SENSORS/ACTUATORS

INTERNET OF THING (IoT)

ESP8266 - Ethernet

ESP8266 - DIP Switch

DIP (Dual In-line Package) switches find widespread use in electronics for various configuration tasks, like device addresses, communication settings, security codes. This tutorial will delve into utilizing the DIP switch with ESP8266. Specifically, we'll cover:

Understanding the DIP switch and how it works.
Establishing connections between the DIP switch and ESP8266.
Programming ESP8266 to read the ON/OFF status of the DIP switch.
Programming ESP8266 to interpret the integer values configured by the DIP switch.

Hardware Preparation

1	×	ESP8266 NodeMCU
1	×	Micro USB Cable
1	×	DIP Switch
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) Screw Terminal Expansion Board for ESP8266

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables.

Overview of DIP Switch

DIP switches are mainly used to configure devices, enabling users to adjust settings like device address, communication parameters, security codes, operation modes, and system preferences across various industries and applications.

A DIP switch consists of several small slide switches bundled together. Each of these slide switches is known as a "position." DIP switches are available in different types based on the number of positions they offer. For example, there are 2-position, 4-position, 5-position, 6-position, 8-position, and 10-position DIP switches.

A DIP switch can represent a configurable number. Each position on the switch corresponds to a bit of the number. By toggling the positions between ON and OFF, we can set the desired number we want.

Pinout

image source: diyables.io

A DIP switch is composed of two rows of pins, with the number of pins in each row matching the available switch positions. For instance, a 4-position DIP switch includes a total of 8 pins, evenly distributed with 4 pins on each side. Within the DIP switch structure, each pair of opposing pins forms a slide switch. It's worth mentioning that differentiating between pins on the two sides isn't required as they can be used interchangeably.

How It Works

IIn DIP switches, when a switch is in the ON position, it signifies that the switch is closed. This indicates that the electrical connection is established, permitting current to pass through the switch.

Conversely, when a switch is in the OFF position, it implies that the switch is open. In this state, the electrical connection is interrupted, and current cannot flow through the switch.

So, to summarize:

ON position: Closed circuit, allowing current flow.
OFF position: Open circuit, obstructing current flow.

When we connect one side of a switch to GND and the other to an ESP8266 pin, then configure the ESP8266 pin as a pull-up digital input, the table below illustrates the relationship between switch positions and the values read from the ESP8266:

DIP switch position	Binary representation	Circuit state	ESP8266 pin state
ON	1	CLOSED	LOW
OFF	0	OPEN	HIGH

In the next parts, we will use 4-position DIP switch for example. You can easily to adapt for 2-position DIP switches, 3-position DIP switches, 5-position DIP switches, 6-position DIP switches, 8-position DIP switches, and 10-position DIP switches...

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

See more in ESP8266's pinout and how to supply power to the ESP8266 and other components.

ESP8266 Code - DIP Switch

We will learn through two pieces of code:

Reading the ON/OFF state of individual position on the DIP switch.
Encoding the positions into a number.

ESP8266 code - Reading the ON/OFF state of the DIP switch

/* * This ESP8266 NodeMCU code was developed by newbiely.com * * This ESP8266 NodeMCU code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp8266/esp8266-dip-switch */ #define POSITION_NUM 4 #define ON LOW #define OFF HIGH // define the ESO8266 pins connected to the dip switch const int SWITCH_PINS[] = { D7, D6, D5, D2 }; void setup() { // initialize serial communication Serial.begin(9600); // set the dip switch pins as inputs with pull-up resistors enabled for (int i = 0; i < POSITION_NUM; i++) pinMode(SWITCH_PINS[i], INPUT_PULLUP); } void loop() { // Read the state of each switch position for (int i = 0; i < POSITION_NUM; i++) { Serial.print("position "); Serial.print(i + 1); Serial.print(": "); int state = digitalRead(SWITCH_PINS[i]); if (state == ON) Serial.println("ON "); else Serial.println("OFF "); } Serial.println(); // add a delay to prevent rapid readings delay(500); }

Detailed Instructions

To get started with ESP8266 on Arduino IDE, follow these steps:

