Overriding Default boot Sequence in AM335x

sram

Hi,

We are designing AM335x based reference board. Currently we have selected the boot sequence as 10011 NAND NANDI2C MMC0 UART0. Now we want to give a jumper option to override this boot sequence and boot from MMC SD card. Please suggest how to do this in hardware? (Some of the Reference boards already implement this option).

Regards

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

Boot sequence 11001b has MMC0 as first boot device. You have to disconnect the pulldown on SYSBOOT2 and pull the line up, that's all.

0 sram over 9 years ago in reply to Biser Gatchev-XID

Intellectual 680 points

Hi Biser,

Thanks for the response.

We want the First boot device to be NAND flash always and alternate boot device as MMC0. So these 2 boot options are available in SYSBOOT 10011b. So with this configuration, the system boots from NAND flash by default. But we want to override this to boot from MMC0 in some instances. So with a jumper option it is possible to do this. I was wondering how to do this. The SYSBOOT option 11001b doesn't have NAND option?

Regards.

0 Biser Gatchev-XID over 9 years ago in reply to sram

TI__Guru**** 393215 points

If the NAND is fixed as your first boot device and it has a valid image at the correct location the processor will always boot from it. You can only override this if you switch to a sysboot setting that has MMC0 as first boot device.

0 sram over 9 years ago in reply to Biser Gatchev-XID

Intellectual 680 points

Sure Got it.
Thanks.

0 Jonathan Cormier over 9 years ago in reply to sram

Genius 3871 points

It is common in the 335x u-boot environment to check for a MMC and then attempt to boot from it. Note this still technically loads u-boot from the NAND but the MMC kernel and filesystem can be booted instead of the nand one. Not sure if this fits what you were looking for.

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Overriding Default boot Sequence in AM335x