very useful video:
https://youtu.be/wdgULBpRoXk

search for PID ACK for data packet

from keypress to PID ACK on USB line: 10 to 20ms

catting /dev/input/event0 in bash: 490us
printing via python3: 1ms

script below:

fff = open("/dev/input/event0", "rb" )
while 1:
  data = fff.read(24)
  print(data)

using queue to despatch SPI on raspberry 3: 700 to 800us
on lichee 3.5ms 

libevdev is SUPER SLOW! 20ms delay in parsing keyboard events. might write about it or do some more testing.

hand parse raw dev/input: 470us on pi3, 1ms on lichee

black PS2 extension cable both male:

purple clk
black data
brown GND

ps2 driver based on https://github.com/Harvie/ps2dev
no parity check for speed

raspberry pi gpio linux pin numbers is BCM pin number, check use `gpio readall`

in allwinner chips, linux gpio number = (position of letter in alphabet - 1) * 32 + pin number

PA3 = (1-1) * 32 + 3 = gpio3

PE3 = (5-1) * 32 + 3 = 128+3 = gpio131

echo 131 > /sys/class/gpio/export

echo in > /sys/class/gpio/gpio131/direction

cat /sys/class/gpio/gpio131/value

to see list of all interrupts
cat /proc/interrupts

change keyboard LED
sudo bash -c 'echo 1 > /sys/class/leds/input5\:\:capslock/brightness'


run script on launch:

https://raspberrypi-guide.github.io/programming/run-script-on-boot

sudo nano /etc/rc.local

cd /home/pi/usb4vc; sudo python3 usb4vc_main.py &

kill -SIGINT pid

ps2 mouse todo:

add remote mode data report
add scale/resolution change
test remote/wrap mode


supported protocols:

PS/2 Keyboard:
Scancode set 2

PS/2 Mouse:
generic id0
MS intellimouse id3

Serial Mouse:
Microsoft serial mouse (3 byte 1200bps 7n1)



rfkill returns nothing with no bluetooth on rpi 2

bluetoothctrl gets stuck if no bluetooth

check rfkill first, then put a timeout on first btctl command


bluetoothctl --agent NoInputNoOutput
scan on
trust <MAC-Address>
connect <MAC-Address>