ESP32 NodeMCU Module - I2C Interface

The ESP32 NodeMCU module supports the I2C (Inter-Integrated Circuit) communication protocol. With its built-in hardware support for I2C, the ESP32 NodeMCU module can easily interface with various I2C devices such as sensors, displays, and other peripherals. This allows for efficient data exchange between the ESP32 and I2C devices, enabling a wide range of applications in IoT, robotics, automation, and more.

Contents

1 Pr-Request to Lean
2 ESP32 NodeMCU Module I2C Functions
3 Code of ESP32 I2C Scanner
4 Results
5 ESP32 NodeMCU I2C Interface: Code Explanation
6 Suggest
7 NEXT
- 7.1 Explore more

Pr-Request to Lean

Embedded Protocol I2C : https://aruneworld.com/embedded/embedded-protocol/i2c/

ESP32 NodeMCU Module I2C Functions

Function	Description
i2c.address()	Send (SW) or queue (HWx) I²C address and read/write mode for the next transfer.
i2c.read()	Read (SW) or queue (HWx) data for a variable number of bytes.
i2c.setup()	Initialize the I²C interface for master mode.
i2c.start()	Send (SW) or queue (HWx) an I²C start condition.
i2c.stop()	Send (SW) or queue (HWx) an I²C stop condition.
i2c.transfer()	Starts a transfer for the specified hardware module.
i2c.write()	Write (SW) or queue (HWx) data to the I²C bus.
i2c.slave.on()	Registers or unregisters an event callback handler.
i2c.slave.setup()	Initialize the I²C interface for slave mode.
i2c.slave.send()	Writes send data for the master into the transmit buffer.

Code of ESP32 I2C Scanner

In this code used to can the i2c Devices
Used Software i2c and GPIO-23 as SDA and GPIO-22 as SCL of I2C Device
Connected DS3231 Device and check i2c address of DS3231

-- setup
id  =   i2c.SW                      --  Software
pinSDA  =   23                      --  1~12, IO index
pinSCL  =   22                      --  1~12, IO index
speed   =   i2c.SLOW                    --  only i2c.SLOW supported

--Initialize
i2c.setup(id, pinSDA, pinSCL, speed)                --  Initialize the I²C module.

print("Scanning Started....")
for count = 0,127 do
  i2c.start(id)                         --  Send an I²C start condition.
  Status = i2c.address(id, count, i2c.TRANSMITTER)      --  Setup I²C address and read/write mode for the next transfer.
  i2c.stop(id)                          --  Send an I²C stop condition.
    if Status == true then
        print("Addrss - "..count.." Detected device address is  0x" .. string.format("%02x", count) .. " (" .. count ..")") 
    elseif Status == false then
        print("Addrss - "..count.." nil") 
    end
end
print("Scanning End")

Results

Scanning Started....
Addrss - 0 nil
Addrss - 1 nil
Addrss - 2 nil
Addrss - 3 nil
Addrss - 4 nil
Addrss - 5 nil
Addrss - 6 nil
Addrss - 7 nil
Addrss - 8 nil
Addrss - 9 nil
Addrss - 10 nil
Addrss - 11 nil
Addrss - 12 nil
Addrss - 13 nil
Addrss - 14 nil
Addrss - 15 nil
Addrss - 16 nil
Addrss - 17 nil
Addrss - 18 nil
Addrss - 19 nil
Addrss - 20 nil
Addrss - 21 nil
Addrss - 22 nil
Addrss - 23 nil
Addrss - 24 nil
Addrss - 25 nil
Addrss - 26 nil
Addrss - 27 nil
Addrss - 28 nil
Addrss - 29 nil
Addrss - 30 nil
Addrss - 31 nil
Addrss - 32 nil
Addrss - 33 nil
Addrss - 34 nil
Addrss - 35 nil
Addrss - 36 nil
Addrss - 37 nil
Addrss - 38 nil
Addrss - 39 nil
Addrss - 40 nil
Addrss - 41 nil
Addrss - 42 nil
Addrss - 43 nil
Addrss - 44 nil
Addrss - 45 nil
Addrss - 46 nil
Addrss - 47 nil
Addrss - 48 nil
Addrss - 49 nil
Addrss - 50 nil
Addrss - 51 nil
Addrss - 52 nil
Addrss - 53 nil
Addrss - 54 nil
Addrss - 55 nil
Addrss - 56 nil
Addrss - 57 nil
Addrss - 58 nil
Addrss - 59 nil
Addrss - 60 nil
Addrss - 61 nil
Addrss - 62 nil
Addrss - 63 nil
Addrss - 64 nil
Addrss - 65 nil
Addrss - 66 nil
Addrss - 67 nil
Addrss - 68 nil
Addrss - 69 nil
Addrss - 70 nil
Addrss - 71 nil
Addrss - 72 nil
Addrss - 73 nil
Addrss - 74 nil
Addrss - 75 nil
Addrss - 76 nil
Addrss - 77 nil
Addrss - 78 nil
Addrss - 79 nil
Addrss - 80 nil
Addrss - 81 nil
Addrss - 82 nil
Addrss - 83 nil
Addrss - 84 nil
Addrss - 85 nil
Addrss - 86 nil
Addrss - 87 Detected device address is  0x57 (87)
Addrss - 88 nil
Addrss - 89 nil
Addrss - 90 nil
Addrss - 91 nil
Addrss - 92 nil
Addrss - 93 nil
Addrss - 94 nil
Addrss - 95 nil
Addrss - 96 nil
Addrss - 97 nil
Addrss - 98 nil
Addrss - 99 nil
Addrss - 100 nil
Addrss - 101 nil
Addrss - 102 nil
Addrss - 103 nil
Addrss - 104 Detected device address is  0x68 (104)
Addrss - 105 nil
Addrss - 106 nil
Addrss - 107 nil
Addrss - 108 nil
Addrss - 109 nil
Addrss - 110 nil
Addrss - 111 nil
Addrss - 112 nil
Addrss - 113 nil
Addrss - 114 nil
Addrss - 115 nil
Addrss - 116 nil
Addrss - 117 nil
Addrss - 118 nil
Addrss - 119 nil
Addrss - 120 nil
Addrss - 121 nil
Addrss - 122 nil
Addrss - 123 nil
Addrss - 124 nil
Addrss - 125 nil
Addrss - 126 nil
Addrss - 127 nil
Scanning End
>

ESP32 NodeMCU I2C Interface: Code Explanation

This table format provides a structured breakdown of each section of the code along with its explanation.

Section	Explanation
Setup Section
id	Defines the I2C interface as software-based.
pinSDA	Specifies the GPIO pin used for the data line (SDA) of the I2C interface.
pinSCL	Specifies the GPIO pin used for the clock line (SCL) of the I2C interface.
speed	Sets the speed of the I2C communication to slow. Only `i2c.SLOW` speed is supported.
Initialization
i2c.setup()	Initializes the I2C module with the specified parameters: interface ID, SDA pin, SCL pin, and speed.
Scanning for Devices
print(“Scanning Started….”)	Prints a message indicating the start of device scanning.
Looping through device addresses	Iterates through device addresses from 0 to 127.
i2c.start()	Sends an I2C start condition.
i2c.address()	Sets up the I2C address and read/write mode for the next transfer.
i2c.stop()	Sends an I2C stop condition.
Check Status	Checks the status of the address detection: If `Status` is true, prints the detected device address in hexadecimal and decimal format. If `Status` is false, prints “nil” for the address.
print(“Scanning End”)	Prints a message indicating the end of device scanning.