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    Please do not post a support request without first reading and following the advice in https://retropie.org.uk/forum/topic/3/read-this-first

    USB HID keyboard not working in RetroPie

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    • J
      jameth
      last edited by jameth

      Hello everyone!

      I'm working on a project that has RetroPie running on a Pi Zero 2, and i was planning on using a Pi Pico to act as the "controller" by setting it up as a HID keyboard.

      This is the code I'm running on the Pico and in Raspberry PI OS it works, i ground pins on the pico, and the OS registers keypresses.

      However, I then powered down the Pi, and swapped the SD card for one with RetroPi flashed, i got to the "configure controller" prompt, grounded a pin on the pico, and nothing!

      the codes running on the Pico, an LED flashes on the Pico to indicate a key is pressed (GPIO pin grounded) but RetroPi appears to completely ignore it. if i hold down a button on my regular USB keyboard, that is detected by RetroPie.

      Im sort of amazed I have got this far, and not I'm not sure what should be the next thing to check, does anyone have experience with USB HID devices controlling a RetroPie instance? would be super grateful for any assistance :)

      Thanks!

      1 Reply Last reply Reply Quote 0
      • mituM
        mitu Global Moderator
        last edited by mitu

        Can you run the following commands and post the output:

        cat /proc/bus/input/devices
udevadm info -q all /dev/input/eventX

        (where /dev/input/eventX is the device file corresponding to your HID keyboard).

        EmulationStation uses SDL for input processing, if you can test your device with testevdev from the SDL distro (https://github.com/libsdl-org/SDL/blob/main/test/testevdev.c) that would help to determine if SDL recognizes your HID device as a keyboard or not.

        EDIT: corrected the commands.

        J 1 Reply Last reply Reply Quote 2
        • J
          jameth @mitu
          last edited by

          @mitu fantastic!!

          Thanks so much, this is exactly the sort of next step troubleshooting I was hoping to find.

          In the office today, so will get back to you tomorrow with the results.

          Thanks again!

          1 Reply Last reply Reply Quote 0
          • J
            jameth
            last edited by jameth

            OK, the OS can definitely see the HID device, but it still does not have an effect in Retropie

            @mitu quitting out of emulation station, my HID can enter text in the terminal, and it shows up with cat /proc/bus/input/devices

            I: Bus=0003 Vendor=239a Product=80f4 Version=0111
N: Name="Raspberry Pi Pico Keyboard"
P: Phys=usb-3f980000.usb-1.4/input3
S: Sysfs=/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.3/0003:239A:80F4.0003/input/input1
U: Uniq=E4620C18C3225D39
H: Handlers=sysrq kbd leds event1 
B: PROP=0
B: EV=120013
B: KEY=10000 7 ff9f207a c14057ff febeffdf ffefffff ffffffff fffffffe
B: MSC=10
B: LED=1f

I: Bus=0003 Vendor=239a Product=80f4 Version=0111
N: Name="Raspberry Pi Pico Mouse"
P: Phys=usb-3f980000.usb-1.4/input3
S: Sysfs=/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.3/0003:239A:80F4.0003/input/input2
U: Uniq=E4620C18C3225D39
H: Handlers=mouse0 event2 
B: PROP=0
B: EV=17
B: KEY=1f0000 0 0 0 0 0 0 0 0
B: REL=903
B: MSC=10

I: Bus=0003 Vendor=239a Product=80f4 Version=0111
N: Name="Raspberry Pi Pico Consumer Control"
P: Phys=usb-3f980000.usb-1.4/input3
S: Sysfs=/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.3/0003:239A:80F4.0003/input/input3
U: Uniq=E4620C18C3225D39
H: Handlers=kbd event3 
B: PROP=0
B: EV=1f
B: KEY=302ff 0 0 0 0 483ffff 17aff32d bfd44446 0 0 1 130ff3 8b17c000 677bfa d9415fed 9ed680 4400 0 10000002
B: REL=1040
B: ABS=1 0
B: MSC=10

            And then event1 returns:

