RPi Zero keyboard test

configfs_test.sh

#!/bin/bash

sleep 15

# Create gadget
mkdir /sys/kernel/config/usb_gadget/mykeyboard
cd /sys/kernel/config/usb_gadget/mykeyboard

# Add basic information
echo 0x0100 > bcdDevice # Version 1.0.0
echo 0x0200 > bcdUSB # USB 2.0
echo 0x00 > bDeviceClass
echo 0x00 > bDeviceProtocol
echo 0x00 > bDeviceSubClass
echo 0x08 > bMaxPacketSize0
echo 0x0104 > idProduct # Multifunction Composite Gadget
echo 0x1d6b > idVendor # Linux Foundation

# Create English locale
mkdir strings/0x409

echo "My manufacturer" > strings/0x409/manufacturer
echo "My virtual keyboard" > strings/0x409/product
echo "0123456789" > strings/0x409/serialnumber

# Create HID function
mkdir functions/hid.usb0

echo 1 > functions/hid.usb0/protocol
echo 8 > functions/hid.usb0/report_length # 8-byte reports
echo 1 > functions/hid.usb0/subclass

# Write report descriptor
echo "05010906a101050719e029e71500250175019508810275089501810175019503050819012903910275019505910175089506150026ff00050719002aff008100c0" | xxd -r -ps > functions/hid.usb0/report_desc

# Create configuration
mkdir configs/c.1
mkdir configs/c.1/strings/0x409

echo 0x80 > configs/c.1/bmAttributes
echo 200 > configs/c.1/MaxPower # 200 mA
echo "Example configuration" > configs/c.1/strings/0x409/configuration

# Link HID function to configuration
ln -s functions/hid.usb0 configs/c.1

# Enable gadget
ls /sys/class/udc > UDC

sleep 15

/usr/local/bin/tester.sh &
# /usr/local/bin/tester.py &

tester.py

#!/usr/bin/env python3
#
# Python file to test the gadget by writing "Hello World!"
# If used with the configfs_test.sh, place this file under /usr/local/bin/tester.py
# and uncomment the appropriate line

NULL_CHAR = chr(0)

def write_report(report):
    with open('/dev/hidg0', 'rb+') as fd:
        fd.write(report.encode())


# H (press shift and H)
write_report(chr(32)+NULL_CHAR+chr(11)+NULL_CHAR*5)

# e
write_report(NULL_CHAR*2+chr(8)+NULL_CHAR*5)

# ll
write_report(NULL_CHAR*2+chr(15)+NULL_CHAR*5)
write_report(NULL_CHAR*8)
write_report(NULL_CHAR*2+chr(15)+NULL_CHAR*5)

# o
write_report(NULL_CHAR*2+chr(18)+NULL_CHAR*5)

# SPACE
write_report(NULL_CHAR*2+chr(44)+NULL_CHAR*5)

# W (press shift and W)
write_report(chr(32)+NULL_CHAR+chr(26)+NULL_CHAR*5)

# o
write_report(NULL_CHAR*2+chr(18)+NULL_CHAR*5)

# r
write_report(NULL_CHAR*2+chr(21)+NULL_CHAR*5)

# l
write_report(NULL_CHAR*2+chr(15)+NULL_CHAR*5)

# d
write_report(NULL_CHAR*2+chr(7)+NULL_CHAR*5)

# ! (press shift and 1)
write_report(chr(32)+NULL_CHAR+chr(30)+NULL_CHAR*5)

# Release all keys
write_report(NULL_CHAR*8)

tester.sh

#!/bin/bash
#
# Bash file to test the gadget by writing "Hello World!"
# If used with the configfs_test.sh, place this file under /usr/local/bin/tester.sh
# and uncomment the appropriate line

function write_report {
    echo -ne $1 > /dev/hidg0
}

# H (press shift and H)
write_report "\x20\0\xb\0\0\0\0\0"

# e
write_report "\0\0\x8\0\0\0\0\0"

# ll
write_report "\0\0\xf\0\0\0\0\0"
write_report "\0\0\0\0\0\0\0\0"
write_report "\0\0\xf\0\0\0\0\0"

# o
write_report "\0\0\x12\0\0\0\0\0"

# SPACE
write_report "\0\0\x2c\0\0\0\0\0"

# W (press shift and W)
write_report "\x20\0\x1a\0\0\0\0\0"

# o
write_report "\0\0\x12\0\0\0\0\0"

# r
write_report "\0\0\x21\0\0\0\0\0"

# l
write_report "\0\0\xf\0\0\0\0\0"

# d
write_report "\0\0\x7\0\0\0\0\0"

# ! (press shift and 1)
write_report "\x20\0\x1e\0\0\0\0\0"

# Release al keys
write_report "\0\0\0\0\0\0\0\0"

not sure if this is my case only
tester.sh - line 34 ~ 35

# r
write_report "\0\0\x21\0\0\0\0\0"

this report typed "4" instead of "r"

so I changed that 21 to 15 and works fine for me

(Reference: https://usb.org/sites/default/files/hut1_21.pdf Chaprter 10)

Hello @rmed, thanks for the blog post, it's the most clearer about HID with RPi Zero that I ever saw.

@flash76 Seems like the device already exists when you try to execute the script. Is there any gadget preconfigured in the RPi (e.g. ethernet over USB)?

Related to this, I'm trying to use a RPi Zero (not the W), but to have access to the terminal, I need to use the data micro USB, and I'm having the same problem that @flash76 had about the resource being busy, do you have any way that I could make it happen?

I don't know if this is related. I added "chown pi /dev/hidg0" at the end of the startup script so that the device is available to the regular user "pi".