diff --git a/libraries/74HC154/.arduino-ci.yml b/libraries/74HC154/.arduino-ci.yml
new file mode 100644
index 00000000..d9b3a2aa
--- /dev/null
+++ b/libraries/74HC154/.arduino-ci.yml
@@ -0,0 +1,30 @@
+platforms:
+  rpipico:
+    board: rp2040:rp2040:rpipico
+    package: rp2040:rp2040
+    gcc:
+      features:
+      defines:
+        - ARDUINO_ARCH_RP2040
+      warnings:
+      flags:
+
+packages:
+  rp2040:rp2040:
+    url: https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
+
+compile:
+  # Choosing to run compilation tests on 2 different Arduino platforms
+  platforms:
+    - uno
+    # - due
+    # - zero
+    # - leonardo
+    - m4
+    - esp32
+    - esp8266
+    # - mega2560
+    - rpipico
+
+  libraries:
+    - "printHelpers"
diff --git a/libraries/74HC154/.github/FUNDING.yml b/libraries/74HC154/.github/FUNDING.yml
new file mode 100644
index 00000000..90d9ab4c
--- /dev/null
+++ b/libraries/74HC154/.github/FUNDING.yml
@@ -0,0 +1,4 @@
+# These are supported funding model platforms
+
+github: RobTillaart
+
diff --git a/libraries/74HC154/.github/workflows/arduino-lint.yml b/libraries/74HC154/.github/workflows/arduino-lint.yml
new file mode 100644
index 00000000..8a26f14a
--- /dev/null
+++ b/libraries/74HC154/.github/workflows/arduino-lint.yml
@@ -0,0 +1,13 @@
+
+name: Arduino-lint
+
+on: [push, pull_request]
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: arduino/arduino-lint-action@v1
+        with:
+          library-manager: update
+          compliance: strict
diff --git a/libraries/74HC154/.github/workflows/arduino_test_runner.yml b/libraries/74HC154/.github/workflows/arduino_test_runner.yml
new file mode 100644
index 00000000..fadfa904
--- /dev/null
+++ b/libraries/74HC154/.github/workflows/arduino_test_runner.yml
@@ -0,0 +1,17 @@
+---
+name: Arduino CI
+
+on: [push, pull_request]
+
+jobs:
+  runTest:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.6
+      - run: |
+          gem install arduino_ci
+          arduino_ci.rb
diff --git a/libraries/74HC154/.github/workflows/jsoncheck.yml b/libraries/74HC154/.github/workflows/jsoncheck.yml
new file mode 100644
index 00000000..37a11298
--- /dev/null
+++ b/libraries/74HC154/.github/workflows/jsoncheck.yml
@@ -0,0 +1,18 @@
+name: JSON check
+
+on:
+  push:
+    paths:
+      - '**.json'
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: json-syntax-check
+        uses: limitusus/json-syntax-check@v1
+        with:
+          pattern: "\\.json$"
+
diff --git a/libraries/74HC154/74HC154.h b/libraries/74HC154/74HC154.h
new file mode 100644
index 00000000..4469ae76
--- /dev/null
+++ b/libraries/74HC154/74HC154.h
@@ -0,0 +1,131 @@
+#pragma once
+//
+//    FILE: 74HC154.h
+//  AUTHOR: Rob Tillaart
+//    DATE: 2024-02-22
+// VERSION: 0.1.0
+// PURPOSE: Arduino library for the 74HC154 4-to-16 line decoder/demultiplexer.
+//     URL: https://github.com/RobTillaart/74HC154
+
+
+#include "Arduino.h"
+
+#define LIB_74HC154_VERSION         (F("0.1.0"))
+
+
+
+class DEV_74HC154
+{
+public:
+  DEV_74HC154(uint8_t pin0, uint8_t pin1, uint8_t pin2, uint8_t pin3, uint8_t pinEnable = 255)
+  {
+    _pin[0] = pin0;
+    _pin[1] = pin1;
+    _pin[2] = pin2;
+    _pin[3] = pin3;
+    _enable = pinEnable;
+    _line = 0;
+
+    for (int i = 0; i < 4; i++)
+    {
+      pinMode(_pin[i], OUTPUT);
+      digitalWrite(_pin[i], LOW);
+    }
+    if (pinEnable != 255)
+    {
+      //  default disable.
+      pinMode(_enable, OUTPUT);
+      digitalWrite(_enable, HIGH);
+    }
+  }
+
+  DEV_74HC154(uint8_t * pins, uint8_t pinEnable = 255)
+  {
+    _line = 0;
+    for (int i = 0; i < 4; i++)
+    {
+      _pin[i] = pins[i];
+      pinMode(_pin[i], OUTPUT);
+      digitalWrite(_pin[i], LOW);
+    }
+    if (pinEnable != 255)
+    {
+      //  default disable.
+      pinMode(_enable, OUTPUT);
+      digitalWrite(_enable, HIGH);
+    }
+  }
+
+  //  nr == 0..15
+  bool setLine(uint8_t nr)
+  {
+    if (nr > 15) return false;
+    _line = nr;
+    _setLine();
+    return true;
+  }
+
+  uint8_t getLine()
+  {
+    return _line;
+  }
+
+  void nextLine()
+  {
+    if (_line >= 15) _line = 0;
+    else _line++;
+    _setLine();
+  }
+
+  void prevLine()
+  {
+    if (_line == 0) _line = 15;
+    else _line--;
+    _setLine();
+  }
+
+  void enable()
+  {
+    digitalWrite(_enable, LOW);
+  }
+
+  void disable()
+  {
+    digitalWrite(_enable, HIGH);
+  }
+
+  bool isEnabled()
+  {
+    return digitalRead(_enable);
+  }
+
+
+private:
+  uint8_t _pin[4];
+  uint8_t _enable = 255;
+  uint8_t _line = 0;
+
+  void _setLine()
+  {
+    digitalWrite(_pin[0], _line & 0x01);
+    digitalWrite(_pin[1], _line & 0x02);
+    digitalWrite(_pin[2], _line & 0x04);
+    digitalWrite(_pin[3], _line & 0x08);
+  }
+
+/*
+  uint8_t getLine()
+  {
+    uint8_t value = digitalRead(_pin[0]);
+    value |= digitalRead(_pin[1]) << 1;
+    value |= digitalRead(_pin[2]) << 2;
+    value |= digitalRead(_pin[3]) << 4;
+    return value;
+  };
+*/
+
+};
+
+
+//  -- END OF FILE --
+
diff --git a/libraries/74HC154/CHANGELOG.md b/libraries/74HC154/CHANGELOG.md
new file mode 100644
index 00000000..39f10735
--- /dev/null
+++ b/libraries/74HC154/CHANGELOG.md
@@ -0,0 +1,13 @@
+# Change Log DEV_74HC154
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/)
+and this project adheres to [Semantic Versioning](http://semver.org/).
