I've been using Raspberry Pi Pico for some time already and I'm using minicom for serial communication. But one day Pico stopped generating tty/ATCM0 when connected to USB port. Before this everything worked perfectly fine.
I can still upload software and it's executing, but there's no serial communication because of it.
I've tried switching USB ports, uploading software that worked fine before and I even bought new Pico, as I suspected a hardware issue, but it still didn't help. My best guess is that there's something wrong with USB drivers, though I don't remember doing anything to them.
I've checked /dev for new tty files when connecting Pico, but nothing appears.
dmesg output after connecting Pico:
[ 2418.974093] usb 3-2: new full-speed USB device number 28 using xhci_hcd
[ 2434.570047] usb 3-2: device descriptor read/64, error -110 // <-- Warning
dmesg output after connecting in BOOTLOADER mode and uploading file
[ 2901.230259] usb 3-2: new full-speed USB device number 30 using xhci_hcd // <-- connected as BOOTLOADER
[ 2901.397715] usb 3-2: New USB device found, idVendor=2e8a, idProduct=0003, bcdDevice= 1.00
[ 2901.397726] usb 3-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 2901.397729] usb 3-2: Product: RP2 Boot
[ 2901.397732] usb 3-2: Manufacturer: Raspberry Pi
[ 2901.397735] usb 3-2: SerialNumber: E0C912D24340
[ 2901.399735] usb-storage 3-2:1.0: USB Mass Storage device detected
[ 2901.399885] scsi host2: usb-storage 3-2:1.0
[ 2902.412571] scsi 2:0:0:0: Direct-Access RPI RP2 1 PQ: 0 ANSI: 2
[ 2902.413038] sd 2:0:0:0: Attached scsi generic sg1 type 0
[ 2902.413315] sd 2:0:0:0: [sdb] 262144 512-byte logical blocks: (134 MB/128 MiB)
[ 2902.413731] sd 2:0:0:0: [sdb] Write Protect is off
[ 2902.413734] sd 2:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 2902.415755] sd 2:0:0:0: [sdb] No Caching mode page found // <-- Warning
[ 2902.415761] sd 2:0:0:0: [sdb] Assuming drive cache: write through // <-- Warning
[ 2902.424350] sdb: sdb1
[ 2902.427764] sd 2:0:0:0: [sdb] Attached SCSI removable disk
[ 2907.724687] usb 3-2: USB disconnect, device number 30 // <-- uploaded uf2 file
[ 2907.725456] blk_update_request: I/O error, dev sdb, sector 260 op 0x1:(WRITE) flags 0x100000 phys_seg 1 prio class 0 // <-- Warning
[ 2907.725471] Buffer I/O error on dev sdb1, logical block 259, lost async page write // <-- Warning
[ 2907.733492] FAT-fs (sdb1): unable to read boot sector to mark fs as dirty // <-- Warning
[ 2908.102068] usb 3-2: new full-speed USB device number 31 using xhci_hcd
[ 2923.530076] usb 3-2: device descriptor read/64, error -110 // <-- Warning
lsusb -tv lists these two entries only when Pico is in BOOTLOADER mode:
...
/: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
ID 1d6b:0002 Linux Foundation 2.0 root hub
|__ Port 2: Dev 35, If 0, Class=Mass Storage, Driver=usb-storage, 12M
ID 2e8a:0003
|__ Port 2: Dev 35, If 1, Class=Vendor Specific Class, Driver=, 12M
ID 2e8a:0003
...
