Linux Tactic

Demystifying Linux I2C Tools: A Comprehensive Guide to Interfacing with I2C Devices

Linux is a popular and versatile operating system, used in a wide range of applications from servers to embedded systems. One of the many advantages of Linux is its ability to support a variety of interfaces, including the Inter-Integrated Circuit (I2C) protocol.

The I2C protocol is commonly used to connect microcontrollers and sensors to a system. As Linux is often used in embedded systems, knowing how to use I2C tools in Linux is very useful.

In this article, we will discuss the available Linux I2C tools, their commands, and how they are used.

Overview of Linux I2C Tools

Linux has several tools to work with I2C devices. These tools can be used to read and write to I2C devices, detect connected devices, and diagnose bus and slave issues.

Below are some of the commonly used Linux I2C tools. – i2c-tools: This package contains user-space tools for I2C communication.

It includes tools such as i2cdetect, i2cdump, i2cget, and i2cset. – lm-sensors: This package provides an interface for monitoring system hardware, including temperature, voltage, and fan speed.

It includes i2c sensors drivers for many popular sensors. – kernel I2C devices: Linux kernel has I2C support built-in.

This support includes I2C bus drivers, I2C chip detection, and slaves to be used by applications. The I2C bus driver provides the necessary kernel support to interact with I2C devices, while the chip detection makes sure the devices are connected to the bus correctly.

i2cdetect Command

The i2cdetect command is a part of the i2c-tools package, and it serves to detect available I2C buses and the devices connected to those buses. The syntax of the i2cdetect command is as follows.

“`

i2cdetect [-y] [-a] [-q] [-r] i2cbus [first-last]

“`

– i2cbus: This is the bus number to be scanned. – first-last: These are the optional parameters that specify the range of addresses to be scanned.

– -y: This option skips the interactive confirmation prompt. – -a: This option displays detailed information about each address.

It reads up to four bytes at the specified address and displays the result in hexadecimal format. – -q: This option suppresses output for non-existent addresses.

– -r: This option reverses the order of the scan. When the i2cdetect command is run without any options, it lists all the available I2C buses on the system.

For example, the following command lists all the available I2C buses on the system. “`

$ i2cdetect -l

“`

In most cases, there will be only one I2C bus on the system, which will be listed as i2c-0.

To scan a specific I2C bus for connected devices, run the following command. “`

$ i2cdetect -y 1

“`

This will scan the I2C bus number 1, and all the connected devices will be listed.

The output is in the form of a table, where the rows represent bus addresses, and the columns represent device addresses. The devices connected to the bus will be represented by their respective addresses.

Enquiring about Slaves Connected to a Specific Bus

Once the I2C bus is detected, we can use i2cdetect to enquire about the slaves connected to that bus. The syntax for this is:

“`

i2cdetect [-y] [-r] i2cbus

“`

– i2cbus: The bus number to be scanned.

– -r: This option displays a compact format that lists the addresses of the slaves found in hexadecimal format. To check for the slave addresses on bus 1, run the following command.

“`

$ i2cdetect -r 1

“`

This command returns a list of slaves found on the bus, with their addresses displayed in hexadecimal form. Each slave is represented by its unique address, and the corresponding row and column will be marked as “UU” in the table.

The “UU” means that the slave has been detected and acknowledged by the bus driver, but there is no driver attached to it.

Conclusion

Linux I2C tools make interfacing with I2C devices more accessible for developers and system administrators who work with hardware based on the I2C protocol. The i2cdetect command is a useful tool for detecting I2C buses and connected devices, making it easier to configure and troubleshoot systems that use I2C devices.

Other I2C tools, such as i2cget and i2cset, offer additional capabilities such as reading and writing data to I2C slaves. Overall, Linux I2C tools provide an essential set of tools that make it easier to work with I2C devices on Linux systems.

i2cget Command

The i2cget command is another tool available in the i2c-tools package in Linux. It allows us to read data from an I2C slave device connected to the system.

The i2cget command is useful in obtaining data from sensors, display data, or any other device connected to the I2C bus.

Reading from an I2C Slave Device

The syntax of the i2cget command is as follows:

“`

i2cget [-f] [-y] i2cbus chip-address data-address [mode]

“`

– i2cbus: The I2C bus number in which the device is connected. – chip-address: The I2C address of the slave device to be read.

– data-address: The internal address of the data to be read in the slave device. – -y: Bypasses the confirmation prompt.

– -f: Forces the operation even if the device is already in use by another application. – mode: The size of the data to be read.

The default mode is byte-sized (8 bits). To read data from an I2C slave device, we need to know the slave device’s address and the register or memory location of the data we want to read.

For example, the following command will read one byte of data from address 0x05 of the slave device with address 0x50 on I2C bus 1:

“`

$ i2cget -y 1 0x50 0x05

“`

This command will return the byte value of the data stored in the memory location 0x05 of the slave device with address 0x50. Reading from a 2-Byte Addressable Device with i2cget/i2cset

Some I2C devices require a 2-byte addressing scheme instead of the standard 1-byte address.