+
+
+## [0.1.0] - 2024-02-23
+- initial version
+
+
+
diff --git a/libraries/74HC154/LICENSE b/libraries/74HC154/LICENSE
new file mode 100644
index 00000000..37fe70e5
--- /dev/null
+++ b/libraries/74HC154/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2024-2024 Rob Tillaart
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/libraries/74HC154/README.md b/libraries/74HC154/README.md
new file mode 100644
index 00000000..0c947a91
--- /dev/null
+++ b/libraries/74HC154/README.md
@@ -0,0 +1,91 @@
+
+[![Arduino CI](https://github.com/RobTillaart/74HC154/workflows/Arduino%20CI/badge.svg)](https://github.com/marketplace/actions/arduino_ci)
+[![Arduino-lint](https://github.com/RobTillaart/74HC154/actions/workflows/arduino-lint.yml/badge.svg)](https://github.com/RobTillaart/74HC154/actions/workflows/arduino-lint.yml)
+[![JSON check](https://github.com/RobTillaart/74HC154/actions/workflows/jsoncheck.yml/badge.svg)](https://github.com/RobTillaart/74HC154/actions/workflows/jsoncheck.yml)
+[![GitHub issues](https://img.shields.io/github/issues/RobTillaart/74HC154.svg)](https://github.com/RobTillaart/74HC154/issues)
+
+[![License: MIT](https://img.shields.io/badge/license-MIT-green.svg)](https://github.com/RobTillaart/74HC154/blob/master/LICENSE)
+[![GitHub release](https://img.shields.io/github/release/RobTillaart/74HC154.svg?maxAge=3600)](https://github.com/RobTillaart/74HC154/releases)
+[![PlatformIO Registry](https://badges.registry.platformio.org/packages/robtillaart/library/74HC154.svg)](https://registry.platformio.org/libraries/robtillaart/74HC154)
+
+
+# 74HC154
+
+Arduino library for the 74HC154 4-to-16 line decoder/demultiplexer.
+
+
+## Description
+
+This library controls the 74HC154 4 to 6 line decoder. 
+With 4 IO lines one can select one of 16 output lines. 
+
+
+#### Related
+
+- https://github.com/RobTillaart/74HC138  (3 to 8 selector)
+- https://github.com/RobTillaart/74HC154  (4 to 16 selector)
+- https://github.com/RobTillaart/HC4051  (1x8 mux)
+- https://github.com/RobTillaart/HC4052  (2x4 mux)
+- https://github.com/RobTillaart/HC4053  (3x2 mux)
+- https://github.com/RobTillaart/HC4067  (1x16 mux)
+
+
+## Interface
+
+```cpp
+#include "74HC154.h"
+```
+
+#### Constructor
+
+- **74HC154(uint8_t pin0, uint8_t pin1, uint8_t pin2, uint8_t pin3, uint8_t pinEnable = 255)** 
+set the 4 selection IO lines from pin numbers.
+Optionally set the enable pin, connect to E1 or E2, see datasheet.
+- **74HC154(uint8_t \* pins, uint8_t pinEnable = 255)** 
+set the 4 selection IO lines from an array.
+The pins array should have at least 4 elements.
+Optionally set the enable pin, connect to E1, see datasheet.
+
+
+#### Select line
+
+- **bool setLine(uint8_t line)** set line 0 .. 15. Returns false if out of range.
+- **uint8_t getLine()** returns 0 .. 15
+- **void nextLine()** selects the next line, wraps back to 0 if needed.
+- **void prevLine()** selects the previous line, wraps to 15 if needed.
+
+
+#### Enable
+
+Works only if enable line is set in constructor.
+
+- **void enable()** enables output / selection.
+- **void disable()** disables output / selection.
+- **bool isEnabled()** checks if line is enabled.
+
+
+## Future
+
+#### Must
+
+- improve documentation
+- get hardware to test
+
+#### Should
+
+
+#### Could
+
+
+#### Wont
+
+
+## Support
+
+If you appreciate my libraries, you can support the development and maintenance.
+Improve the quality of the libraries by providing issues and Pull Requests, or
+donate through PayPal or GitHub sponsors.
