Other Parts Discussed in Thread: AM4372,
We have our custom board for AM4372 CPU and it works fine (made a lot of tests), we would like to make tests with AM4376 (version with secure boot). So on the same base of hardware we install AM4376 (secure boot rev), before we burn secure keys we had "CCC..." on UART0 but after we load new image with secure keys we don't have any data on UART0. Of course we have and use the VPP (pin21) for 1.7V when we burn secure keys for AM4376 (secure boot rev.).
There is any difference on pins between AM4372 and AM4376 (secure boot version) ?, we have NDA with TI but I need answer only YES/NO now. For family cpus AM437x is one technical documentation, as PMIC we use TPS65218b1rslr.