An example of such a device is the EEPROM device, which has internal addresses in two bytes. In such cases, we can use the i2cget/i2cset commands along with the -y flag to bypass the confirmation prompt.

An example of reading two bytes of data from an EEPROM device with an address of 0x50 on I2C bus 1 from internal address 0x1234 is:

“`

$ i2cget -y 1 0x50 0x12 w

“`

This command will read two bytes of data in word mode (-w) from address 0x1234 of the slave device with address 0x50 on I2C bus 1.

i2cset Command

The i2cset command is a tool available in the i2c-tools package used to write data to an I2C slave device. The i2cset command is commonly used in controlling I2C devices such as LEDs, LCD displays, DACs, and so on.

Writing to an I2C Slave Device

The syntax of the i2cset command is:

“`

i2cset [-f] [-y] i2cbus chip-address data-address value [mode]

“`

– i2cbus: The I2C bus number in which the device is connected. – chip-address: The I2C address of the slave device to write to.

– data-address: The internal address of the data to be written in the slave device. – value: The value to write to the data-address.

– -y: Bypasses the confirmation prompt. – -f: Forces the operation even if the device is already in use by another application.

– mode: The size of the data to be written. The default mode is byte-sized (8 bits).

To write data to an I2C slave device, we need to know the slave device’s address and the register where we want to write data to. For example, the following command writes a single byte value of 0x12 to the internal address 0x05 of the slave device with address 0x50 on I2C bus 1:

“`

$ i2cset -y 1 0x50 0x05 0x12

“`

This command writes a byte value of 0x12 to the memory location 0x05 of the slave device with address 0x50 on I2C bus 1.

Writing to a Specific Address of an I2C Slave Device

We can write to a specific address of an I2C slave device by providing the internal address of the data. For writable slave devices, the internal address represents the memory location to which data can be written.

For instance, writing to an EEPROM device requires the internal address of the memory location. An example of writing two bytes of data to an EEPROM with address 0x50 on I2C bus 1 is:

“`

$ i2cset -y 1 0x50 0x1234 0xAB 0xCD

“`

This command writes the byte value 0xAB to memory location 0x1234 and the byte value 0xCD to memory location 0x1235 of the slave EEPROM device with I2C address 0x50 on bus 1.

Conclusion

The use of i2cget and i2cset commands in Linux makes I2C communication easier and more efficient. These commands allow us to read from and write to I2C slave devices, making it easier to control and monitor these devices.

They can be handy in several applications, including controlling LEDs, reading from temperature sensors, and reading and writing data to EEPROMs. Overall, the i2cget and i2cset commands provide an essential toolset for developers and engineers working with I2C devices and systems.

i2cdump Command

The i2cdump command is another tool in the i2c-tools package that allows us to dump data from an I2C slave device. The i2cdump command is useful for monitoring the data stored in a device, for debugging purposes, or for making sure the data is being correctly read from or written to a device.

Dumping Data from an I2C Slave Device

The syntax of the i2cdump command is as follows:

“`

i2cdump [-f] [-y] i2cbus chip-address [mode] [start] [end]

“`

– i2cbus: The I2C bus number in which the device is connected. – chip-address: The I2C address of the slave device to dump data from.

– mode: The size of the data dump. The default mode is byte-sized (8 bits).

– start: The start address of the data to dump in the slave device. – end: The end address of the data to dump in the slave device.

– -y: Bypasses the confirmation prompt. – -f: Forces the operation even if the device is already in use by another application.

The i2cdump command is useful to dump data from an I2C slave device connected to the system. The range of data to read is defined by the start and end addresses, which can take values from 0x00 to 0xff.

For example, the following command will dump all the data stored in the slave device with address 0x50 on I2C bus 1:

“`

$ i2cdump -y 1 0x50

“`

This command reads all the data stored in the slave device with address 0x50 on I2C bus 1 and displays it on the terminal. The data is presented in hex format, with the addresses of the start of the lines and the data values on the right.

Specifying Range of Address for Data Dump

In addition to dumping all the data stored in the slave device, we can also specify the range of memory addresses to be dumped from the slave device. For instance, to dump the data stored in memory locations 0x10 to 0x20 of the slave device with address 0x50 on I2C bus 1, run the following command:

“`

$ i2cdump -y 1 0x50 0x10 b 0x20

“`

This command will dump the data stored in the memory locations 0x10 to 0x20 of the slave device with address 0x50 on I2C bus 1 and presents it in the binary format.

This range can be specified within the limits of the available memory on the slave device.

i2ctransfer Command

The i2ctransfer command is a versatile tool in the i2c-tools package that allows reading and writing of multiple bytes in a single command. i2ctransfer can combine multiple write and read operations within a single command, making it an efficient way to communicate with I2C devices that require complex commands.

Reading and Writing Multiple Bytes in the Same Command

The syntax of the i2ctransfer command for a single read or write operation is as follows:

“`

i2ctransfer [-f] [-y] [-a] [-c] [-r] i2cbus i2cmsg

“`

– i2cbus: The I2C bus number in which the device is connected. – i2cmsg: The message to send over the I2C bus.

