I2C Controller Read

Read data from I2C Peripheral devices or I2C Peripheral devices register

• 

Libraries:
Embedded Coder Support Package for STMicroelectronics Discovery Boards / STM32F769I-Discovery
Embedded Coder Support Package for STMicroelectronics Discovery Boards / STM32F746G-Discovery

Description

The I2C Controller Read block reads serial data from an I2C Peripheral devices that is connected to the board. Using this block, you can read data from a specific register on the I2C Peripheral devices.

For more information on I2C communication, see Support I2C Communication.

Ports

Output

Data — Data from the I2C Peripheral devices

vector

The port reads vector data from an I2C device on the board. The size of the data is the value that you specify in the Data size parameter.

Data Types: int8 | uint8 | int16 | uint16 | int32 | uint32 | single | double

Status — Status of the read operation

scalar

When you select the Output error status parameter, an output port, labeled as Status, becomes available.

The port outputs the status of each read request as mentioned in the following table:

Return status codes

Status	Description
0	SUCCESS
1	BUSY
2	ARBITRATION_LOST
4	NO_ACKNOWLEDGE
8	BUS_ERROR
16	BUS_NOT_IN_USE

Data Types: uint8

Parameters

I2C module — I2C module to read data

0 (default)

Specify the I2C module on the board to read data from the I2C Peripheral devices.

Peripheral address — The I2C register Peripheral address from which to read data

10 (default) | integer greater than or equal to 0

Specify the I2C Peripheral address to read the data. You can specify this address in hexadecimal format hex2dec(), for example, ‘hex2dec(‘20’)’.

Peripheral byte order — Byte ordering that your I2C Peripheral devices supports

BigEndian (default) | LittleEndian

The 2-byte ordering options are:

• BigEndian - The most significant byte is sent first over the I2C bus.

• LittleEndian - The least significant byte is sent first over the I2C bus.

Enable register access — Option to read from a specific I2C Peripheral register

on (default) | off

When you select this parameter, the block reads data from the I2C Peripheral register that you specify in the Peripheral register address parameter.

When you clear this parameter, the Send NACK at the end of data transfer and Remove stop bit at the end of data transfer parameters are displayed. Using these parameters, you can modify the read operation according to your requirements.

Peripheral register address — The I2C Peripheral register address to read data

0 (default) | integer between 0 and 255

Specify the I2C register address to read the data.

Specify this address as an integer or in hexadecimal format by using hex2dec(), for example, ‘hex2dec(‘20’)’.

For more information on register read/write, see I2C Register Read/Write.

Dependencies

This parameter appears only when you select Enable register access parameter.

Data type — Data type of data from the I2C Peripheral devices

uint8 (default) | int8 | int16 | uint16 | int32 | uint32 | single | double

Select the data type in which you want to read from the I2C Peripheral devices.

Data size (N) — Data size to read from the I2C Peripheral devices

1 (default) | integer greater than or equal to 0

Specify the data size that you want to read from the I2C Peripheral devices for the selected data type.

Send NACK at the end of data transfer — Option to send Not Acknowledge bit at the end of data transfer

off (default) | on

When you select this parameter, the I2C Controller Read block sends a NACK (Not Acknowledge) bit to the Peripheral devices with the final byte.

When the Peripheral devices receives the NACK, it waits for a STOP condition from the I2C Controller block. The Controller block generates either a STOP condition to abort the transfer or a repeated START condition to start a new transfer.

When you clear this parameter, the I2C Controller Read block sends an ACK (Acknowledge) bit to the Peripheral devices at the end of every byte. The ACK indicates that the I2C Controller Read block is ready to read the next byte from the Peripheral devices.

Dependencies

This parameter appears only when you clear Enable register access parameter.

Remove stop bit at the end of data transfer — Option to remove STOP bit at the end of data transfer

off (default) | on

When you clear this parameter, the block sends a STOP condition. This condition indicates that the block has terminated the data transmission and that the I2C bus is free for any other I2C Controller block to initiate the new read/write operation.

When you select this parameter, the block sends another START condition followed by an address and read/write bit. The block sends any number of start conditions recursively. Such a repeated START condition allows write operations to the Peripheral devices without releasing the bus. No other Controller block interrupts the operation.

Dependencies

This parameter appears only when you clear Enable register access parameter.

Output error status — Option to display the error status during data transmission

off (default) | on

When you select this parameter, an output port, labeled as Status, becomes available.

The port outputs 0 for a successful read operation.

Sample time — Frequency to read data from the I2C Peripheral devices

0.1 (default)

Specify how often the I2C Controller Read block reads data from the I2C Peripheral devices. When you specify this parameter as-1, the block inherits its sample time based on the context of the block within the model.

Version History

Introduced in R2018a