MPC5777M BAF

[christopheple]

Hi,

I would like to boot the e200z4 core of MPC5777M from internal Flash.

I have understand that i shall write in flash a boot_header with the start address of my code for the e200z4.

I would like to know where i can find the info about the job done by the BAF about core initialization : MMU, cache, register value ..

How can i know the core state when the BAF will branch to my entry point of my e200z4 code ?

Does the 2 32bits fields "configuration bits" of the boot header allow some customization of the BAF core initialization ?

I do not find the answers of my question in the MPC5777M reference manual.

Thx

[petervlna]

Hi,

A1: The BAF functionality is described in reference manual chapter 61.1 Introduction.

A2: your core state is defined by boot header (reference manual chapter 7.11.2.3 Search boot header and boot options)

      The cores defined by boot header will start on addresses provided in boot header:

The activation of cores is done by BAF. All cores will start in DRUN mode if they are defined in boot header.

A3: Yes, they will define the active cores. However you have to provide reset vectors for active cores also.

Peter

[christopheple]

Thx, but the (reference manual chapter 7.11.2.3 Search boot header and boot options) explain how to request to the BAF to branch in our code but it does not indicated any core status like MMU.

I would like to know for exemple: what is the "msr register value" at my code entry point ? and what are the TLB enabled inside the core ? It is a major point if you want to set up a specific MMU configuration for an embedded software.

The only solution, i have is to use a JTAG probe and break at my code entry point and read registers and TLB.

As, i have order JTAG probe and board and did not yet received, i expected find these informations in the reference manual, do you think that the reference manual contains this information ? or may be a application_notes ?

Moreover, i wonder if the BAF given in MPC chip is a usefull one with more fonctionnality that a specific embedded system needs. Is it a normal process to change to BAF by a custom one with only the needed functionality for our embedded system ?

Christophe.

[petervlna · Accepted solution]

Hi,

The BAF in not intended to be changed. On some PPC devices it is also locked as OTP.

BAF flash block is defined in RM:

Your MSR reset is defined in Table 7-2. Reset settings for e200z resources. BAF leaves MSR with reset value.

There is no TLB:

BAF is defined by NXP. Customer can erase BAF on MPC5777M, but I strongly recommend you to leave BAF flash block untouched as this block is not intended to be modified by user.

Peter