[HN Gopher] I bricked my Christmas lights
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I bricked my Christmas lights
Author : willcooke
Score : 185 points
Date : 2023-12-15 18:41 UTC (4 hours ago)
(HTM) web link (www.whizzy.org)
(TXT) w3m dump (www.whizzy.org)
| willcooke wrote:
| I was trying to automate my BLE connected Christmas lights but
| instead I created e-waste. Now you can too!
| CTOSian wrote:
| you can still use them as dummy/classic lights if you bypass
| the controller
| willcooke wrote:
| +1
|
| I can just swap the micro controller with something like an
| ESP8266 and run WLED.
| green-salt wrote:
| I did this super similar (ESP32) with a set I got from
| walmart. Works great!
| wkjagt wrote:
| I find it amazing to think that your Christmas lights are
| now way more powerful than my first computer.
| sva_ wrote:
| Not sure what you did with it, but I found that some of this
| SmartTrash does a hard reset when you do some magic sequence
| such as quickly turning if off/on 5 times in a row.
| Someone wrote:
| FTA:
|
| > When we try and decrypt the on and off packets we get:
|
| > 05 54 55 52 4E 01 00 00 00 00 00 00 00 00 00 00
|
| > 05 54 55 52 4E 00 00 00 00 00 00 00 00 00 00 00
|
| > 05 54 55 52 4E 01 00 00 00 00 00 00 00 00 00 00
|
| > 05 54 55 52 4E 00 00 00 00 00 00 00 00 00 00 00
|
| > 05 54 55 52 4E 01 00 00 00 00 00 00 00 00 00 00
|
| > 05 54 55 52 4E 00 00 00 00 00 00 00 00 00 00 00
|
| > Success! This is a lot more sensible. A fixed header, byte 5
| switching between a 1 and a 0 for on and off, and a bunch of
| zeros.
|
| I would guess that's not a 'fixed header', but a length byte
| ("command is 5 bytes long"), a command ("TURN") and an argument
| (zero or one), padded with zeroes to 16 bytes.
| willcooke wrote:
| Oooh! Good spot. I will check other commands and see if that
| length idea works out. I think it could.
| EvanAnderson wrote:
| That "54 55 52 4E" jumped right out to my eye as the uppercase
| alphabet. Knowing that numbers start at 0x30, uppercase letters
| start at 0x41, and lowercase letters start at 0x61 makes
| alphanumeric patterns in hex dumps easy to spot.
|
| That knowledge is good for short strings, but the canonical
| hexdump format is a the best way to look at packet and memory
| dumps.
| ww520 wrote:
| That's a great catch. 0x54 55 52 4E indeed are T U R N.
| MarkusWandel wrote:
| Power supply failure? The WS281x things can go really bright,
| and, in bulk, suck an awful lot of current. A 12V, 3A power
| supply on a strip of 100 is just about enough to drive them all
| to full bright white, and dazzlingly bright it is. So I'd look
| for a blown fuse. The fact that the firmware only drives them to
| 31 out of a possible maximum brightness of 255 offers a clue.
| willcooke wrote:
| Good idea! I'll get the multimeter out.
| mrb wrote:
| That was my first intuition as well, seeing the brigthness
| limited to 0x1f. With any luck, the power supply might have a
| fuse, and it's just the fuse that blew up.
|
| Anyway, if you can't salvage it, standard WS281x LED strings
| can be hooked up to a Raspberry Pi and you could use my open
| source addressable LED controller :)
| https://github.com/mbevand/ledthemfight It comes with built-in
| effects. I made it very modular so for the DIY crowd, in 2
| lines of Python, you can create simple custom LED effect
| modules. See a demo here: https://youtu.be/qpd2rILsnM4
| thomasjudge wrote:
| It goes up to eleven
| nicky0 wrote:
| Icarus flew too close to the sun
| qingcharles wrote:
| But not twelve... :(
| taylodl wrote:
| Bah! Humbug!
|
| This is why I like dumb things.
| syntaxing wrote:
| Beginners question, is there a reason we can't reverse engineer
| something similar for lights made by Govee? Is it because it's
| WiFi and harder to MITM?
| steviej wrote:
| I have a couple of Govee light bulbs in my garage I control
| with an M5StickC using BLE:
| https://github.com/stevenjohnstone/reversing-tools/blob/main...
| . Looking at the decompiled Govee android app, there are many
| products with similar control over BLE in addition to wifi.
| gsharma wrote:
| The Govee strips I have do support Bluetooth connectivity. In
| fact, that's how they are setup initially.
|
| Your comment prompted me to search for "Govee LAN" and found
| HomeAssistant LAN integration. Time to dig deeper!
|
| https://www.reddit.com/r/homeassistant/s/bppM4AR3uA
| eichin wrote:
| There may be an easier way, but another HN thread pointed out
| that you can use tailscale to make it easier to tcpdump phone
| apps (because you can send all of the phone traffic through an
| endpoint you control.) (Presumably raw wireguard is enough? I
| haven't tried (or seen tutorials for) either approach, it was
| just a "that sounds clever, save it for my next sniffer
| project" idea)
| brk wrote:
| I like the form factor of some of the Govee string lights. I've
| thrown out their controller and hooked them to ESP32's with
| WLED. Best of both worlds that way.
| urbandw311er wrote:
| > Tell me how I can > break my own lights
|
| Ha! Love that.
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