Shadow Flash programming and NVUSRO

[fscheidl]

I want to use an MPC5602D with a supply voltage of 5V. I read that I should program this in the NVUSRO[PAD3V5V] register in the shadow flash of the device in order for it to comply with the specified electrical characteristics - but it should work either way, right?

Now I am relatively new to Freescale products. Can I program the shadow flash via the Boot Assist Module only? (I am using this to program the MCU) If yes, is there any tutorial/example code for that? If no, what else do I need?

Thank you in advance!

[davidtosenovjan · Accepted solution]

The PAD3V5V pin determines the slew rate for output drive pads to keep the rise time the same for a 3V configuration and 5V configuration. Yes, it is work in both cases, it is not dangerous anyhow to have it set in opposite configuration.

Shadow flash programming may be potentially dangerous because there is also censorship information there. Censorship feature is a way to prevent unauthorized access to the device. However it is very sensitive thing. It is needed to use it very carefully, because an inappropriate usage can lead in making the device useless. If user accidentally erases shadow flash/row there is no chance to recover it (unless it had been though about before).

In other aspects shadow flash is normal flash memory and may be programmed common ways. Example you may find here:

https://community.freescale.com/docs/DOC-102582

I would strongly recommend to read mentioned appnote.