How do I select parts that support VDD USB using CubeMX?

[Andrew Lohmann]

The most suitable parts are STM32L052 or STM32L072 48 pin or 64 pins parts or any other support VDD USB and how do I select that option using CubeMX?

Secondly what is the USB_NOE pin for I can not find any reference to it. If I use it presumably I can't reprogram or debug once this pin has been selected where there is a conflict?

Explanation - the application uses two NiMH batteries which do not always have 3V minimum supply for the USB port. So I either need to use 3 cells, a power switch over or some other means if I can not select a micro-controller that provides VDD USB.

[TDK]

VDDUSB is an input. It's something you'll need to supply (with 3.0-3.6V). It's not an output that the chip generates. It sounds like you're trying to use it as an output. Apologies if I've misunderstood.

> Secondly what is the USB_NOE pin

The reference manual has one sentence on it. Sounds like it can be used to indicate activity but isn't really specified in detail.

The output enable control signal of the analog transceiver (active low) is provided externally on USB_NOE. It can be used to drive some activity LED or to provide information about the actual communication direction to some other circuitry.

> If I use it presumably I can't reprogram or debug once this pin has been selected where there is a conflict?

Since it shares a pin with SWDIO, you can't connect over SWD if you remap the pin. You can still hold the chip in reset to connect with SWD, though.

[Andrew Lohmann]

Thanks TDK

Therefore I don't need USB_NOE pin an LED can be driven from another port pin in software if I decided to add such an LED.

I understand that VDDUSB is a power input and needs to be 3.0 - 3.6V but the microcontrollers I have selected using CubeMX don't have that pin. My question is therefore how do I search for a microcontroller that does have that pin?

[Andrew Lohmann · Accepted solution]

I have found which variants support "VDD_USB" in the datasheet I had been searching the datasheet using the wrong string "VDDUSB". Also CubeMX does not have that selection parameter.

It turns out that the 48 pin or higher microcontrollers I had selected do have that pin but the 32 pin microcontrollers I had selected do not have that pin. CubeMX suggests that none of those microcontrollers have that pin unfortunately.

Thanks