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iMX35 eSDHC boot example

Question asked by Michael Moran on Jun 18, 2014
Latest reply on Jun 18, 2014 by igorpadykov

I am embarking on the journey of booting an iMX35 board from an SD card (eSDHC-1) using the internal boot mode.

 

After much investigation of the u-boot source code, it appears that I will have the dubious distinction of being the first to try this. Given the age of the iMX35, I find this surprising. However, a quick check of the latest errata turned up nothing that indicates this can't be done.

 

In my mind, it seems that "all that needs to be done" within the first 2KB (besides filling in the HAB flash header etc) is to use eSDHC-1 to read in the remaining portion of the first stage boot loader from the SD card into internal RAM.

 

And... given that the internal boot ROM has already initialized eSDHC-1, this should be "easy"... right?

 

I have no experience with the SD command language, and finding/reading the appropriate parts of that spec is on the agenda.

 

But a good short-cut "alternative" is to ask this community if they already have an example for this operation... so here it is

 

Does anyone have any example source code for reading the next "n" blocks from the SD card (in assembler)?

 

thank you,

mike

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