Specifications

14.2.15. Why do I get TFTP timeouts?
Question 1:: When trying to download a file from the TFTP server I always get timeouts like these:
...
Loading: #######T ##################################T###################T ####T ##T #
###T #T #########T ########T #############T ##T #############T ########T #############T
#####T ###T ######T #######T #######T #############T ##T ##############T ###########
###########
done
If the target is connected directly to the host PC (i. e. without a switch inbetween) the problem goes away or is
at least less incisive.
What's wrong?
Answer 1:: Most probably you have a full duplex/half duplex problem. Verify that U-Boot is setting the
ethernet interface on your board to the proper duplex mode (full/half). I'm guessing your board is half duplex
but your switch is full (typical of a switch ;-).
The switch sends traffic to your board while your board is transmitting... that is a collision (late collision at
that) to your board but is OK to the switch. This doesn't happen nearly as much with a direct link to your PC
since then you have a dedicated link without much asynchronous traffic.
The software (U-Boot/Linux) needs to poll the PHY chip for duplex mode and then (re)configure the MAC
chip (separate or built into the CPU) to match. If the poll isn't happening or has a bug, you have problems like
described above.
Question 2:: When I use tftp, there are some problems. My terminal always displays "Loading: T T T T T T T
T T T T T T T T T T T T T". The whole information as follows:
U-Boot 1.1.4_XT (Jun 6 2006 - 17:36:18)
U-Boot code: 0C300000 -> 0C31AD70 BSS: -> 0C31EF98
RAM Configuration:
Bank #0: 0c000000 8 MB
Bank #1: 0c800000 8 MB
Flash: 2 MB
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
Hit any key to stop autoboot: 0
XT=> help tftp
tftpboot [loadAddress] [bootfilename]
XT=> tftpboot 0x0c700000 image.bin
TFTP from server 192.168.0.23; our IP address is 192.168.0.70
Filename 'image.bin'.
Load address: 0xc700000
Loading: T T T T T T T T T T T T T T T T T T T T
Retry count exceeded; starting again
TFTP from server 192.168.0.23; our IP address is 192.168.0.70
Would someone give me some suggestions?
Answer 2:: (1) Verify your TFTP server is working. On a machine (not the TFTP server nor your
development board) use tftp to read the target file.
$ tftp 192.168.0.23 get image.bin
14.2.15. Why do I get TFTP timeouts? 167