Arduino I2C Tester

Scans for I2C devices and performs read/write operations based on commands from the Serial Monitor.

Arduino Nano standard I2C connection

• ⚪ White: A4 - SDA
• 🟡 Yellow: A5 - SCL
• ⚫ Black: GND

Supported commands

• scan - checks for connected devices.
• connect - checks if a device is available at the specified address. If it is, the address is saved and used for further data exchange.
• write byte - sends one byte to a device.
• read bytes - requests a specified number of bytes from the device.

Common Use Cases

Case 1. Scan and Connect

1. Open Serial Monitor:

===============================================
I2C Tester
- scan
- connect
- write byte
- read bytes
===============================================
Input command: 

2. Enter scan:

Input command: `scan`
Scanning...
I2C device found at address: 0x55
Done.

3. Enter connect:

Input command: `connect`
Input address, or press Enter (leave empty) to exit: 

4. Enter 0x55:

Input command: `connect`
Input address, or press Enter (leave empty) to exit: 0x55
Connecting to: 0x55
Connection successful.

Executing the connect command is optional - if no address has been saved, the program will automatically prompt you to enter one before any read or write operation.

Case 2. Write/Read Bytes

1. Enter write byte
2. Enter 0x08 - for example, the Voltage() command of the BQ28Z610 Gas Gauge Device:

Input command: `write byte`
Input byte value to write, or press Enter (leave empty) to exit: 0x08
Writing byte 0x08 to 0x55
ok

3. Enter read bytes:

Input command: `read bytes`
Input number of bytes to read, press Enter (leave empty) for 1:

4. Enter 2 to read a word:

Input command: `read bytes`
Input number of bytes to read, press Enter (leave empty) for 1: 2
Reading 2 byte(s) from 0x55:
[ C9 1A ]
Actual read: 2

5. [ C9 1A ] = 0x1AC9 (Little Endian) = 6857 (mV)

Case 3. Working with Registers

As an example, here is the sequence for reading the Chemical ID of the BQ28Z610 device:

1. write byte
2. 0x3e or 0x00

Input command: `write byte`
Input byte value to write, or press Enter (leave empty) to exit: 0x00
Writing byte 0x00 to 0x55
ok

3. write byte
4. 0x06

Input command: `write byte`
Input byte value to write, or press Enter (leave empty) to exit: 0x06
Writing byte 0x06 to 0x55
ok

5. write byte
6. 0x00

Input command: `write byte`
Input byte value to write, or press Enter (leave empty) to exit: 0x00
Writing byte 0x00 to 0x55
ok

7. write byte
8. 0x3e

Input command: `write byte`
Input byte value to write, or press Enter (leave empty) to exit: 0x3e
Writing byte 0x3e to 0x55
ok

9. read bytes
10. 36

Input command: `read bytes`
Input number of bytes to read, press Enter (leave empty) for 1: 36
Reading 36 byte(s) from 0x55:
[ 06 00 52 13 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 94 06 ]
Actual read: 36

Where:

• 06 00 - Input Command 0x0006 (for verification)
• 52 13 = ChemID 1352
• last two bytes 94 06:
  • 0x94 - checksum: 0x94 = 0xFF - (0x06 + 0x00 + 0x52 + 0x13)
  • 0x06 - length: two bytes for command, two bytes for result, two bytes for checksum and length

Author

@asilichenko

License

MIT license

Sources

• i2c_tester.ino - main Arduino sketch
• utils.h - util functions header
• utils.cpp - util function implementation

See Also

• Custom Driver for Gas Gauging Device BQ28Z610 - A driver for Arduino that provides functions to interface with the BQ28Z610 battery gas gauge device over I2C protocol.
• JBL XTREME 2 BMS - Arduino sketches to analyse and emulate BMS microchip of the Battery Pack for the JBL XTREME 2 Bluetooth Speaker.