diff --git a/progress-log/2022-03-06-initial-hid-test.md b/progress-log/2022-03-06-initial-hid-test.md new file mode 100644 index 0000000..4a63927 --- /dev/null +++ b/progress-log/2022-03-06-initial-hid-test.md @@ -0,0 +1,32 @@ +# 2022-03-06 Initial HID Test + +Found a _really_ old 16gb SD card and loaded Raspbian up on it, then followed a guide to enable wifi and ssh on it before throwing it in the Pi Zero and plugging it in. After a few minutes I was able to ssh in. + +I followed a guide to enable it as a HID device, which involves adding this to `/boot/config.txt`: + +``` +dtoverlay=dwc2 +``` + +And adding this to `/etc/modules`: + +``` +dwc2 +libcomposite +``` + +Then I created the `/raspi_config/hid_usb` script that's in this repo at `/usr/bin/hid_usb` and updated `/etc/rc.local` to execute it at boot time. + +After a reboot, the Pi showed up as a usb device when running `lsusb` on the computer it's plugged into: + +``` +Bus 005 Device 008: ID 1d6b:0104 Linux Foundation Multifunction Composite Gadget +``` + +I created the `/test_scripts/test1.py` script on the Pi and ran it as root, then used a paperclip to alternately connect GPIO 26 and GPIO 16 with ground, and observed it printing characters on the host computer. 26 printed `a` over and over until I broke the connection, and 16 printed `B`. Success! + +Looking at the pin-out, there are enough GPIO inputs to support well over 6 or 9 buttons directly hand-wired, so I think that's all I need to do. I guess I'd connect one pin on each keyboard switch to ground (maybe all chained together to the same ground pin?) then the other pin from each to a distinct GPIO pin on the Pi. + +To further test this theory I got a second paper clip and awkwardly connected both GPIO 26 and 16 to the same ground pin simultaneously and observed `aBaBaBaB` being output on the host computer. Looking good! + +Done messing with the Pi today. Going to mess with OpenSCAD a bit, having just learned about it and worked through a few steps of the introductory tutorial I still have a ways to go before I'll feel comfortable designing the switch plate and case for this thing. diff --git a/test_scripts/test1.py b/test_scripts/test1.py new file mode 100755 index 0000000..43e3db7 --- /dev/null +++ b/test_scripts/test1.py @@ -0,0 +1,21 @@ +#!/usr/bin/env python3 +import time +import RPi.GPIO as GPIO + +GPIO.setmode(GPIO.BCM) +GPIO.setup(26, GPIO.IN, pull_up_down=GPIO.PUD_UP) +GPIO.setup(16, GPIO.IN, pull_up_down=GPIO.PUD_UP) + +NULL_CHAR = chr(0) + +def write_report(report): + with open('/dev/hidg0', 'rb+') as fd: + fd.write(report.encode()) + +while True: + if not(GPIO.input(26)): # 26 = a + write_report(NULL_CHAR*2+chr(4)+NULL_CHAR*5) + write_report(NULL_CHAR*8) + if not(GPIO.input(16)): # 16 = b + write_report(chr(32)+NULL_CHAR+chr(5)+NULL_CHAR*5) + write_report(NULL_CHAR*8)