SPI Register Read

Read data from SPI peripheral device register

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Libraries:
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 peripheral 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

SDI — Data read from registers of an SPI peripheral device

vector

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

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

Parameters

Main

SPI module — SPI module to read data

0 (default)

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

Chip select pin — Pin connected to the SPI peripheral device

D7

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

First bit to transfer — First bit to transfer for SPI communication

Most significant bit (MSB) (default) | Least significant bit (LSB)

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.

Mode (Clock polarity and phase) — Mode of SPI communication

0 (default) | 1 | 2 | 3

An SPI controller 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.

Mode	Clock Polarity (CPOL)	Clock Phase (CPHA)
0	0	1
1	0	0
2	1	1
3	1	0

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

Register address — The SPI peripheral register address to read data

0 (default)

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

Output data type — Data type of data read from the SPI peripheral device

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

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

Output data length — Data size to read from the SPI peripheral device

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

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

Sample time — Frequency to read data from the SPI peripheral device

0.1 (default)

Specify how often the block reads data from the SPI peripheral 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

Chip select pin polarity — Logic level to establish SPI communication

Active low (default) | Active high

The logic levels supported by Chip select pin to select the SPI peripheral device.

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

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