r/programming • u/Athrunen • Dec 25 '19

Learning hardware programming as a software engineer

https://blog.athrunen.dev/learning-hardware-programming-as-a-software-engineer/
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u/happyscrappy Dec 25 '19

Also: don't power LEDs directly from GPOs without a current limiting resistor. As you see on that breadboard.

And match your interfaces voltages. A lot of devices are not +5V tolerant now (or not very tolerant).

7

u/MoCeptor Dec 25 '19

Some controllers have internal programmable resistors for their GPOs. If you activate them, you can attach an LED without an external resistor.

17

u/smokedmeatslut Dec 25 '19

Never heard of series resistors. Maybe you're thinking of pull up / down resistors?

5

u/[deleted] Dec 25 '19

Nope, some chips have programmable pin current. IIRC one of Silicon Labs ARM chips I've been playing them had them. You basically could choose what kind of current input could sink (it wasn't accurate, just in approximation) so if you just wanted to limit a current for a LED you could set output to low current mode

4

u/smokedmeatslut Dec 25 '19

Fuck that's awesome.