A capacitor can hold enough charge to power led for noticable amount of time even if powered for a brief moment, no logic needed

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squarefoot 7 months ago | parent | next [-]

I don't think they would waste a high value capacitor just to keep a led lit for longer, also a led directly lit by a capacitor would be noticeable by slowly dimming when the capacitor discharges. It's more likely that the signal driving the led comes out of a monostable implemented in code: pin_on() drives the led on; pin_off() waits n secs then drives the led off.

	▲	altairprime 7 months ago \| parent \| next [-]
		This is Apple, so that assertion isn’t guaranteed valid like it would be for non-enterprise HP or Lenovo. They absolutely would invest in a capacitor if that’s what it takes, as they are maximally focused on camera privacy concerns and have made a point of that in their security marketing over time; or else they wouldn’t be allowing hardware security engineers to brag about it, much less talk publicly about it, at all. EDIT: It’s not just a capacitor, it’s a full custom chip, that can’t be software-modified, that keeps the light on for 3 seconds. https://news.ycombinator.com/item?id=42260379
	▲	7 months ago \| parent \| prev [-]
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HeyLaughingBoy 7 months ago | parent | prev | next [-]

Logic on an already existing ASIC is going to be cheaper than a capacitor.

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MrDrMcCoy 7 months ago | parent [-]

This is counter-intuitive enough to warrant further explanation.

	▲	ale42 7 months ago \| parent [-]
		If you are designing an ASIC for the camera, you can include all the required logic gates to control the LED for a cost that is close to zero. It wouldn't impact the production cost of the ASIC, whereas a capacitor is an additional item in the BOM (and to be charged it requires current, more than the LED, so the driver in the IC must be bigger).

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RA2lover 7 months ago | parent | prev [-]

The trick is to keep using the camera until that capacitor is discharged. I'm pretty sure most cameras can run at voltages below a LED's forward voltage nowadays.