74HC595 shift register with ESP32 DevKit V1 — 3.3 V, hardware SPI, PWM dimming

A 74HC595 turns three GPIOs into eight outputs, and chained chips give you as many as you like. It is how people drive LED bar graphs, 7-segment displays and big LED matrices from one board.

On the ESP32 DevKit V1 the chip runs from 3V3, so its inputs match the ESP32’s 3.3 V logic. Data and clock come from the VSPI hardware (D23 and D18), the latch is on D4, and the active-LOW OE pin is driven with PWM from D32 so all eight LEDs fade together. A 10 kΩ pull-up on OE keeps them dark while the ESP32 boots.

Wiring

Also needed: 8 LEDs and 8 × 220 Ω resistors, 10 kΩ resistor (OE pull-up), 100 nF ceramic capacitor.

Every connection
ESP32 DevKit V1	74HC595 8-bit shift register (DIP-16)	Wire	Notes
—	Q0	—	To LED 1 via 220 Ω to GND (not drawn)
—	Q1	—	To LED 2 via 220 Ω (not drawn)
—	Q2	—	To LED 3 via 220 Ω (not drawn)
—	Q3	—	To LED 4 via 220 Ω (not drawn)
—	Q4	—	To LED 5 via 220 Ω (not drawn)
—	Q5	—	To LED 6 via 220 Ω (not drawn)
—	Q6	—	To LED 7 via 220 Ω (not drawn)
—	Q7	—	To LED 8 via 220 Ω (not drawn)
3V3	VCC	red	Pin 16. Powering the chip from 3.3 V makes its inputs match the ESP32’s logic. 100 nF capacitor from VCC to GND at the chip.
GND	GND	black	Pin 8.
D23	DS	green	Pin 14, serial data (VSPI MOSI).
D18	SH_CP	blue	Pin 11, shift clock (VSPI SCK).
D4	ST_CP	yellow	Pin 12, latch.
D32	OE	purple	Pin 13, active-LOW output enable, driven with PWM for brightness.
3V3	OE	red	Via 10 kΩ — Pull-up: holds the outputs off while the ESP32 boots and D32 is still floating.
3V3	MR	red	Pin 10, active-LOW reset — keep HIGH.

2–6 V part, 3.3 V board. Power it from the same voltage as your board: 3.3 V on ESP32 and Pico, 5 V on Uno. At 5 V the 74HC595 needs about 3.15 V for a HIGH, so a 3.3 V board driving a 5 V-powered chip is marginal — use a 74HCT595 at 5 V for that.

Board quirks

Power the 74HC595 from 3V3, not VIN. At 5 V the chip needs about 3.5 V for a HIGH, so 3.3 V signals are marginal. At 3.3 V everything matches; if you need 5 V outputs (for example to drive a 5 V relay board), use a 74HCT595 on 5 V instead.
At 3.3 V each output drives less current, so this guide uses 220 Ω resistors (about 5–6 mA per red LED). Keep the total under the chip’s 70 mA limit when all eight are on.
Data and clock use the VSPI hardware at 8 MHz — hundreds of times faster than shiftOut(), which matters when you chain many chips for a big LED display. SPI.begin(18, -1, 23, -1) leaves MISO (D19) free because the 595 never sends data back.
ESP32 GPIOs float for a moment at power-on, so the 10 kΩ pull-up on OE keeps the LEDs dark until the sketch has loaded known data. Without it you may see a random flash at every reset.
analogWrite() works on the ESP32 in core 3.x (it uses the LEDC peripheral). OE is active-LOW, so the sketch writes 255 − brightness.
Chain more chips by wiring Q7S (pin 9) to the next chip’s DS and sharing SH_CP, ST_CP and OE. Then send one byte per chip, last chip first.

Code

74hc595-esp32.inoArduino C++Open in Playground Flash

// 74HC595 shift register on an ESP32 DevKit V1 — hardware SPI plus PWM brightness on OE.
// VCC → 3V3, GND → GND, DS → D23 (VSPI MOSI), SH_CP → D18 (VSPI SCK), ST_CP (latch) → D4,
// OE → D32 (PWM) with a 10 kΩ pull-up to 3V3, MR → 3V3. Q0–Q7 → LED + 220 Ω each → GND.
#include <SPI.h>

constexpr uint8_t SCK_PIN = 18, MOSI_PIN = 23, LATCH_PIN = 4, OE_PIN = 32;

void writeByte(uint8_t value) {
  SPI.beginTransaction(SPISettings(8000000, MSBFIRST, SPI_MODE0));  // 8 MHz: far faster than shiftOut()
  SPI.transfer(value);                                              // Q7 gets the first bit sent
  SPI.endTransaction();
  digitalWrite(LATCH_PIN, HIGH);  // rising edge copies the 8 bits to Q0–Q7 together
  digitalWrite(LATCH_PIN, LOW);
}

