Comment by nippoo
6 hours ago
eFuses have been a thing forever on almost all MCUs/processors, and aren't some inherently "evil" technology - mostly they're used in manufacturing when you might have the same microcontroller/firmware on separate types of boards. I'm working on a board right now which is either an audio input or an output (depending on which components are fitted) and one or the other eFuse is burned to set which one it is, so subsequent firmware releases won't accidentally set a GPIO as an output rather than an input and potentially damage the device.
Isn't this normally done with a GPIO bootstrap?
It depends. Usually there are enough "knobs" that adding that many balls to the package would be crazy expensive at volume.
Most SoCs of even moderate complexity have lots of redundancy built in for yield management (e.x. anything with RAM expects some % of the RAM cells to be dead on any given chip), and uses fuses to keep track of that. If you had to have a strap per RAM block, it would not scale.