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SPI Register Read

Read data from SPI slave device register

  • Library:
  • Simulink Coder Support Package for BBC micro:bit/Basic

    Simulink Coder Support Package for STMicroelectronics Nucleo Boards/ Common

    Simulink Coder Support Package for STMicroelectronics Discovery Boards/ STM32F746G-Discovery

    Simulink Coder Support Package for STMicroelectronics Discovery Boards/ STM32F769I-Discovery

Description

The SPI Register Read block reads the data from registers of a slave device over the Serial Peripheral Interface (SPI) interface. Using this block, you can access an SPI device to measure quantities such as temperature, pressure or to support EEPROM.

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

Ports

Output

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The port outputs the data read from the registers of a slave device over the SPI interface.

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

Parameters

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Main

Specify the SPI module to which the SPI slave device is connected.

Specify the pin number on the board to which the SPI slave device is connected. The SPI master pulls the SS pin of the selected slave to a low (0) value to start the communication. The slave is selected depending on the pin polarity that you specify in the Slave select pin polarity parameter. The master can select only one slave at a time.

Select the order in which the data is transmitted.

  • Most significant bit (MSB) — Select MSB to send the most significant bit (MSB) first.

  • Least significant bit (LSB) — Select LSB to send the least significant bit (LSB) first.

An SPI master sets the clock polarity (CPOL) and the clock phase (CPHA).

The combination of polarity and phase are referred to as SPI modes. The SPI modes 0–3 are shown in the table.

ModeClock Polarity (CPOL)Clock Phase (CPHA)
001
100
211
310

For more information on register read/write, see SPI Transfer Modes.

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

Specify the type of data read from the register of the SPI slave device.

Specify the length of data read from the register of the SPI slave device.

Specify how often the block reads data from the SPI slave device. When you specify this parameter as-1, Simulink® determines the best sample time for the block based on the block context within the model.

Advanced

The logic levels supported by Slave select pin to select the SPI slave device.

  • Active low — The device is enabled on logic low. The SPI slave device gets enabled when its SS pin is set to low.

  • Active high — The device is enabled on logic high. The SPI slave device gets enabled when its SS pin is set to high.