BrianKrebsAttention Mac laptop users: It might be time to update your magsafe charger. Seriously, WTF:
https://appleinsider.com/articles/23/02/14/apple-issues-firmware-update-for-magsafe-3-charging-cable
Binder🅅@briankrebs If your cable has firmware... you might want to reevaluate your life decisions.
Charlie Stross@binder @briankrebs Every Thunderbolt 3 or 4 cable (the USB-C connector ones) has an ARM microcontroller at each end. (Not entirely sure but I think regular USB-C cables also have some variety of microcontroller to handle protocol negotiation.)
LisPi@cstross @binder @briankrebs Aren't there relatively simple resistor-based interfaces for advertising safe cable capacities without said microcontrollers?
@lispi314 USB-C does some really fancy negotiation (latest spec can deliver up to 240 watts, IIRC) and also tunnels various other protocols, eg. DisplayPort, HDMI, USB, by reassigning pins. Thunderbolt adds full-blown PCIe to the mix—it exposes a parallel bus direct to the CPU. That's in no way amenable to "simple resistor-based" negotiation.
@cstross Ah, so I must've confused it with the older USB-PD standard.
@cstross Right, those are newer additions I'll need to familiarize myself with (EPR is 2021 stuff).
https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Delivery
From the sound of it those are mostly static marker chips with most of the complex negotiation still happening between the USB controllers the cable plugs into.