Uniq ID and lock opeartion for OCOTP

[emdev]

Dear experts,

I have two questions.

1. Someone recommended to use CFG0(0x01), CFG1(0x02) as uniq ID.

    (https://community.nxp.com/t5/i-MX-RT/Read-UID-Unique-ID-on-i-MXRT-RT1050/m-p/1202637)

    There are 4 x 32 bits in TESTERs.

    So I wonder that only 2 x 32 bits can guarantee uniq ID or not.

2.I want to lock some fields(MAC0 and/or MAC1) in OCOTP with lock register, but it can't be done.

  After write MAC0 and/or MAC1, it must be protected from overwriting.

  For this, MAC_ADDR field in HW_OCOTP_LOCK(0x400) must be set.

  2.1 When I write MAC_ADDR field, it can't be written with below code,

  OCOTP->LOCK = OCOTP->LOCK | 0x00000100;

  2.2 There is error and can't be written with below code.

  OCOTP_WriteFuseShadowRegister(OCOTP, 0x00, OCOTP->LOCK | 0x00000100);

  I want to know how I can change Lock register in OCOTP.

  Can Lock register in OCOTP only be changed with "NXP MCU Boot Utility"?

[jingpan]

Hi emdev,

1. I'm afraid you can't only use one 32bit register. The unique ID is not meaningless random number. Please see table 22-4 in page 776.

2. You can't write OCOTP->LOCK. It is read only register. The lock bit should be write same as other bit in ocotp. 

Regards,

Jing

[emdev]

Dear Jingpan,

Thanks for your reply.

About answer #1, I can understand what you mean with table 22-4 in page 776.

But I can not understand answer about #2.

I can see below table in page 796.

You said OCOTP->LOCK is read only register, but above table tell me that this register is RW.

Anyway, would you let me know how I can lock OCOTP->MAC0, OCOTP->MAC1, OCOTP->GP3?

Thanks.

[jingpan]

Hi,

But if you look into this register, you'll find almost none of its bit can be written.

You can use OCOTP_WriteFuseShadowRegister(...) to program these bits. Please note there is a mapping relationship between shadow register address and efuse address.

Regards,

Jing

[emdev]

Dear Jing,

I used below codes.

regAddr = 0x0;

Lock_value = OCOTP_ReadFuseShadowRegister(OCOTP, regAddr);
PRINTF("Lock value : 0x%2X : 0x%08X\n", regAddr, Lock_value);

Lock_value = Lock_value | 0x00000100;

if (kStatus_Success == OCOTP_WriteFuseShadowRegister(OCOTP, regAddr, Lock_value))
{
PRINTF("OCOTP Write operation success!\r\n");
PRINTF("The new value is 0x%08X\r\n", OCOTP_ReadFuseShadowRegister(OCOTP, regAddr));
}
else
{
PRINTF("OCOTP write operation failed. Access deny!\r\n");
}

I used register address 0x00 for LOCK and I used OCOTP_WriteFuseShadowRegister() to change register value.

But I can see "OCOTP write operation failed. Access deny!".

I checked that OCTP->CTRL value is 0x3E770200.

Would you tell me full example codes to change OCTP->LOCK?

Thanks.

[jingpan]

Hi,

You code seems fine. What's the read back value of Lock register? The write function report fail is because CTRL[ERROR] bit is 1.  This is the condition of ERROR bit become 1

If you modify the OCOTP example from writing MAC to writing MAC_ADDR lock, can it work?

Can you use MCUBootUtility to read out all fuse map?

Regards,

Jing

[emdev]

Dear Jing,

Below message is output from above test codes.

OCOTP controller version: 0x06000000

Lock value : 0x22 : 0x87654321
Lock value : 0x23 : 0x12345678
Lock value : 0x 0 : 0x40128003
OCOTP write operation failed. Access deny!
Lock value : 0x 0 : 0x40128003

About MCUBootUtility, I can use it.

Would you tell me what I should check with MCUBootUtility?

I'll check it.

Thanks.

[jingpan · Accepted solution]

Hi,

When you write mac address lock value, you should only write the value itself, don't write other bit again. Here you should write 0x100, not 0x40128103. 

Regards,

Jing

[emdev]

Dear Jing,

With your guide, I can set Lock controls register.

Thanks.