+
+Thank you,
+
+
diff --git a/libraries/74HC154/examples/74HC154_demo/74HC154_demo.ino b/libraries/74HC154/examples/74HC154_demo/74HC154_demo.ino
new file mode 100644
index 00000000..336f3dbe
--- /dev/null
+++ b/libraries/74HC154/examples/74HC154_demo/74HC154_demo.ino
@@ -0,0 +1,38 @@
+//
+//    FILE: 74HC154_demo.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: test basic behaviour and performance
+//     URL: https://github.com/RobTillaart/
+
+
+#include "74HC154.h"
+
+
+DEV_74HC154 selector(5, 6, 7, 8);
+
+uint8_t line = 0;
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("LIB_74HC154_VERSION: ");
+  Serial.println(LIB_74HC154_VERSION);
+
+  selector.enable();
+}
+
+
+void loop()
+{
+  Serial.println(selector.getLine());
+  delay(100);
+  selector.setLine(line);
+  line++;
+  if (line >= 16) line = 0;
+  delay(1000);
+}
+
+
+//  -- END OF FILE --
diff --git a/libraries/74HC154/examples/74HC154_night_rider/74HC154_night_rider.ino b/libraries/74HC154/examples/74HC154_night_rider/74HC154_night_rider.ino
new file mode 100644
index 00000000..53b673e1
--- /dev/null
+++ b/libraries/74HC154/examples/74HC154_night_rider/74HC154_night_rider.ino
@@ -0,0 +1,45 @@
+//
+//    FILE: 74HC154_night_rider.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: test basic behaviour and performance
+//     URL: https://github.com/RobTillaart/
+
+
+#include "74HC154.h"
+
+
+DEV_74HC154 selector(5, 6, 7, 8);
+
+uint8_t line = 0;
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("LIB_74HC154_VERSION: ");
+  Serial.println(LIB_74HC154_VERSION);
+
+  selector.enable();
+}
+
+
+void loop()
+{
+  for (int i = 0; i < 16; i++)
+  {
+    Serial.println(selector.getLine());
+    selector.nextLine();
+    delay(100);
+  }
+  for (int i = 0; i < 16; i++)
+  {
+    Serial.println(selector.getLine());
+    selector.prevLine();
+    delay(100);
+  }
+
+}
+
+
+//  -- END OF FILE --
diff --git a/libraries/74HC154/examples/74HC154_prev_next/74HC154_prev_next.ino b/libraries/74HC154/examples/74HC154_prev_next/74HC154_prev_next.ino
new file mode 100644
index 00000000..44f31fc2
--- /dev/null
+++ b/libraries/74HC154/examples/74HC154_prev_next/74HC154_prev_next.ino
@@ -0,0 +1,45 @@
+//
+//    FILE: 74HC154_prev_next.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: test basic behaviour and performance
+//     URL: https://github.com/RobTillaart/74HC154
+
+
+#include "74HC154.h"
+
+
+DEV_74HC154 selector(5, 6, 7, 8);
+
+uint8_t line = 0;
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("LIB_74HC154_VERSION: ");
+  Serial.println(LIB_74HC154_VERSION);
+
+  selector.enable();
+}
+
+
+void loop()
+{
+  for (int i = 0; i < 30; i++)
+  {
+    Serial.println(selector.getLine());
+    selector.nextLine();
+    delay(100);
+  }
+  for (int i = 0; i < 30; i++)
+  {
+    Serial.println(selector.getLine());
+    selector.prevLine();
+    delay(100);
+  }
+
+}
+
+
+//  -- END OF FILE --
diff --git a/libraries/74HC154/keywords.txt b/libraries/74HC154/keywords.txt
new file mode 100644
index 00000000..8f1c2370
--- /dev/null
+++ b/libraries/74HC154/keywords.txt
@@ -0,0 +1,20 @@
+# Syntax Colouring Map For DEV_74HC154
+
+# Data types (KEYWORD1)
+DEV_74HC154	KEYWORD1
