Uncertainity in PSRAM,NOR FLASH,USB

[El_Chez]

Hello Team,

 

I am using STM32N657X0H3Q,

 

1. I am planning to integrate external RAM; however, the mentioned standard PSRAM, APS256XXN-OBR-BG, is not readily available on the market, so I chose to upgrade to DRAM, APS512XXN-OB9-BG. Is this upgrade safe?

 

2. Also, are there any alternatives to MX66UW1G45GXDI00 that can serve as a good NOR flash?

 

3. Regarding the USB-C connection, I am using a much simpler structure here, where I have left the VBUS Floating(I do not intend to use this USB to drive anything or for power delivery, just using it to communicate with pc and STM32CubeIDE) as shown in the picture below. Can you please let me know if this is a viable USB connection and if it's good enough for communication with STM32CUBEIDE ?

4. 

   Thanking You

[FBL]

Hi @El_Chez,

3. VBUS sensing is required for a self powered USB device so it can correctly detect host connection and disconnection, and disable the USB pull-up when VBUS is absent. If the device is bus powered, then VBUS must also be monitored to ensure the host is supplying power.

[El_Chez]

Thanks for the guidance, can you share me any reference schematic if you have one,

Thank you.