Check out the how to setup environment for ESP8266 on Arduino IDE tutorial if this is your first time using ESP8266.
Wire the components as shown in the diagram.
Connect the ESP8266 board to your computer using a USB cable.
Open Arduino IDE on your computer.
Choose the correct ESP8266 board, such as (e.g. NodeMCU 1.0 (ESP-12E Module)), and its respective COM port.
Do wiring as above wiring diagram
Connect ESP8266 to PC via USB cable
Open Arduino IDE
Select the right board and port
Click Upload button on Arduino IDE to upload code to ESP8266
Switch each position on the DIP Switch to ON one by one.
See the result on Serial Monitor.

COM6

Send

position 1: OFF position 2: OFF position 3: OFF position 4: OFF position 1: ON position 2: OFF position 3: OFF position 4: OFF position 1: ON position 2: ON position 3: OFF position 4: OFF position 1: ON position 2: ON position 3: ON position 4: OFF position 1: ON position 2: ON position 3: ON position 4: ON

Autoscroll Show timestamp

Clear output

9600 baud

Newline

ESP8266 code - Encoding the states of DIP switch into a number

/* * This ESP8266 NodeMCU code was developed by newbiely.com * * This ESP8266 NodeMCU code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp8266/esp8266-dip-switch */ #define POSITION_NUM 4 #define ON LOW #define OFF HIGH // define the ESO8266 pins connected to the dip switch const int SWITCH_PINS[] = { D7, D6, D5, D2 }; void setup() { // Initialize serial communication Serial.begin(9600); // Set the DIP switch pins as inputs with pull-up resistors enabled for (int i = 0; i < POSITION_NUM; i++) pinMode(SWITCH_PINS[i], INPUT_PULLUP); } void loop() { int encoded_state = 0; for (int i = 0; i < POSITION_NUM; i++) { int state = digitalRead(SWITCH_PINS[i]); if (state == ON) encoded_state |= 1 << (POSITION_NUM - i - 1); } Serial.print("encoded state: "); Serial.println(encoded_state); // add a delay to prevent rapid readings delay(500); }

Detailed Instructions

To get started with ESP8266 on Arduino IDE, follow these steps:

Check out the how to setup environment for ESP8266 on Arduino IDE tutorial if this is your first time using ESP8266.
Wire the components as shown in the diagram.
Connect the ESP8266 board to your computer using a USB cable.
Open Arduino IDE on your computer.
Choose the correct ESP8266 board, such as (e.g. NodeMCU 1.0 (ESP-12E Module)), and its respective COM port.
Upload the above code to ESP8266
Switch each position on the DIP switch to ON one by one.
See the result on Serial Monitor, it look like below.

COM6

Send

encoded state: 0 encoded state: 1 encoded state: 2 encoded state: 3 encoded state: 4 encoded state: 5 encoded state: 6 encoded state: 7 encoded state: 8 encoded state: 9 encoded state: 10 encoded state: 11 encoded state: 12 encoded state: 13 encoded state: 14 encoded state: 15

Autoscroll Show timestamp

Clear output

9600 baud

Newline

Please note that the value depends on positions of each slide switches. The below table shows the mapping between ON/OFF position and the integer value for 4-position DIP switch:

Position-1	Position-2	Position-3	Position-4	Binary Value	Decimal Value
OFF	OFF	OFF	OFF	0000	0
OFF	OFF	OFF	ON	0001	1
OFF	OFF	ON	OFF	0010	2
OFF	OFF	ON	ON	0011	3
OFF	ON	OFF	OFF	0100	4
OFF	ON	OFF	ON	0101	5
OFF	ON	ON	OFF	0110	6
OFF	ON	ON	ON	0111	7
ON	OFF	OFF	OFF	1000	8
ON	OFF	OFF	ON	1001	9
ON	OFF	ON	OFF	1010	10
ON	OFF	ON	ON	1011	11
ON	ON	OFF	OFF	1100	12
ON	ON	OFF	ON	1101	13
ON	ON	ON	OFF	1110	14
ON	ON	ON	ON	1111	15

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