STM32F072 USB_NOE pin

fggnrc2 · ‎2014-05-30

Posted on May 30, 2014 at 11:24

Hello,

I'm planning to use a STM32F072 for a USB device.

When I browsed its datasheet, I found that PA13 can output USB_NOE as alternate funtion.

There is no functional explanation of this pin in the reference manual, so I wonder what this pin does when the USB peripheral is enabled.

Perhaps, it is an input that enables the D+ pull-up when the USB bus is powered, but I may be wrong.

Do you have any ideas?

EtaPhi

#usb #stm32 #stm32f072

fggnrc2 · ‎2014-05-30

Posted on May 30, 2014 at 14:24

The RM0091 that was issued this month gives some piece of information about USB_NOE:

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.

This means that my suggestion was wrong.

BTW, how is it possible to output USB_NOE on PA13?

The RM0091 says nothing about it...

EtaPhi

tsuneo · ‎2014-05-31

Posted on May 31, 2014 at 16:52

> how is it possible to output USB_NOE on PA13?

On the ''Table 14. Alternate functions selected through GPIOA_AFR registers for port A'' of

, you'll find that USB_NOE is assigned to AF2 at PA13

Now that you may code it on your firmware,

a) following to ''A.4.2 Alternate function selection sequence code example'' on the reference manual RM0091

OR

b) apply STM32F0xx_StdPeriph_Driver, referring to STM_EVAL_COMInit() in

STM32F0x2_USB-FS-Device_Lib V1.0.0\Utilities\STM32_EVAL\STM32072B_EVAL\stm32072b_eval.c

Tsuneo

fggnrc2 · ‎2014-06-02

Posted on June 02, 2014 at 09:50

Tsuneo,

thnx for replying to my silly question.

The reply was under my very nose, but I couldn't see it!

EtaPhi