STM32F405/7 DFU USB. Strange behavior at the start of the bootloader

[rm2399]

Posted on January 25, 2016 at 18:35

Hello

I observe

here

a strange phenomenon

,

maybe

someone can help me

.

After a reset with boot 0 signal = high, the DFU mode does not start always. After the reset, it takes sometimes several 10 seconds until the DFU Mode starts. Sometimes I have to send a second reset. Was tested with a STM32F4 discovery and with our own board. On our board a STM32F405VGT6 1 is installed. On the Discovery a STM32F407VGT6 1. Both have the bootloader version 0x31. The Pins PA10, PB5, PB11 and PC11 are at a fixed level (GND or VDD) There seems to be a Race Condition to be, because it sometimes works 20 times in succession and then every other time not.

It happens

regardless of whether

the

reset

is generated

by hardware

or

bootloader

via

NVIC_SystemReset()

is called.

Has anyone ever seen this effect? And someone knows a solution for this? #stm32f4-dfu-usb-bootloader

[Tesla DeLorean]

Posted on January 25, 2016 at 19:15

Perhaps there is a clock start issue, the System Loader benchmarks the HSE against a list of expected/supported frequencies using HSI.

[rm2399]

Posted on January 25, 2016 at 20:05

That's what I

had thought too

.

But

on the

Discovery

is an

8

MHz

clock

,

which continues

even

after a reset

.

On our

board

, it is

a

16

MHz

clock

. But even there, it works sometimes.

On our

board

the

clock

, however,

is switched off

at reset

.

The clock generator

starts

in

about 600

us t

o

a valid signal

.

I have

further tested

with the

F4

Discovery

.

When

R68

removed

and works with the

built-in

quartz

,

then

again, the

clock

is stopped

after a reset

.

Appears

the problem

(no

DFU

USB

Device

detected

),

then

the

clock

remains stopped

until

the

DFU

mode is

recognized by the PC

.

You can

reproduce

the effect by

GND

on

one puts

the

F4

Discovery

pins

PA10

,

PB5

,

PB11

and

PC11

(

I use

here

jumper

cable

)

and

a

jumper

in

boot0

to VDD

sets

.

If you press

the reset button

a few times

now

,

then

the

DFU

USB

device

is not detected

on your PC

.

[richard239955_stm1_st]

Posted on May 19, 2017 at 10:00

Hi Rolf,

Did you manage to find a solution for your problem? I think I'm having the same issue (see thread

https://community.st.com/0D50X00009XkY83SAF

), and still trying to find a workaround. Or, did you have to make a change to the board?