I have a custom board using MCIMX6G3CVM05AA and would like to use the TAMPER pins as GPIOs.
According to IMX6ULRM the TAMPER_PIN_DISABLE[1:0] fuse has to be set to 0x3.
Trying to do this using uboot fails as following:
=>fuse read 0 3
Reading bank 0:
Word 0x00000003: 0001006b
=> fuse prog 0 3 0x0031006b
Programming bank 0 word 0x00000003 to 0x0031006b...
Warning: Programming fuses is an irreversible operation!
This may brick your system.
Use this command only if you are sure of what you are doing!
Really perform this fuse programming? <y/N>
mxc_ocotp fuse_prog(): Access protect error
According to similar threads on this forum this is not possible in the G3 version as the TAMPER_PIN_DISABLE[1:0] fuses are factory programmed.
Please help me clarify the following questions:
1. Are the G3 fuses pre-programmed? If yes, where do i find this information?
2. How exactly does "fuse prog" in uboot work, does it program fuses from '1' to '0' or from '0' to '1'?
BTW: According to the provided schematics the IMX6ULEVK has a MCIMX6G3CVM05AA using TAMPER pins as GPIOs while it is actually populated with an MCIMX6G2CVM05AA.