Arduino for STM32

the way it looks is in the bootloader20 a error.

The error on Bootloader 2.0 is that USB is not disconnected when leaving the Bootloader.
This means that there is no renewed enumeration of the CDC device.

one possibility is to patch the bootloader20
https://github.com/rogerclarkmelbourne ...

In your log, after the reset it switches to bootloader.

With the bootloader2.0 the testsketch is after the reset running (the LED is blinking), only the USB will not be initialised

I found out that I can with "dmesg -w -e" also test whether the SerialUSB works.

I use this test sketch
int8_t led = 0;
//#define USBD_ENUM_DELAY 500

void setup() {
pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
led = ~ led & 1;
digitalWrite(LED_BUILTIN, led);
delay(200);
}

I flash with ...

Try with ... in setup.

it doesn't work with that either

without a working serialUsb, I cannot use the bootloader20

With the orginal bootloader the serialUsb works also after a reset.

Right after the upload of the testsketch is the usb device available and the serialUsb works
# ls -l /dev/serial/by-id
insgesamt 0
lrwxrwxrwx 1 root root 13 16. Feb 19:53 usb-STMicroelectronics_MAPLEMINI_F103CB_CDC_in_FS_Mode_8D82067E4850-if00 -> ../../ttyACM0

after a reset or plug off, with ...

I loaded this test sketch after reflashing with each bootloader

int8_t led = 0;

void setup() {
Serial.begin(115200);
pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
if(Serial.available()) {
char c = Serial.read();
Serial.print("hello ");
Serial.print(c);
Serial.println();
}
led = ~ led ...

I have tested with another maple mini and other bootloader and find out:

With the orginal bootloader
http://docs.leaflabs.com/static.leaflabs.com/pub/leaflabs/maple-bootloader/maple_mini_boot.bin
the serialUSB works too after a reset or plug off

With the bootloader20
https://github.com ...

Which value of USBD_ENUM_DELAY should I test?
I have testet 100 and 500

with this /dev/serial/by-id the SerialUSB works also after a reset or power off:
usb-LeafLabs_Maple-if00
Setting Alternate Setting #2 ...
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 0110
Device returned transfer size 1024
Copying data from ...

I use this sketch:
int8_t led = 0;
#define csPin 7
#define csPin2 31

void setup() {
pinMode(csPin, OUTPUT);
pinMode(csPin2, OUTPUT);
digitalWrite(csPin, HIGH);
digitalWrite(csPin2, HIGH);
Serial.begin(115200);
pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
if(Serial.available()) {
char c ...