December 15, 2025
Ghostbusting your living room
Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable
A $7 cable lets a Pi make your TV behave, finally
TLDR: A Raspberry Pi with a $7 HDMI cable listens to the TV’s chatter and sends the missing “wake the receiver” command, fixing flaky audio handoffs. Commenters cheer Apple TV’s reliability, debate cable vs. network automations, and reminisce about Logitech Harmony while begging for a way to also turn the TV off.
HDMI-CEC—the quirky “talking” feature inside HDMI that’s supposed to make your TV, receiver, and consoles control each other—has been ghosting people for years. One tinkerer finally exorcised it with a Raspberry Pi and a $7 cable, teaching the system to wake the receiver when a console turns on. The crowd went wild because Apple TV is the only gadget that consistently nails this dance, while PlayStations and Switches flunk the class. Cue the Apple TV teacher’s pet memes and sighs for Logitech Harmony, the universal remote that many say died too soon.
The comments split into camps: the hardware bus whisperers who love that the Pi can sit on the HDMI “party line” and watch every device’s gossip, and the network automation crowd yelling “just use Wi‑Fi and smart plugs!” baq pitched a cable-free setup with Home Assistant, while codepoet80 roasted CEC’s chaos and mourned Harmony’s demise. colechristensen confessed the first time his TV remote controlled a PS3, he thought he was hallucinating. Meanwhile, paulbgd wants the holy grail: make consoles also turn the TV off. Between jokes about ghost whisperers and ARC vs. eARC drama, the takeaway’s simple: copying whatever Apple TV does right, and firing the one missing “wake the audio” command, finally makes the living room stop acting possessed. For the curious, read up on HDMI‑CEC or peek at Homebridge and smile at the chaos we call “smart” homes.
Key Points
- •A Raspberry Pi 4 connected via a $7 micro‑HDMI to HDMI cable was used to access /dev/cec0 and monitor the HDMI-CEC bus on a receiver.
- •The setup fixed a problem where consoles switched TV inputs but did not wake the Denon AVR-X1700H to enable system audio via ARC.
- •Using cec-client, the author analyzed CEC messages and identified key opcodes (0x82, 0x84, 0x70, 0x72) and device addresses.
- •A Python script replicates Apple TV’s correct behavior by issuing the necessary command to trigger system audio, deployed as a systemd unit.
- •By bypassing HomeKit/Homebridge/Node automation layers, the solution reduced latency and reliably synchronized TV and receiver behavior.