3 ms·

You could do what USB does and limit the current until the device signals it wants full power!

• kragen 3y ago
  a couple of levels up i said > 'super simple' excludes power negotiation schemes like usb-c like, i think you're thinking about devices one or two orders of magnitude bigger than what i'm talking about. i want to be able to wire up a 35¢ device like an attiny4 https://www.digikey.com/en/products/detail/microchip-technology/ATTINY4-TSHR/2238292 https://www.digikey.com/en/products/detail/microchip-technol... with maybe three 1¢ resistors and two 1¢ diodes for protection http://tinyurl.com/26ngjdzh http://tinyurl.com/26ngjdzh or maybe just soldered directly to the jack. it has 512 bytes of flash for the code and 32 bytes of ram; that would have to contain both whatever is necessary for the communication protocol and whatever application i want to run on it (in that case maybe it could handle a capacitive touch button or run a couple of 5-volt pwm channels) i'm not sure the attiny4 is powerful enough. but i'm pretty sure i can make the attiny45, the ch32v003, the pms150c, the attiny202, the stm8s003f3, or the mb95f264hpft work otoh in usb-c a lot of the power negotiation consists of things putting particular resistors across the line, which you could do even at that small granularity. a bus topology won't let you do that, though; if you had five devices plugged in, all their resistors would be in parallel (incidentally, despite the name, usb is not a bus; it's a bunch of point-to-point links. that's why it can do that)