TMS320F280049C: Make a secured device unsecure

Wayne Huang said:

1) If the user already uses passwords but later on, the user decides not to use DCSM, is it possible to unlock the device with the correct passwords and then make it unsecure hereafter so that the user does not need to unlock it every time?

Since the first zone select block (ZSB) has the passwords, the link pointer needs to be moved to the next ZSB. And let the default passwords remain in the next ZSB. Since the PSWDLOCK bits are not 1111, the password locations cannot be read in the new ZSB. However, a dummy read of the password locations will enable the passwords to be read. The boot-ROM does this dummy read.

Wayne Huang said:

2) Does it make sense to set linkpointer to Zone_Select_Block19 (if any) with same default password ZxOTP_CSMPSWD1 0x47ffffff as the default password of Zone_Select_Block0?

In this way, every time F280049 powers on, it uses this same default password to unlock it by default.

Yes, this is possible.