Nethra wrote:

hi, i am using 8248 custom board. Now i want check the board by toggling the led without using u-boot.

Which means your question is probably of topic for u-boot list. Check a general embedded programming list.

To get you started, you will have to do some of the cpu/board initialization done u-boot in your code before you can flip that LED which could be as short as a few instructions that modify a specific memory location or significantly more complex routines depending on how the LED is interfaced.

Your CPU manual and board schematics and datasheet/user guide of the parts on the board and crafty use of google are your friend. You need to know some assembly programming for your CPU and be comfortable debugging via BDI debugger.

Tolunay