MPC5775B – Application to RAppID Bootloader transition

[NXP_007]

Hello NXP Team, I am using MPC5775B with RAppID Bootloader for CAN flashing.
I do not have the RAppID FBL source code, so I cannot modify the existing FBL.
Is there a supported mechanism for the running application to request the existing RAppID FBL to enter programming mode?
If yes, what is the required Application → FBL entry sequence for MPC5775B?
Does this require a specific reset/boot mechanism, or does RAppID provide another way to request FBL from the application?

[NXP_007]

@lukaszadrapa Can you help me out on this topic?

[lukaszadrapa]

Hi @NXP_007 

As Peter said, you can't request  to run the bootloader from your application. The bootloader starts after each reset and it waits pre-defined time if it gets a response from RAppidBL application running on PC. If not, it starts the application. 

The delay can be changed by user. See "2.7 RAppID Boot Loader Flash Algorithm (RBF)" in the user manual for details. 

Regards,

Lukas

[NXP_007]

Please do let me know if you have any solution to the problem.

Thank you,

[petervlna · Accepted solution]

Hello,

There is no built-in, documented API in the RAppID FBL for the running application to programmatically request FBL entry. The RAppID bootloader for MPC57xx is a closed-binary, flash-resident bootloader (distributed as a pre-compiled .rbf file) with no source code provided and no modification possible.
The standard mechanism to trigger it is a reset + boot-time flag check, not a runtime call from the application.

Best regards,

Peter

[NXP_007]

Thanks Peter. Understood that the mechanism is a reset followed by a boot-time flag check. Since we do not have the RAppID FBL source code, could you please clarify what boot-time flag/condition the RAppID FBL for MPC5775B checks, and how the application can set/request it before reset?

Is this a specific RAM address/magic value, reset-cause condition, configuration field, or another mechanism? If there is an application-side procedure or documentation for setting this flag, could you please share it?