LPC55S69 : used SRAM by BootROM

[EugeneHiihtaja]

Hello !

MCU has boot rom and secure boot rom what used for ISP, secure boot and etc.

Does it possible to know what exact SRAM area they use in worst case for all of those operations ?

At list it would be nice to know what exact ares  are not used in any booting flashing case.

I need to pass over reboot few KB of data and need to know what SRAM can be corrupted due usage if it by bootrom operations.

Regards,

Eugene

[Sabina_Bruce]

Hello Eugene,

The area used for the operations mentioned is the following area described in the table:

Best Regards,

Sabina

[EugeneHiihtaja]

Hi Sabina !

This is ROM and flash memory only. When bootrom is executed , it use some SRAM areas for variables and for peripherals.

are the specified somewhere ?

Regards,

Eugene

[Sabina_Bruce]

Hello Eugene,

The peripheral addresses and sram address are specified in same table as I listed above in the user manual. However it is not specfied( as in some Kinetis families), what is being used during the execution of the bootrom. In addition this area of sram should be freed once the the bootrom execution is finished and jumps to the application.

Best Regards,

Sabina

[EugeneHiihtaja]

Hi Sabina !

Can SRAM usage of bootrom clarified with developers some how ?

We need 2-4KB of space what should retain over  any type of reboot and any type of ISP flashing.

I can see a lot of nonused space in those small SRAM sections:

SRAM4, ( 0x20040000 -  0x20043FFF, size 16KB, used by PowerQuard if it enabled) 
SRAMX  ( 0x1400 0000 - 0x1400 7FFF, size 32KB )
             SRAMX_0 ( 0x1400 0000 -  0x1400 0FFF,   4KB used by Casper if it enabled )
             SRAMX_1 ( 0x1400 4000 -  0x1400 4FFFF, 4KB used by Casper if it enabled )
             SRAMX_2 ( 0x1400 6000 - 0x1400  65FF, 1.5KB is used by power API )
            SRAMX_3  ( 0x1400 8000 - 0x1400  85FF, 1.5KB can used by power API , if SRAMX_2 is not used)
SRAM USB ( 0x40100000 - 0x40103FFF, 16KB if USB interface in use ) 

And from other side if bootrom clean/wipe whole SRAM after ISP or over reboot, it would be nice to know about it.

Regards,

Eugene