STM32F0-Discovery: no tty - linux

Question

I am currently trying to send data to my STM32F0308 board via USART.
The data is supposed to be sent by a Python script using PySerial.
However, when I plug in the board, I cannot find the corresponding /dev/ttyXXXX.
The board is branched and I can flash code on it (STLink via USB), but there is no port visible.
dmesg shows that the computer is aware of the board:
[10364.101554] usb 1-3: USB disconnect, device number 10
[10368.044231] usb 1-3: new full-speed USB device number 12 using xhci_hcd
[10368.173948] usb 1-3: New USB device found, idVendor=0483, idProduct=3748
[10368.173956] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[10368.173959] usb 1-3: Product: STM32 STLink
[10368.173962] usb 1-3: Manufacturer: STMicroelectronics
[10368.173965] usb 1-3: SerialNumber: VÿnIxRT68\xffffffc2\xffffff87
Here is the output of lsusb:
Bus 001 Device 012: ID 0483:3748 STMicroelectronics ST-LINK/V2
Here's the output of ls /dev/tty*:
tty tty12 tty17 tty21 tty26 tty30 tty35 tty4 tty44 tty49 tty53 tty58 tty62 ttyprintk ttyS12 ttyS17 ttyS21 ttyS26 ttyS30 ttyS7
tty0 tty13 tty18 tty22 tty27 tty31 tty36 tty40 tty45 tty5 tty54 tty59 tty63 ttyS0 ttyS13 ttyS18 ttyS22 ttyS27 ttyS31 ttyS8
tty1 tty14 tty19 tty23 tty28 tty32 tty37 tty41 tty46 tty50 tty55 tty6 tty7 ttyS1 ttyS14 ttyS19 ttyS23 ttyS28 ttyS4 ttyS9
tty10 tty15 tty2 tty24 tty29 tty33 tty38 tty42 tty47 tty51 tty56 tty60 tty8 ttyS10 ttyS15 ttyS2 ttyS24 ttyS29 ttyS5
tty11 tty16 tty20 tty25 tty3 tty34 tty39 tty43 tty48 tty52 tty57 tty61 tty9 ttyS11 ttyS16 ttyS20 ttyS25 ttyS3 ttyS6
And here is my the function to initialize the serial port:
#function to initialize the serial port
def init_serial():
global ser #must be declared in each function
#set serial: port, baudrate, timeout (port does not hang)
ser = serial.Serial(port="/dev/ttyS3", baudrate=9600, timeout=5)
if ser.isOpen():
ser.close()
#open the serial port
ser.open()
#print: port is open or closed
if ser.isOpen():
print("Port open: " + ser.portstr)
else:
print("Port not open: We have a problem!")
#function ends here
I am using Ubuntu 15.04, but it also did not work on another computer using Debian.
According to ST, the STM32F0x0 line supports USB.
Edit:
As requested, the output of lsusb -v:
Bus 001 Device 003: ID 0483:3748 STMicroelectronics ST-LINK/V2
Couldn't open device, some information will be missing
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x0483 STMicroelectronics
idProduct 0x3748 ST-LINK/V2
bcdDevice 1.00
iManufacturer 1
iProduct 2
iSerial 3
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 39
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 4
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0

Answer 1

The device gets discovered and it's a ST-Link debug interface.
The STM32F0308-Discovery does not have a USB UART interface and the ST-Link does not include UART functionality as far as I can see. What you are trying to do appears to be impossible without extra hardware. You would have to get one of those USB UART interfaces with separate connectors and wire it up to the USART pins exposed on the headers.