[mikewarot]

I've been vibe circuit building since the 1970s, but that's not what this is about, is it? ;-)

Years ago, at Pumping Station One in Chicago, I watched someone struggle with the driving of multiple LEDs from an Arduino in his project. He wondered why the LEDs got dimmer when more than one was lit.

I looked at the original schematic, and what he had built, and noticed a difference. The original design had a resistor on each LED, but he had decided that was a redundancy and refactored it to use a single LED instead. In the case of current flow, this meant the circuit still worked, but that current limiting that resistor provided now was shared across every active LED, leading to the progressive dimming as more LEDs were active.

It turned out his background was in software, where the assumptions are much different as to what is important. Cutting out redundant code is an important skill.

I saw it as a cognitive impedance mismatch being played out in real life.

I assume the same is true for an LLM/AI attempting the same leap.

[peteforde]

I actually had this exact scenario come up last week except that in my version it warned me to make sure that I added a resistor to each LED to keep brightness normalized.

I didn't happen to need this particular advice, but it stuck in my head as something that would potentially save someone learning a lot of pain.

[quadrature]

Had this same experience back when I first learned to program a PIC microcontroller. You really shouldn't be driving LEDs directly off IO pins anyways. I think the digitalness of IO pins also lends itself to not thinking about the underlying circuitry and coming at it from a software lens.

[em3rgent0rdr]

It depends. Many modern microcontrollers are perfectly fine driving LEDs directly off IO pins if the pin specs say it is rated for sufficient current (like 20mA). However, older ones like ESP8266 can only do like 2mA and the 8051 even less. Or you run into a total power budget issue if your are running too many pins. Also, some IO pins are perfectly fine at sinking current to ground but aren't suited for sourcing current, in which case the LED would be directly connected to an external high voltage and the IO pin would simply be switching to ground or not.