// OE is active LOW, so a brighter LED needs a lower duty on OE.
void brightness(uint8_t level) { analogWrite(OE_PIN, 255 - level); }

void setup() {
  pinMode(OE_PIN, OUTPUT);
  digitalWrite(OE_PIN, HIGH);  // outputs off until the register holds known data
  pinMode(LATCH_PIN, OUTPUT);
  digitalWrite(LATCH_PIN, LOW);
  SPI.begin(SCK_PIN, -1, MOSI_PIN, -1);  // no MISO: the 74HC595 never talks back, D19 stays free
  writeByte(0);
  brightness(255);
  Serial.begin(115200);
  Serial.println("74HC595 on VSPI: running light, then a breathing bar");
}

void loop() {
  for (uint8_t i = 0; i < 8; i++) {
    writeByte(1 << i);
    delay(70);
  }
  for (int8_t i = 6; i > 0; i--) {
    writeByte(1 << i);
    delay(70);
  }
  writeByte(0xFF);
  Serial.println("All on, fading with PWM on OE");
  for (int l = 255; l >= 0; l -= 5) {
    brightness(l);
    delay(15);
  }
  for (int l = 0; l <= 255; l += 5) {
    brightness(l);
    delay(15);
  }
  Serial.println("Pattern 0b10101010 = 170");
  writeByte(0b10101010);
  delay(600);
}

// 74HC595 shift register on an ESP32 DevKit V1 — hardware SPI plus PWM brightness on OE.
// VCC → 3V3, GND → GND, DS → D23 (VSPI MOSI), SH_CP → D18 (VSPI SCK), ST_CP (latch) → D4,
// OE → D32 (PWM) with a 10 kΩ pull-up to 3V3, MR → 3V3. Q0–Q7 → LED + 220 Ω each → GND.
#include <SPI.h>

constexpr uint8_t SCK_PIN = 18, MOSI_PIN = 23, LATCH_PIN = 4, OE_PIN = 32;

void writeByte(uint8_t value) {
  SPI.beginTransaction(SPISettings(8000000, MSBFIRST, SPI_MODE0));  // 8 MHz: far faster than shiftOut()
  SPI.transfer(value);                                              // Q7 gets the first bit sent
  SPI.endTransaction();
  digitalWrite(LATCH_PIN, HIGH);  // rising edge copies the 8 bits to Q0–Q7 together
  digitalWrite(LATCH_PIN, LOW);
}

// OE is active LOW, so a brighter LED needs a lower duty on OE.
void brightness(uint8_t level) { analogWrite(OE_PIN, 255 - level); }

void setup() {
  pinMode(OE_PIN, OUTPUT);
  digitalWrite(OE_PIN, HIGH);  // outputs off until the register holds known data
  pinMode(LATCH_PIN, OUTPUT);
  digitalWrite(LATCH_PIN, LOW);
  SPI.begin(SCK_PIN, -1, MOSI_PIN, -1);  // no MISO: the 74HC595 never talks back, D19 stays free
  writeByte(0);
  brightness(255);
  Serial.begin(115200);
  Serial.println("74HC595 on VSPI: running light, then a breathing bar");
}

void loop() {
  for (uint8_t i = 0; i < 8; i++) {
    writeByte(1 << i);
    delay(70);
  }
  for (int8_t i = 6; i > 0; i--) {
    writeByte(1 << i);
    delay(70);
  }
  writeByte(0xFF);
  Serial.println("All on, fading with PWM on OE");
  for (int l = 255; l >= 0; l -= 5) {
    brightness(l);
    delay(15);
  }
  for (int l = 0; l <= 255; l += 5) {
    brightness(l);
    delay(15);
  }
  Serial.println("Pattern 0b10101010 = 170");
  writeByte(0b10101010);
  delay(600);
}

Expected serial output

Serial Monitor · 115200Output

74HC595 on VSPI: running light, then a breathing bar
All on, fading with PWM on OE
Pattern 0b10101010 = 170

74HC595 on VSPI: running light, then a breathing bar
All on, fading with PWM on OE
Pattern 0b10101010 = 170

Common errors

LEDs flash randomly at every reset

The OE pull-up is missing. Add 10 kΩ from OE to 3V3.

Nothing lights

MR is LOW or floating (tie it to 3V3), or the latch on D4 isn’t connected. Without a rising edge on ST_CP the outputs never change.

LEDs are very dim

Check the resistor values, and that the chip is a 74HC595 and not a 74HCT595 on 3.3 V (HCT parts are specified for 5 V).