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UART Development Guide

ID: RK-KF-YF-053

Release Version: V1.0.0

Date: 2019-12-02

Security Level: Internal

DISCLAIMER

This document is provided "as is". Fuzhou Rockchip Electronics Co., Ltd. ("the Company", hereinafter the same) makes no express or implied representations or warranties regarding the accuracy, reliability, completeness, merchantability, fitness for a particular purpose, or non-infringement of any statements, information, and content in this document. This document is provided only as a reference for usage guidance.

Due to product version upgrades or other reasons, this document may be updated or modified periodically without any prior notice.

Trademark Statement

"Rockchip", "Rockchip", and "Rockchip" are all registered trademarks of the Company, owned by the Company.

All other registered trademarks or trademarks mentioned in this document are owned by their respective owners.

All rights reserved © 2019 Fuzhou Rockchip Electronics Co., Ltd.

Beyond the scope of reasonable use, no unit or individual may excerpt or copy any part or all of the content of this document without the written permission of the Company, and may not distribute it in any form.

Fuzhou Rockchip Electronics Co., Ltd.

Address: No. 18, Area A, Software Park, Tongpan Road, Fuzhou, Fujian Province

Website: www.rock-chips.com

Customer Service Tel: +86-4007-700-590

Customer Service Fax: +86-591-83951833

Customer Service Email: fae@rock-chips.com

Preface

Overview

Product Versions

Chip NameKernel Version
RK2206FreeRTOS V10.0.1

Intended Audience

This document (this guide) is mainly intended for the following engineers:

Technical Support Engineers Software Development Engineers

Revision History

VersionAuthorDateDescription
V1.0.0Liu Shifang2019-12-02Initial version

Table of Contents

[TOC]

Rockchip UART Features​

UART（Universal Asynchronous Receiver/Transmitter）

  • Compatible with 16550A.
  • UART0 has two iomux groups, UART1 has three iomux groups, and UART2 has two iomux groups.
  • Supports hardware automatic flow control (except UART1_M2).
  • Supports interrupt transfer mode and DMA transfer mode.
  • Supports up to 4M baud rate.

Software Development​

Code Path​

UART driver:

src/driver/uart/UartDevice.c // UART driver
include/driver/UartDevice.h
src/bsp/hal/lib/hal/src/hal_uart.c // UART hardware abstraction layer
src/bsp/hal/lib/hal/inc/hal_uart.h

UART test commands (user applications can refer to):

src/subsys/shell/shell_uart.c

UART Configuration​

In the board-level configuration iomux.c, you can view the iomux configuration of all UART devices. In the board-level configuration board.c, you can configure UART devices through the UartDevHwInit(uint32 DevID, uint32 Channel) function, and configure the UART Console device through the DebugInit(void) function.

In menuconfig, you can configure the uart devices to be used.

BSP Driver --->
    [*] Enable UART --->
        [*] Enable UART0
        [ ] Enable UART1
        [ ] Enable UART2

You can use the command shell command dev.list to view the generated UART devices.

UART Test​

Enable the UART test program:

Components Config --->
    Command shell --->
        [*] Enable Uart Shell

/* please openDMADevice driver */
BSP Driver --->
    Enable DMA --->
        [*] Enable DesignWare DMA Controlle

UART test commands:

/* send data */
uart_test w uart<value> baudrate [dma] [autoflow]
Example: uart_test w uart1 115200 1 0
/* receive data */
uart_test r uart<value> baudrate [dma] [autoflow]
Example: uart_test r uart1 115200 1 0

You can use the command shell command io to read and write UART device register values to check whether they meet expectations. For details about UART device registers, please refer to the datasheet.

Baud Rate Support​

Baud rates below 1.5M are all supported. Baud rates above 1.5M need to be tested to determine whether they are supported, because this is related to the CLK clock tree. The maximum baud rate that RK2206 can stably support is 4M.

Console Configuration​

In menuconfig, you can configure the uart device to be used as the console.

Target Options --->
    Board Options --->
        (0) DEBUG_UART