STM32L496: Unable to go in DFU when use HAL_SPI_Transmit_DMA

[M4R10]

Hello guys,

I'm not new using DFU but I have this strange problem.

When I try to jump in DFU from my code, I get an "Unknown usb device" from my PC.

I have also 2 push button in my board. Reset and DFU pin (keep PH3 high ).

If I keep pressed DFU button and then pressing Reset it fall in the same state (Unknown device).

If I keep pressed DFU button and plug the usb (I get the power from usb) it works.

Investigating I discovered that commenting this line

HAL_SPI_Transmit_DMA(&hspi1,(uint8_t *)bProgADC,sizeof(bProgADC));

DFU works in every case.

What is very strange is that resetting MCU while keep pressed DFU button is not enough, I must cut the power and plug the usb cable while pressing DFU button to go in DFU.

While commenting that SPI line everything is fine

How HAL_SPI_Transmit_DMA can cause this?

How can I fix it?

Thanks in advance

--

Mario

[TDK]

Does your program use the USB at all? Are any other bootloader peripherals active during reset, possibly the SPI? What exactly does the DFU button do?

[M4R10]

My program use USB. It is configured as VCP

Bootloader peripheral are USB, USART1 and SPI1. When I jump to DFU from code I tried to stop/disable everything but still the same issue.

DFU button link PH3 to VCC. Pushbuttons are working, I checked with oscilloscope.