+
+
+# Methods and Functions (KEYWORD2)
+setLine	KEYWORD2
+getLine	KEYWORD2
+nextLine	KEYWORD2
+prevLine	KEYWORD2
+
+enable	KEYWORD2
+disable	KEYWORD2
+isEnabled	KEYWORD2
+
+
+# Constants (LITERAL1)
+LIB_74HC154_VERSION	LITERAL1
+
diff --git a/libraries/74HC154/library.json b/libraries/74HC154/library.json
new file mode 100644
index 00000000..b9da30b6
--- /dev/null
+++ b/libraries/74HC154/library.json
@@ -0,0 +1,23 @@
+{
+  "name": "74HC154",
+  "keywords": "3 to 8",
+  "description": "Arduino library for the 74HC154 4-to-16 line decoder/demultiplexer.",
+  "authors":
+  [
+    {
+      "name": "Rob Tillaart",
+      "email": "Rob.Tillaart@gmail.com",
+      "maintainer": true
+    }
+  ],
+  "repository":
+  {
+    "type": "git",
+    "url": "https://github.com/RobTillaart/74HC154.git"
+  },
+  "version": "0.1.0",
+  "license": "MIT",
+  "frameworks": "*",
+  "platforms": "*",
+  "headers": "74HC154.h"
+}
diff --git a/libraries/74HC154/library.properties b/libraries/74HC154/library.properties
new file mode 100644
index 00000000..c95be378
--- /dev/null
+++ b/libraries/74HC154/library.properties
@@ -0,0 +1,11 @@
+name=74HC154
+version=0.1.0
+author=Rob Tillaart <rob.tillaart@gmail.com>
+maintainer=Rob Tillaart <rob.tillaart@gmail.com>
+sentence=Arduino library for the 74HC154 4 to 16 line decoder/demultiplexer.
+paragraph=
+category=Sensors
+url=https://github.com/RobTillaart/74HC154
+architectures=*
+includes=74HC154.h
+depends=
diff --git a/libraries/74HC154/test/unit_test_001.cpp b/libraries/74HC154/test/unit_test_001.cpp
new file mode 100644
index 00000000..ae8d66a7
--- /dev/null
+++ b/libraries/74HC154/test/unit_test_001.cpp
@@ -0,0 +1,83 @@
+//
+//    FILE: unit_test_001.cpp
+//  AUTHOR: Rob Tillaart
+//    DATE: 2024-02-23
+// PURPOSE: unit tests for the 74HC154 library
+//     URL: https://github.com/RobTillaart/74HC154
+//
+
+// supported assertions
+// https://github.com/Arduino-CI/arduino_ci/blob/master/cpp/unittest/Assertion.h#L33-L42
+// ----------------------------
+// assertEqual(expected, actual)
+// assertNotEqual(expected, actual)
+// assertLess(expected, actual)
+// assertMore(expected, actual)
+// assertLessOrEqual(expected, actual)
+// assertMoreOrEqual(expected, actual)
+// assertTrue(actual)
+// assertFalse(actual)
+// assertNull(actual)
+// assertNotNull(actual)
+
+#include <ArduinoUnitTests.h>
+
+
+#include "74HC154.h"
+
+
+unittest_setup()
+{
+  fprintf(stderr, "LIB_74HC154_VERSION: %s\n", (char *) LIB_74HC154_VERSION);
+}
+
+
+unittest_teardown()
+{
+}
+
+
+unittest(test_setLine)
+{
+  DEV_74HC154 dev(5, 6, 7, 8);
+
+  for (int i = 0; i < 16; i++)
+  {
+    assertTrue(dev.setLine(i));
+    assertEqual(i, dev.getLine());
+  }
+  assertFalse(dev.setLine(16));
+}
+
+
+unittest(test_nextLine)
+{
+  DEV_74HC154 dev(5, 6, 7, 8);
+
+  assertTrue(dev.setLine(0));
+  for (int i = 0; i < 16; i++)
+  {
+    assertEqual(i, dev.getLine());
+    dev.nextLine();
+  }
+}
+
+
+unittest(test_prevLine)
+{
+  DEV_74HC154 dev(5, 6, 7, 8);
+
+  assertTrue(dev.setLine(15));
+  for (int i = 15; i > 0; i--)
+  {
+    assertEqual(i, dev.getLine());
+    dev.prevLine();
+  }
+}
+
+
+unittest_main()
+
+
+//  -- END OF FILE --
+