Hello,
Hopefully my subject is not too general. I am brand new to the i.MX8 and am a bit out of my depth. My company is designing a board that incorporates the MIMX8ML8DVNLZAB, SDINBDG4-32G-I1 (eMMC), MT53E512M32D1NP046WT:B (DRAM), and PCA9450CHN (PMIC). Our design is based off of the 8MPLUSLPD4-EVK. We have the schematics and layout files for that EVK and we followed it very closely. Our customer needs to use USB Serial Download boot mode and provided us the documentation for how they use it. Their procedure works fine when I follow it on the 8MPLUSLPD4-EVK, however, when we received our prototype boards, I was not able to reach the end of the procedure. The procedure goes like this. Select the desired boot mode via SW4, which in this case is "0001". Connect PC to the "DEBUG" port. This causes 4 new ports to show up on the PC. Then, connect PC to "J6", or "PORT1". This all works fine on both (EVK/our design) boards. The next step is to power on the board. When I power on the EVK, PORT1 enumerates on the PC and shows up as a blank processor, which is what is shown in the procedure as the desired outcome. However, on our design, when I power up the board that port does not enumerate and nothing shows up on the PC. Our debug attempts here were very numerous. I will not explain all we've done here (if asked I will). An extremely short version is, we check all the rails from the PMIC to the i.MX8 and they're all good except the 0.9V output of LDO4 of the PMIC, that is 0V. Not sure if that's relevant. I have no access to any connections between the i.MX8, DRAM, and eMMC so I'm not sure how to check any of that (suggestions?). We have done tests to try and confirm the i.MX8 is active and they suggest it is, but I don't feel like that is confirmed (suggestions to confirm this?). We have done many tests to prove the port is working properly, and when I compare our board to the EVK everything I've measured is the same. I have some PPTs that cover what was done I can include if needed. I have been approved to share schematics also if needed. Assume that will be the first thing anyone needs.
I have never interacted on this platform before, so I'm not sure what is customary. If someone could respond and fill me in on what is needed. Again, I have not included a ton of information on our debug efforts because it's extensive, but whatever anyone requests I can provide.
