I2C

Functionality overview

I2C commands enable communication with I2C devices connected to Red Pitaya’s extension connector. Control I2C bus initialization, device addressing, read/write operations, and clock stretching for interfacing with sensors, EEPROMs, and other I2C peripherals.

Important notes

  • I2C device path may vary between board models.

  • Device addresses are specified in 7-bit format (not including R/W bit).

  • Clock stretching support depends on connected device capabilities.

  • Use force mode carefully as it can interfere with devices in use.

Code examples

Here are some examples of how to use I2C communication:

Parameters and command table

Parameter options:

  • <mode> = {OFF, ON} Default: OFF

  • <value> = {XXX | #HXX | #QXXX | #BXXXXXXXX} Value in Decimal, Hexadecimal, Octal, or Binary format.

  • <data> = {XXX, ... | #HXX, ... | #QXXX, ... | #BXXXXXXXX, ... } Array of data values separated by commas.

    • XXX = Dec format

    • #HXX = Hex format

    • #QXXX = Oct format

    • #BXXXXXXXX = Bin format

SCPI

API, Jupyter

DESCRIPTION

ECOSYSTEM
I2C:DEV<addr> <path>
Example:
I2C:DEV80 "/dev/i2c-0"
C++: rp_I2C_InitDevice(const char *device, uint8_t addr)

Python: rp_I2C_InitDevice(<device>, <addr>)
Initializes settings for I2C.
- <path> - Path to the I2C device.
- <addr> - Device address on the I2C bus in dec format.

1.04-18 and up
I2C:DEV? > <addr>
Example:
I2C:DEV? > 80
C++: rp_I2C_getDevAddress(int *address)

Python: rp_I2C_getDevAddress()

Returns the current address of the device.

1.04-18 and up
I2C:FMODE <mode>
Example:
I2C:FMODE ON
C++: rp_I2C_setForceMode(bool force)

Python: rp_I2C_setForceMode(<force>)

Enables forced bus operation even if the device is in use.

1.04-18 and up
I2C:FMODE? > <mode>
Example:
I2C:FMODE? > ON
C++: rp_I2C_getForceMode(bool *value)

Python: rp_I2C_getForceMode()

Gets the current forced mode setting.

1.04-18 and up
I2C:Smbus:Read<reg>? > <value>
Example:
I2C:Smbus:Read2? > 0
C++: rp_I2C_SMBUS_Read(uint8_t reg, uint8_t *value)

Python: rp_I2C_SMBUS_Read(<reg>)
Reads 8 bit data from the specified register using
the SMBUS protocol.
<reg> - Register address in dec format.

1.04-18 and up
I2C:Smbus:Read<reg>:Word? > <value>
Example:
I2C:Smbus:Read2:Word? > 0
C++: rp_I2C_SMBUS_ReadWord(uint8_t reg, uint16_t *value)

Python: rp_I2C_SMBUS_ReadWord(<reg>)
Reads 16 bit data from the specified register using
the SMBUS protocol.
<reg> - Register address in dec format.

1.04-18 and up
- (NA)
C++: rp_I2C_SMBUS_ReadCommand(uint8_t *value)

Python: rp_I2C_SMBUS_ReadCommand()
Read command from I2C using the SMBUS protocol.

1.04-18 and up
I2C:Smbus:Read<reg>:Buffer<size>? >
<data>
Example:
I2C:Smbus:Read2:Buffer2? > {0,1}
C++: rp_I2C_SMBUS_ReadBuffer(uint8_t reg, uint8_t *buffer, int *len)

Python: rp_I2C_SMBUS_ReadBuffer(<reg>, <buffer>, <size>)
Reads buffer data from the specified register using
the SMBUS protocol.
<reg> - Register address in dec format.
<size> - Read data size.

1.04-18 and up
I2C:Smbus:Write<reg> <value>

Example:
I2C:Smbus:Write2 10
C++: rp_I2C_SMBUS_Write(uint8_t reg, uint8_t value)

Python: rp_I2C_SMBUS_Write(<reg>, <value>)
Writes 8-bit data to the specified register using
the SMBUS protocol.
<reg> - Register address in dec format.

1.04-18 and up
I2C:Smbus:Write<reg>:Word <value>

Example:
I2C:Smbus:Write2:Word 10
C++: rp_I2C_SMBUS_WriteWord(uint8_t reg, uint16_t value)

Python: rp_I2C_SMBUS_WriteWord(<reg>, <value>)
Writes 16-bit data to the specified register using
the SMBUS protocol.
<reg> - Register address in dec format.

1.04-18 and up
- (NA)
C++: rp_I2C_SMBUS_WriteCommand(uint8_t value)

Python: rp_I2C_SMBUS_WriteCommand(<value>)
Write command to I2C using the SMBUS protocol.

1.04-18 and up
I2C:Smbus:Write<reg>:Buffer<size> <data>

Example:
I2C:Smbus:Write2:Buffer2 0,1
C++: rp_I2C_SMBUS_WriteBuffer(uint8_t reg, uint8_t *buffer, int len)

Python: rp_I2C_SMBUS_WriteBuffer(<reg>, <buffer>, <len>)
Writes buffer data to the specified register using
the SMBUS protocol.
<reg> - Register address in dec format.
<size> - Read data size.

1.04-18 and up
I2C:IOctl:Read:Buffer<size>? > <data>
Example:
I2C:IOctl:Read:Buffer2? > {0,1}
C++: rp_I2C_IOCTL_ReadBuffer(uint8_t *buffer, int len)

Python: rp_I2C_IOCTL_ReadBuffer(<buffer>, <len>)
Reads data from the I2C device through IOCTL.
<size> - Read data size.

1.04-18 and up
I2C:IOctl:Write:Buffer<size> <data>
Example:
I2C:IOctl:Write:Buffer2  {0,1}
C++: rp_I2C_IOCTL_WriteBuffer(uint8_t *buffer, int len)

Python: rp_I2C_IOCTL_WriteBuffer(<buffer>, <len>)
Writes data to the I2C device via IOCTL.
<size> - Read data size.

1.04-18 and up
- (NA)
C++: N/A

Python: Buffer(<size>)

Creates a buffer for sending and receiving data.

2.04-35 and up

Note

SMBUS is a standardized protocol for communicating with I2C devices. Information about this protocol can be found in this link: SMBUS specifcations. IOCTL writes and reads data directly from I2C.