74HC165 Shift Register (PISO)

Name: 74HC165 Shift Register (PISO)
Brand: Texas Instruments
Availability: InStock

SN74HC165

Texas Instrumentsic logic timer

The SNx4HC165 is an 8-bit parallel-load shift register that converts parallel data to serial data. It features eight parallel inputs, a serial input, and complementary serial outputs, with control for shifting or loading data.

Manufacturer datasheet

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In stock

Specifications

Operating Voltage: 2 to 6 V
Number Of Bits: 8
Interface: parallel-to-serial
Supply Current Max: 80 µA
Output Drive Current: ±4 mA
Propagation Delay Typical: 13 ns
Input Current Max: 1 µA
Clock Frequency Max: 36 MHz
Operating Temperature Range: -40 to 125 °C
Package Type: SOIC, SSOP, PDIP, SO, TSSOP

Pinout

Pin	Name	Functions	Notes
1	SH/LD	GPIO	Shift or Load input; low for parallel load, high for shifting
2	CLK	GPIO	Clock input for shifting data
3	E	GPIO	Parallel data input E
4	F	GPIO	Parallel data input F
5	G	GPIO	Parallel data input G
6	H	GPIO	Parallel data input H
7	QH	GPIO	Complementary serial data output
8	GND	GND	Ground connection
9	Q	GPIO	Serial data output
10	SER	GPIO	Serial data input
11	A	GPIO	Parallel data input A
12	B	GPIO	Parallel data input B
13	C	GPIO	Parallel data input C
14	D	GPIO	Parallel data input D
15	CLK INH	GPIO	Clock Inhibit input; high prevents output changes
16	VCC	POWER	Positive supply voltage

Interactive pinout

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SN74HC165

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Starter code

Community starter examples — minimal, unofficial, and provided to get you wiring fast. Verify against the manufacturer datasheet before relying on them.

Arduino (C++)

arduino

// 74HC165 parallel-in / serial-out shift register — community starter example
// Reads 8 inputs with shiftIn(); chain QH -> next SER for more.
#if defined(ESP32)
  #define LOAD_PIN  5    // SH/LD
  #define CLK_PIN   18   // CLK
  #define DATA_PIN  19   // QH (serial out)
#else
  #define LOAD_PIN  8
  #define CLK_PIN   7
  #define DATA_PIN  9
#endif

byte readInputs() {
  digitalWrite(LOAD_PIN, LOW);              // load parallel inputs
  digitalWrite(LOAD_PIN, HIGH);
  return shiftIn(DATA_PIN, CLK_PIN, MSBFIRST);
}

void setup() {
  Serial.begin(115200);
  pinMode(LOAD_PIN, OUTPUT);
  pinMode(CLK_PIN, OUTPUT);
  pinMode(DATA_PIN, INPUT);
}

void loop() {
  Serial.println(readInputs(), BIN);
  delay(300);
}

MicroPython

python

# 74HC165 parallel-in shift register (ESP32) — community starter example
from machine import Pin
import time

load = Pin(5, Pin.OUT)    # SH/LD
clk  = Pin(18, Pin.OUT)
data = Pin(19, Pin.IN)    # QH

def read_inputs():
    load.value(0); load.value(1)            # latch the 8 inputs
    v = 0
    for _ in range(8):
        v = (v << 1) | data.value()
        clk.value(1); clk.value(0)
    return v

while True:
    print(bin(read_inputs()))
    time.sleep(0.3)

Wiring

Pin	Arduino Uno R3	ESP32 DevKitC (WROOM-32)	Notes
VCC	+5V	3V3	2-6 V
GND	GND	GND
SH/LD	D8	GPIO5	Latch: LOW loads inputs
CLK	D7	GPIO18	Shift clock
QH	D9	GPIO19	Serial data out to the board
CLK INH	GND	GND	Tie LOW to enable clocking
A..H	-	-	8 parallel inputs (buttons/switches)

Typical uses

Reading many buttons/switches from 3 pins
Expanding inputs (chain for 16, 24, ...)