If an OMAP-L138 is strapped to boot from NAND (BOOT[7:0] 0xx0 1110), is it possible to modify the BOOTCFG register via JTAG to switch to UART(BOOT[7:0] xxx1 0110) and soft boot the CPU?
Is there any example code to perform that sequence?
Thanks,
Brian
Unfortunately no, the bootcfg register values are latched on power on reset only, where in the boot pins are sampled. You cannot manipulate the bootcfg pins post boot/power power up and then trick the on chip rom code to boot from UART.
Why do you need this feature?
Regards
Mukul
Don't forget to verify answers to your forum questions by using the green "Verify Answer" button.
For production programming we need control as the flash is not pre-programmed.
The board has them strapped for functional use.
Brian,
As Mukul described it is not possible to change the BOOTCFG after power-on but you do not require to change the BOOTCFG register to achieve secondary soft boot over a different medium. Basically what you are trying to do is exactly how the xloader and uboot are designed to work on OMAPL138. Please look at the description of the second Stage bootloader
http://omappedia.org/wiki/Bootloader_Project#OMAP_Boot_Sequence
You can look inside the linux PSP source to see how this is implemented.
Regards,
Rahul
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Based on the internal discussion, I understand your hardware and boot situation a little better. Most of the TI tools for programming the flash are UART based which would have helped you a lot considering you are looking for solutions to program your production boards but considering your boot pins are strapped for NAND boot and contents of the NAND are blank, the only way for you to program the NAND would be over JTAG.
If you download the Serial Flash and boot utilities that are provided here,
http://processors.wiki.ti.com/index.php/Serial_Boot_and_Flash_Loading_Utility
we provide a CCS based NAND writer in the package that you can use to program your boot image to NAND. This would require you to connect to device over JTAG using CCS and run the NANDWriter to write the boot image to NAND. There are ways to automate this process without using the CCS GUI which I can suggest after you let us know if this works for you.
Let us know if you have any follow up questions. For us to be able to help you, the more we know about the system the better guidance we can provide.
PS: Based on the other questions forwarded to us in the internal email, we thought that the following wiki articles will allow you to make informaed decision regarding boot. Most of the information regarding the OMAPL138 boot is provided in form of an application Notes and supporting wikis. Here are the links that you can provide to the customer: