read autobaud ... bfin-uclinux-ldr: received signal 14: timeout while sending; aborting
root@aaron-desktop:/home/aaron/temp# bfin-uclinux-ldr -l u-boot-bf537-stamp-uart-2012R2-RC3.ldr /dev/ttyUSB1
Trying to read autobaud ... OK!
Checking autobaud ... OK!
Autobaud result: 115200bps 49.766mhz (header:0xBF DLL:0x1B DLH:0x00 fin:0x00)
Sending blocks of DXE 1 ... [17/17] (100%)[board said:
See, it's really easy, I am not encountering fails and do not have to try multiple times to get this success. the line:
Sending blocks of DXE 1 ... [17/17] (100%)
indicates the download progress and may last for dozens of seconds.
after this 100% progress, will see some information like:
OK!
You may want to run minicom or kermit now
So far the file u-boot-bf537-stamp-uart-2012R2-RC3.ldr has been downloaded to RAM of the board and in running with a serial console of 57600-8-N-1. Open a minicom with 57600-8-N-1, type any key on the keyboard, I am getting the u-boot console like this:
bfin> version
U-Boot 2012.07-rc2 (ADI-2012R2) (Jan 07 2013 - 16:25:40)
bfin-uclinux-gcc (ADI-2012R2-RC2) 4.3.5
GNU ld (ADI-2012R2-RC2) 2.21
bfin>
And at the bottom of ubuntu minicom window I see information like this, indicating the current minicom setting is 57600 8N1
If you have problems, check the trouble shooting: http://docs.blackfin.uclinux.org/doku.php?id=bootloaders:u-boot:loading#troubleshooting