cancel
Showing results for 
Search instead for 
Did you mean: 

MCU is not recognized as USB storage device

Sophi
Associate II

Hi all - I'm new to the STM ecosystem and I've been stuck on an STM32H743/ Micropython issue.

My (custom) board can upload Micropython firmware via both SWD and DFU. So DM/ DP work.

VCC measures 3.21V, maybe a little low, maybe just my DMM.

I'm not able to get this board to communicate over TX/ RX or see the board as a USB device. 

The STM32H743 does not need series resistors on DP/DM and it has an internal pullup on DP. 

I built a new Micropython firmware with (AFAIK) the correct settings/ pins for USB in mpconfigboard.h

-Do I need to configure the internal pullup? And how? 

-What am I missing?

TL;Dr custom board w STM32, what does it need to run microPython?

5 REPLIES 5
Pavel A.
Evangelist III

 

I'm not able to get this board to communicate over TX/ RX 

Over which TX/RX? Is there a UART besides USB?

Thanks Pavel. The STM32H743 has an internal UART at PD5 and PD6.

Using a USB to UART cable I am not able to reach the chip. My computer sees the cable, but not the chip.

Separately, I believe the USB pins are working since I can reach the board over DFU.

Pavel A.
Evangelist III

PD5 and PD6 correspond to USART2. Cannot tell whether these pins are free to use for USART2, because the board is custom.

FBL
ST Employee

Hi @Sophi 

You don't need to configure the internal pullup since it is already integrated in the chip. Also, you mentioned your settings/ pins for USB are detailed in mpconfigboard.h and you did not attach the file to the thread. So far, you should provide more details so that we can help you!

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Sophi
Associate II

Hello,

I am still not able to get this board to show up as a MSC or communicate over UART.

Micropython is loaded into 0x08000000 and this address is verified with STM32CubeProgrammer.

I can use STM32CubeProgrammer only over ST-Link (SWD) or DFU. I'm not able to reach the chip's UART2 by TTL cable or Putty. 

I've attached mpconfigboard.h configuration file with what I hoped was correct USB and UART settings.

The external crystal is 12 MHz. Power to the STM32H743 is 3.21V

Thanks in advance!