– -y: Bypasses the confirmation prompt. – -f: Forces the operation even if the device is already in use by another application.

– -a: Sends an automatically generated stop command at the end of the message. – -c: Sends the message repeatedly, with a delay between each iteration.

– -r: Reads data back from the device. For example, the following command writes two bytes of data, 0x12 and 0x34, to the slave device with address 0x50 on I2C bus 1, and then reads two bytes of data from the same slave device:

“`

$ i2ctransfer -y -f -i 1 -d 0x50 w2:0x1234 r2

“`

This command writes 0x12 to the slave device with address 0x50 on bus 1, followed by 0x34.

It then reads back two bytes of data from the same slave device.

Reading from a 2-Byte Addressable Device with i2ctransfer

i2ctransfer is useful for reading from 2-byte addressable devices, where it can be used to specify the 2 bytes address of the device in a single command. For instance, to read two bytes of data from an EEPROM device connected to I2C bus 1 with address 0x50 and internal address 0x1234, use the following command:

“`

i2ctransfer -y -f -i 1 -s 0x50 -w w:0x1234 -r 2

“`

This command reads two bytes of data from an EEPROM device connected to I2C bus 1 with address 0x50 and internal address 0x1234.

Conclusion

i2cdump and i2ctransfer are essential tools in the i2c-tools package that significantly simplify I2C communication on Linux systems. The i2cdump command is useful when we need to debug or monitor the data stored in an I2C device, while the i2ctransfer command is useful when we need to communicate with I2C devices that require multiple read and write commands.

The i2ctransfer command can also be used to communicate with 2-byte addressable devices, making it very useful in several applications, including those involving EEPROMs.

Conclusion

In this article, we have explored the various tools available in the Linux I2C tool package, which provide a convenient and efficient way to work with I2C devices. These tools include i2cdetect, i2cget, i2cset, i2cdump, and i2ctransfer.

Each tool serves a specific purpose in allowing us to interact with I2C buses and connected slave devices. The i2cdetect command is useful for listing the available I2C buses on a Linux system and detecting the slave devices connected to those buses.

By providing the bus number as an argument, i2cdetect displays a table of addresses representing the connected devices. This command helps in identifying the devices present on the I2C bus, which is particularly useful during system setup and debugging.

The i2cget command allows us to read data from an I2C slave device. By specifying the bus number, chip address, and data address, we can retrieve specific data from the slave device.

This is beneficial for obtaining sensor data, reading from internal registers, or any other type of data stored in the slave device. Similarly, the i2cset command enables us to write data to an I2C slave device.

By providing the bus number, chip address, data address, and value, we can easily send data to the slave device. This is useful when controlling devices such as LEDs, LCD displays, or programming memory locations.

The i2cdump command allows us to dump the data stored in an I2C slave device. By specifying the bus number, chip address, and data range, we can obtain a comprehensive view of the data stored within the device.

This command is valuable for monitoring the state of a device, verifying data integrity, or troubleshooting issues. The i2ctransfer command is a versatile tool that enables us to perform read and write operations within a single command.

This is especially helpful when dealing with I2C devices that require complex command sequences or multiple transfers. The i2ctransfer command allows us to specify the bus number, send multiple write and read commands, and retrieve the data in a single operation.

This reduces the number of commands required and enhances the efficiency of I2C communication. Overall, the Linux I2C tool package provides a comprehensive and efficient set of tools for working with I2C devices.

These tools simplify the setup, configuration, and troubleshooting processes, allowing developers and system administrators to interact with I2C buses and slave devices effectively. Whether it is detecting available buses, reading from or writing to slave devices, dumping data, or performing complex read and write operations, the Linux I2C tools offer a user-friendly and powerful solution.

By leveraging the capabilities of the i2cdetect, i2cget, i2cset, i2cdump, and i2ctransfer commands, developers can easily integrate I2C devices into their Linux-based systems. Whether it is for building embedded systems, developing IoT devices, or any other application that requires I2C communication, these tools provide the necessary functionality to ensure smooth and reliable operation.

As technology continues to advance, the need for efficient and reliable communication with external devices becomes increasingly crucial. The Linux I2C tool package plays a vital role in facilitating this communication and empowers developers to work seamlessly with I2C devices.

By familiarizing themselves with these tools and understanding their capabilities, developers can harness the power of I2C communication in their Linux projects and drive innovation in various industries. In conclusion, the Linux I2C tool package offers a powerful set of tools that simplify and enhance the interaction with I2C devices.

The i2cdetect command allows for easy detection of I2C buses and connected devices, while i2cget and i2cset enable reading from and writing to I2C slave devices. The i2cdump command provides a comprehensive view of the data stored in a device, and i2ctransfer allows for efficient read and write operations.

These tools are invaluable for developers and system administrators working with I2C devices, allowing for seamless integration into Linux systems. By leveraging the capabilities of the Linux I2C tools, developers can achieve reliable and efficient communication with external I2C devices, driving innovation and advancements in various industries.

Embrace the power of Linux I2C tools, and embark on a journey of successful I2C integration in your projects.

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