Using fuses other than OCOTP_GP1/2 for general purpose

[rowangifford]

Hi,

We would like to store some data in the OTP and I'm trying to see which registers are safe to use. I've been looking at From  IMX6Q Reference Manul Page 3995. Also the table detailing all used registers in the reference manual section 5.2 Fusemap, page 345.

OCOTP_GP1 and OCOTP_GP2 are clearly for general purpose.

We don't use secure JTAG, can we use the OCOTP_RESP0 and OCOTP_HSJC_RESP1 registers?

The reference manual seems to suggest that Memory Related Info registers OCOTP_MEM1-4 are not used, are these available?

I'm cautious of writing to registers other than GP in case there is some undocumented configuration there.

Many Thanks,

Rowan

[igorpadykov · Accepted solution]

Hi Rowan

OCOTP_MEM1-4 may be used during factory testing, so not recommended

to use it. JTAG OCOTP_RESP* can be used for customer data.

Best regards
igor
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[rowangifford]

Hi Igor,

Thanks for the quick reply, understood we'll avoid OCOTP_MEM1-4.

JTAG OCOTP_RESP* can't be read once they are locked (page 4022 of reference manual), which means if we want to use these we can't lock them after programming.

Also could I just confirm that the general purpose registers OCOTP_GP1* are ok to use? My understanding is they are general purpose for customer data but a reply from NXP Lydia in this forum post suggests they are used internally? i.MX6 OTP fuses customization 

I would not recommend using GPR1 or 2 for general data storage.  These locations are used by the i.MX6 ROM code.

Are there any other fuses safe to use?

Thanks,

Rowan

[igorpadykov]

Hi Rowan

yes general purpose registers OCOTP_GP1* are ok to use

Best regards
igor