moritzmhmk/CEC_Pi_zero.md

## CEC_Pi_zero.md

      
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              CEC_Pi_zero.md
            
          
    Faking HDMI Port

echo "pa 30 00" | cec-client
sets physical address to 3.0.0.0 - which is HDMI Port 3 - receiving remote control signals from different hdmi port
Use Pi zero as "Pulse8 CEC Adapter"

Enable USB Serial

/boot/config.txt add dtoverlay=dwc2
/boot/cmdline.txt add modules-load=dwc2 (not dwc2,g_serial - see below)
Fake the VendorID and ProductID

To fake the VendorID and ProductID to match those of the usb adapter one cant use the default "g_serial" module.
Alternative method found here
#!/bin/bash -e

modprobe libcomposite

cd /sys/kernel/config/usb_gadget/
mkdir g && cd g

echo 0x2548 > idVendor  # pulse-8
echo 0x1001 > idProduct # Multifunction Composite Gadget
echo 0x0100 > bcdDevice # v1.0.0
echo 0x0200 > bcdUSB    # USB 2.0

mkdir -p strings/0x409
echo "deadbeef00115599" > strings/0x409/serialnumber
echo "irq5 labs"        > strings/0x409/manufacturer
echo "Pi Zero Gadget"   > strings/0x409/product

mkdir -p functions/acm.usb0    # serial
# mkdir -p functions/rndis.usb0  # network

mkdir -p configs/c.1
echo 250 > configs/c.1/MaxPower
# ln -s functions/rndis.usb0 configs/c.1/
ln -s functions/acm.usb0   configs/c.1/

udevadm settle -t 5 || :
ls /sys/class/udc/ > UDC
Check that it is working

use cat /dev/ttyGS0 (or xxd /dev/ttyGS0 for hex output) to show received messages.
send messages by calling echo "foo" > /dev/ttyGS0 (or echo -n -e '\x66\x6f\x6f' > /dev/ttyGS0 for hex input)
Install a cec-client on the host

for macOS use Couch Slouch
check communication with above commands
Respond to received messages

pulse8 protocol
To be continued ...