i.MX ProcessorsのトピックRe: IMX8M M4_DISABLE

IMX8M M4_DISABLE

wgentry3 — Thu, 21 Jul 2022 00:19:59 GMT

Hi,

My team is looking into disabling the M4 core using the fuses. According to the reference manual (IMX8MDQLQRM), the M4_DISABLE fuse is in the TESTER region. This TESTER region is locked by the TESTER_LOCK by NXP. This means we cannot disable the M4 core after purchasing the IMX8M chip. Is this reasoning correct?

Re: IMX8M M4_DISABLE

jimmychan — Fri, 05 Aug 2022 02:55:17 GMT

According to the reference manual, the related fuses in the tester field can be unlocked by setting the first two bits of TESTER_LOCK(0x400) register to 0. And then, you could disable the M4 core by setting M4_DISABLE(0x450) register to 1.

Re: IMX8M M4_DISABLE

wgentry3 — Wed, 10 Aug 2022 18:22:31 GMT

Thank you for your response,

My understanding is you can only transition fuse values from 0 -> 1 and 1 values are permanent and cannot be set back to 0. So there is no way to unlock a locked region. Is that correct?

Re: IMX8M M4_DISABLE

wgentry3 — Wed, 10 Aug 2022 18:26:47 GMT

Thank you for your response,

My understanding is that fuse values can only be transitioned from 0 -> 1, and the reverse is not possible. If we receive chips with the TESTER_LOCK = 0b11, then there is no way to set that to 0b00. Is this correct?

Re: IMX8M M4_DISABLE

jimmychan — Thu, 18 Aug 2022 02:39:07 GMT

Yes, if the TESTER_LOCK = 0b11, there is no way to set that to 0b00 and the related result is that the M4 core can't be disabled. Actually, if you don't need to use the M-core, there is no necessary to disable it. You could just leave it there unused.