TMS320F28388D: CSM Password

Hello Chao,

The addresses 0x5f01x corresponds with the addresses of the CSMKEY registers. The On-Chip flash tool writes to these registers to unlock the zone.

I'll explain the 4 buttons:

• "Program": Programs the passwords entered in the 4 fields to the CSMPSWD fields in user OTP. The zone select block where these passwords will be programmed depends on the value in the LINKPOINTER field
• "Lock": Locks the zone if the passwords entered in the 4 fields matches the passwords in the active zone select block
• "Unlock": Unlocks the zone if the passwords entered in the 4 fields matches the passwords in the active zone select block
• "ECSL Unlock": Disables ECSL Tripping. When ECSL is locked, any breakpoint in secure code will disconnect the JTAG from the device. If CSMPSWD0 and CSMPSWD1 in the On-Chip flash tool match the passwords programmed in user OTP, ECSL tripping will be disabled and the user will be able to set breakpoints in secure code, however the zone will still be secure and data reads to secure resources via JTAG/memory browser will still return 0

When a DCSM zone is locked, all User OTP locations become secure, so if you've programmed CSM passwords, you must unlock the zone first before reading Z1OTP_JLM_ENABLE

Hello Jones,

so it means:

1. "Program" can be used to write the password into OTP.

2. in the software i have to write the code to do the Password matching flow with CSM password to unlock the Zone, so i will be able to read the OTP registers.

Q: is it correct?

Q: if i have both JTAG password programmed and CSM password programmed, when unlocking the JTAG port, what should be the unlocking sequence?

do i have to unlock the Zone with CSM password first, then do JTAG  unlock? or i dont need to unlock the Zone with CSM password?

The exact case what i have is i have the JTAG lock feature implemented(JTAG lock is enabled and JTAG password is programmed into the OTP), but i find out the OTP register however is still readable, regardless if the JTAG is locked or unlocked. I can use a piece of code in the software to read the JTAG password register and then i have the password, it is not secure.

After reading some parts in the reference manual, i think CSM password is used to make the OTP registers no more readable, thats why i am asking.

Q: what i have also read is there is Password Lock, will it protect the OTP JTAG password register from being read? Or it protects only CSM password in OTP from being read? Finally, what do i have to do if i would like to protect the JTAG password OTP registers from being read?

Thanks.

1. Yes this is correct

2. You don't need to unlock the zone in your software, this can be accomplished through the CCS On-Chip Flash tool via JTAG

Q: To unlock the JTAG, open your target configuration/ccxml file, click Advanced -> JLM, and enter your JTAG passwords. Then you should be able to connect to the target as you would normally.

Unlocking the CSM passwords is not necessary to unlock JTAG, however you must lock the zone using the CSM password to prevent the JTAG password from being viewable by your software.

Password lock makes it so that the CSM passwords are secure when the zone is locked. Without password lock enabled, the CSM passwords can be read in the OTP. You MUST enable password lock in your end application to protect your passwords. All other DCSM settings such as the JTAG password are secure whenever the zone is locked.

I did the following:

1. I programmed the CSM password, the target can be connected, but when i try to flash the target, it reports error, unfortunately i dont have any more the error message. in order to perform the flashIng, i have to type in the CSM password and click the "Unlock" button, then i am able to do the flash. But every time click the unlock is not what we want.

2. then i was checking the Z1_GRABSECT1R (Zone 1 Grab Flash Status Register 1), as i see from the register content view every byte is 11, i tried to programm it to 10. i only use CPU 1. So the content in Z1_GRABSECT1R is now 0AAAAAAA(i dont know what is the default value, i tried to programm FAAAAAAA, it does not work). 

after step 2, i can connect to target and then perform the flashing without CSM passowrd unlock. But the programm does not run, so i am trying to programm the Z1_GRABRAM1 and Z1_GRABRAM2(Zone 1 Grab RAM Status Register 1/2). then error occurs as below.

What should be the correct value?

Hello Chao,

This error usually means the location in flash you are programming has bits that were already programmed to a 0, however you are trying to program these bits to a 1, which is not allowed in USER OTP. Can you unlock the zone using your CSM passwords and view the values currently programmed between 0x78000 and 0x78040? This will confirm whether you are attempting to program any bits from a 0 to a 1.

Thank you,

Luke

Hello,

as shown in the picture, i think i have put the correct value in.