            P: /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.3/0003:239A:80F4.0003/input/input1/event1
N: input/event1
L: 0
S: input/by-path/platform-3f980000.usb-usb-0:1.4:1.3-event-kbd
S: input/by-id/usb-Raspberry_Pi_Pico_E4620C18C3225D39-if03-event-kbd
E: DEVPATH=/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.3/0003:239A:80F4.0003/input/input1/event1
E: DEVNAME=/dev/input/event1
E: MAJOR=13
E: MINOR=65
E: SUBSYSTEM=input
E: USEC_INITIALIZED=7136158
E: ID_INPUT=1
E: ID_INPUT_KEY=1
E: ID_INPUT_KEYBOARD=1
E: ID_VENDOR=Raspberry_Pi
E: ID_VENDOR_ENC=Raspberry\x20Pi
E: ID_VENDOR_ID=239a
E: ID_MODEL=Pico
E: ID_MODEL_ENC=Pico
E: ID_MODEL_ID=80f4
E: ID_REVISION=0100
E: ID_SERIAL=Raspberry_Pi_Pico_E4620C18C3225D39
E: ID_SERIAL_SHORT=E4620C18C3225D39
E: ID_TYPE=hid
E: ID_BUS=usb
E: ID_USB_INTERFACES=:020200:0a0000:080650:030000:010100:010300:
E: ID_USB_INTERFACE_NUM=03
E: ID_USB_DRIVER=usbhid
E: ID_PATH=platform-3f980000.usb-usb-0:1.4:1.3
E: ID_PATH_TAG=platform-3f980000_usb-usb-0_1_4_1_3
E: LIBINPUT_DEVICE_GROUP=3/239a/80f4:usb-3f980000.usb-1
E: DEVLINKS=/dev/input/by-path/platform-3f980000.usb-usb-0:1.4:1.3-event-kbd /dev/input/by-id/usb-Raspberry_Pi_Pico_E4620C18C3225D39-if03-event-kbd
E: TAGS=:power-switch:

            so it's been detected by the OS, this immediately leaves me to believe my code running on the Pico is causing the issue.

            I have just realized that the circuit python example HID code is applying shift to every keypress, I'm going to go in now and remove the shift to see if that helps.
            edit: removing shift didn't help

            Update: I tried the HID after RetroPie had gone to "sleep" and the display dimmed, and the display woke back up, so the input is getting into Emulation Station, but the configure input tool is stubbornly refusing to register any keypresses. very odd.

            mituM 1 Reply Last reply Reply Quote 0
            • mituM
              mitu Global Moderator @jameth
              last edited by

              @jameth Just to check you're keeping the key pressed for a few seconds in the input configuration dialog, right ?
              You should also check with testevdev to see if your device is detected by SDL as a keyboard ?

              J 1 Reply Last reply Reply Quote 0
              • J
                jameth @mitu
                last edited by

                @mitu

                yeah at the configure input screen, with every other controller I have ever used, you see the type of the controller "fade in" and that happens pretty much immediately. but I have also tried holding a key pressed for several seconds.

                I also cant navigate around the Emulation station with the HID, although the HID did "wake" emulation station from its dimmed "sleep" state.

                Ill give testevdev a go after the kids gone to sleep, I'm only just about dangerous with the command line, testevdevlooks like it's written in C, so ill need to compile that before I can execute it? if you know a good tutorial that would be appreciated, but I'm sure I'll work it out.

                Thanks for all your help so far.

                mituM 1 Reply Last reply Reply Quote 0
                • mituM
                  mitu Global Moderator @jameth
                  last edited by

                  @jameth said in USB HID keyboard not working in RetroPie:

                  Ill give testevdev a go after the kids gone to sleep, I'm only just about dangerous with the command line, testevdevlooks like it's written in C, so ill need to compile that before I can execute it? if you know a good tutorial that would be appreciated, but I'm sure I'll work it out.

                  Actually, trying to produce some easy install instruction I see that testevdev doesn't actually do any live testing, just queries the system for some known devices.

                  Can you run EmulationStation with debugging enabled:

                  emulationstation --debug

                  then try to configure your input, exit and then post the log file from $HOME/.emulationstation/es_log.txt ?

                  J 1 Reply Last reply Reply Quote 1
                  • J
                    jameth @mitu
                    last edited by

                    @mitu

                    right, cracked it, everything is working as far as RetroPi is concerned.

                    Looking really closely, as I held down a HID button the word "keyboard" very very briefly appears.

                    Clearly, I was working too late the other night, I can scroll up and down a menu with my HID keyboard, I was sure I had tested that, but the output is erratic sometimes the keypress happens as I am releasing the key, sometimes a press registers as many discrete keypresses. so I think the code I am running on the pico is not cleanly emulating how a real keyboard handles button presses.

                    the log output from Debug didn't contain any mention of controller config, so I guess there were no errors there? all I saw was a long list telling me there were no ROM's for any emulators, and then a "cleanly shut down" message.

                    I'm now happy the issue is in my HID. going to find an actual keyboard project using python, and reprogramme my Pico.

                    Thanks so much for your help @mitu

                    1 Reply Last reply Reply Quote 0
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