LED 0805 Resistor Value

Thought for 24 sec

For a 2×8 matrix = 16 LEDs, don’t drive all LEDs directly one-pin-per-LED unless you have lots of GPIO. Use a multiplexed matrix:

2 row lines
8 column lines
16 LEDs
8 current-limiting resistors, usually one per column

That uses 10 GPIO total.

Typical wiring:

Text
ROW1  ── LED LED LED LED LED LED LED LED ── columns
ROW2  ── LED LED LED LED LED LED LED LED ── columns

COL1 COL2 COL3 COL4 COL5 COL6 COL7 COL8

Use one resistor per column, e.g.:

Text
ESP32 GPIO column pin ── 150Ω to 330Ω ── LED column

Then scan rows quickly:

Enable row 1.
Set the 8 column pins for row 1 pattern.
Wait ~0.5–2 ms.
Disable row 1.
Enable row 2.
Set the 8 column pins for row 2 pattern.
Repeat forever.

For ESP32 at 3.3 V with red 0805 LEDs, I’d start with:

220 Ω if multiplexing and you want decent brightness
330 Ω for safer/lower current
470 Ω–1 kΩ if they only need to be dim indicators

Important: because each row is only on ~50% of the time, each LED appears dimmer than a continuously driven LED. You can compensate with slightly lower resistors, but keep ESP32 GPIO current limits in mind. For a clean design, use transistor/MOSFET row drivers if more than a few LEDs can be on at once.

Pick LEDs and resistors

Show LED5 schematic

Add row drivers

Compare resistor currents

Check LED5 datasheet

mixikid

can the data D+ and D- lines connecting usb c to the esp32 module have vias in their traces?

Thought for 1 sec

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