Legend:
Simple image header
(only size and destination address)
Initial software
1) Image for GP device
non-XIP memory booting
Mandatory
Configuration header
TOC and items
Optional
Initial software
Configuration header
TOC and items
2) Image for GP device
XIP memory booting
init-018
Initial software
3) Simple image for GP device
Peripheral Booting or XIP memory
booting
Public Version
Device Initialization by ROM Code
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The CH, which is optional, can contain several parameters set by users to speed up booting. It is further
described in the next section.
The mandatory part contains software that is loaded into the memory and executed.
An overview of the image formats is shown in
. There are two image types:
•
GP non-XIP memory booting: This image type is used for memories that require shadowing. The
image must begin with a simple header that contains information about the size to copy and the
destination. This format is described in
, Image Format for GP Devices.
•
GP XIP memory booting and peripheral booting: A GP image on XIP memory contains only code. The
first sector can contain CH. The GP peripheral booting image contains only code.
Figure 26-32. Image Format
26.4.8.2 Configuration Header
The CH is optional and is required only if the customer wants to use settings different from the ROM code
defaults (for example, clock frequencies, SDRAM/double-data rate [DDR] SDRAM settings, GPMC
settings). The CH can be present only when booting from a memory-type device (for example, CH is not
supported when booting from UART or USB). Therefore, the CH contains settings only for memory
booting.
The CH can contain up to four parts:
•
Settings: Clock settings (mandatory)
•
RAM: SDRAM/DDR SDRAM interface settings
•
FLASH: Flash interface (GPMC) settings
•
MMC/SD: MMC/SDIO interface settings
The beginning of the CH is a table of contents (TOC) pointing to each item (see
). Each TOC
item is a simple structure described in
. The complete CH (CH TOC and items) must fit in a
512-byte sector.
The ROM code identifies the presence of a CH by reading the first TOC item if it contains a known string
(CHSETTINGS, CHRAM, etc.). Then, the TOC is identified and searched until a 0xFFFFFFFF offset is
found. The CH is read and parameters are executed sequentially.
3570
Initialization
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated
