Ho to program MPC5744P with MC33907

[xiaoguangchang]

I use MC33097 and MPC5744P for one project. However, I fail to program MCU due to frequent resets after MC33097 is configured to normal mode. The MCU I programmed is not empty and is has bootloader and application SW.  I do can program when MC33097 is configured to debug mode.

My questions are  

1. How can I program the MPC5744P when MC33097 is configured at normal mode? According to AN4766, it seems that my bootloader need to disable the watchdog refresh during INIT_FS or Normal_WD state of the fail-safe logic. But is there somebody advise me how to do so?
2. To support ISO26262, MC33097 has to be configured in normal mode.  After PCB assembly, the first time the MCU is powered, the flash memory of the MCU is empty and need to be programmed. How can I program an empty MCU if MC33097 operates at normal mode?  Do I need to jump MC33097 to debug mode for the first programming?

[lukaszadrapa]

Hi,

- empty flash: if your flash programmer allows you to execute scripts before programming, you can write short script which will disable the watchdog. If you can't do that, the only way is to put the SBC chip to debug mode.

- bootloader: there are two options - either disable the watchdog before firmware update or refresh the watchdog periodically. If you use SSD flash drivers, you can use callback function to refresh the watchdog.

Regards,

Lukas

[claudio_b]

Hi Lukas,

when you say "- empty flash: if your flash programmer allows you to execute scripts before programming, you can write short script which will disable the watchdog. If you can't do that, the only way is to put the SBC chip to debug mode."

What do you mean? How can I do that?

Thank you

[xiaoguangchang]

Hi Lukas,

Thank you for the response. Your answer is pretty instructive. I am wondering in bootloader how to either disable the watchdog before firmware update or how to refresh the watchdog periodically. Can you give me some suggestion?

Thanks 

Xiaoguang

[金翅大鹏鸟]

Hi Xiaoguang Chang,

   It seems that I met the same phenomenon as you described. I used MC33908NAE to power the MC5744P,When I power up the board with 24VDC,MC33908NAE outputs 3.3VDC,but after 1-2 second ,MC33908NAE is shut down .Is the phenomenon the sam with yours? And can you tell me how di you solved the problem?