UART/USART Write

Write serial data from the Universal Asynchronous Receiver Transmitter (UART/USART) port

Since R2022a

Add-On Required: This feature requires the Embedded Coder Support Package for STMicroelectronics STM32 Processors add-on.

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Libraries:
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32F3xx Based Boards
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32F4xx Based Boards
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32F7xx Based Boards
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32G4xx Based Boards
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32H7xx Based Boards (Dual-core)
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32H7xx Based Boards (Single-core)
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32L4xx Based Boards
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32L5xx Based Boards
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32U5xx Based Boards
Embedded Coder Support Package for STMicroelectronics STM32 Processors / STM32WBxx Based Boards

Description

Write serial data from the Universal Asynchronous Receiver/ Transmitter (UART/USART) port.

The UART/USART Write block expects the data to be written as an [Nx1] or [1xN] array. Select Specify length of data to write to specify the length of input data to be written to the UART/USART port.

Ports

Input

Data — UART/USART write data

vector | scalar

The write data sent to the UART/USART port.

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

Length — UART/USART message length

scalar

The length of input data received at UART/USART port.

Dependencies

To enable this port, select the Specify length of input data to write parameter.

Data Types: uint8

Output

Status — Status of write operation

0 | 7 | 8

The status port outputs 0 i.e. no error in data reception or Success or any one of the bit values shown in the following table.

The table represents the bits and error associated with it.

Status

Bits	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Error	X	X	X	X	X	X	ARBE_ERROR	RX_BUSY	TX_BUSY	TX_FAILED	RX_BUFFER_FULL	NOISE_ERROR	FRAME_ERROR	PARITY_ERROR	OVERRUN ERROR	DATA_NOT_AVAILABLE

Port outputs status 7(transmit failed) and 8(transmit busy)which are valid only for UART/USART Write blocks.

• 0 — requested data length not received

• 1 — represents overrun error

• 2 — represents parity error

• 3 — represents frame error

• 4 — represents noise error

• 5 — represents receive buffer full

• 6 — represents transmit failed

• 7 — represents transmit busy

• 8 — represents receive busy

• 9 — represents auto baud rate error

Dependencies

To enable this port, select the Output status parameter.

Data Types: uint8

Parameters

UART/USART module — UART/USART module

USART1 (default) | USART2 | USART3 | UART4 | UART5 | USART6 | UART7 | UART8

Select the UART/USART module for the block.

Specify length of input data to write — Size of data to be read

off (default) | on

Select the Specify length of input data to write parameter to enable the port length.

Enable blocking mode — Enable blocking mode for data transmission

off (default) | on

• On - When you select this parameter, the write operation runs in the Blocking mode. If input data received in the previous time step is sent, the block accepts data from the input port. If the write operation is in progress, the block waits for the data to be sent, and then it accepts data from the input port.

  If the connection between the sending and the receiving host is not established, or if the connection is lost, the data at the input port is dropped.

  If previous byte transmit is already in progress, or the buffer is full (Buffered Mode), input data is not sent.

• Off - When you clear this parameter, the send operation runs in the Non-blocking mode. When sending data, if the transmission of the input data received in the previous time step is still in progress, the data at the input port at the given time step is dropped.

  If the connection between the sending and the receiving host is not established, or if the connection is lost, the data at the input port is dropped.

Blocking timeout (in s) — Time in seconds for blocking mode

0.1 (default) | non-negative value

Specify the time in seconds for blocking mode.

Dependencies

To enable this parameter, select the Enable blocking mode parameter.

Output status — Enable output status

off (default) | on

When you select the Output Status parameter, the block configures an output port, Status. The port outputs the status of UART/USART message.

More About

Buffered Mode

For UART/USART block, you can configure transmit mode using Buffered mode using TXE interrupt, Buffered mode using DMA and Polling mode in Configuration Parameters (Configuration Parameters > Hardware Implementation > Hardware Board > UART/USART > Transmit mode).

When you select Transmit mode as Buffered mode using TXE interrupt or Buffered mode using DMA, the data to be sent in every step is transmitted to an internal buffer. Later the data is transmitted to the transmit data register of the UART/USART from the buffer using DMA or interrupt as per the selected mode.

If previous data is not transmitted and buffer doesn't have enough space for the entire length of input data, you can either select one of the following options:

• Blocking mode enabled - the execution will wait till the specified timeout for the data from previous steps to be transmitted so that buffer has enough space. If the timeout expires and there is not enough space available in the buffer, the input data of that step will be discarded with TX_FAILED error bit set in status output. For more information on status, refer Output status.

• Blocking mode disabled - the input data of that step will be immediately discarded with TX_FAILED error bit set in status output

When you select Polling mode, the input data from every step is transmitted to the transmit data register of UART/USART byte by byte directly without any buffer.

If a byte of input data, cannot be transmitted to the transmit data register, you can either select one of the following options:

• Blocking mode enabled - the execution waits for the specified timeout period. If it is unable to write the byte to transmit data register even after the timeout, the remaining bytes of the input data are discarded with TX_FAILED error bit set in status output.

• Blocking mode disabled - the remaining bytes of the input data are immediately discarded with TX_FAILED error bit set in status output.

Note

It is recommended to enable blocking timeout if you are sending more than 1 byte using polling mode. To ensure every step we wait till the previous byte is transmitted from transmit data register to the UART bus and a new byte can be written to the transmit data register.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2022a