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Diff: TARGET_SAMD21G18A/TOOLCHAIN_ARM_STD/usart.h
- Revision:
- 171:3a7713b1edbc
- Parent:
- 111:4336505e4b1c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/TARGET_SAMD21G18A/TOOLCHAIN_ARM_STD/usart.h Thu Nov 08 11:45:42 2018 +0000 @@ -0,0 +1,1474 @@ +/** + * + * \file + * + * \brief SAM SERCOM USART Driver + * + * Copyright (C) 2012-2015 Atmel Corporation. All rights reserved. + * + * \asf_license_start + * + * \page License + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * + * 3. The name of Atmel may not be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * 4. This software may only be redistributed and used in connection with an + * Atmel microcontroller product. + * + * THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE + * EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR + * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + * \asf_license_stop + * + */ +/* + * Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a> + */ +#ifndef USART_H_INCLUDED +#define USART_H_INCLUDED + +/** + * \defgroup asfdoc_sam0_sercom_usart_group SAM Serial USART Driver (SERCOM USART) + * + * This driver for Atmel® | SMART SAM devices provides an interface for the configuration + * and management of the SERCOM module in its USART mode to transfer or receive + * USART data frames. The following driver API modes are covered by this + * manual: + * + * - Polled APIs + * \if USART_CALLBACK_MODE + * - Callback APIs + * \endif + * + * The following peripherals are used by this module: + * - SERCOM (Serial Communication Interface) + * + * The following devices can use this module: + * - Atmel | SMART SAM D20/D21 + * - Atmel | SMART SAM R21 + * - Atmel | SMART SAM D10/D11 + * - Atmel | SMART SAM L21 + * - Atmel | SMART SAM DAx + * - Atmel | SMART SAM C20/C21 + * + * The outline of this documentation is as follows: + * - \ref asfdoc_sam0_sercom_usart_prerequisites + * - \ref asfdoc_sam0_sercom_usart_overview + * - \ref asfdoc_sam0_sercom_usart_special_considerations + * - \ref asfdoc_sam0_sercom_usart_extra_info + * - \ref asfdoc_sam0_sercom_usart_examples + * - \ref asfdoc_sam0_sercom_usart_api_overview + * + * \section asfdoc_sam0_sercom_usart_prerequisites Prerequisites + * + * To use the USART you need to have a GCLK generator enabled and running + * that can be used as the SERCOM clock source. This can either be configured + * in conf_clocks.h or by using the system clock driver. + * + * \section asfdoc_sam0_sercom_usart_overview Module Overview + * + * This driver will use one (or more) SERCOM interfaces on the system + * and configure it to run as a USART interface in either synchronous + * or asynchronous mode. + * + * \subsection asfdoc_sam0_sercom_usart_features Driver Feature Macro Definition + * <table> + * <tr> + * <th>Driver Feature Macro</th> + * <th>Supported devices</th> + * </tr> + * <tr> + * <td>FEATURE_USART_SYNC_SCHEME_V2</td> + * <td>SAM D21/R21/D10/D11/L21/DAx/C20/C21</td> + * </tr> + * <tr> + * <td>FEATURE_USART_OVER_SAMPLE</td> + * <td>SAM D21/R21/D10/D11/L21/DAx/C20/C21</td> + * </tr> + * <tr> + * <td>FEATURE_USART_HARDWARE_FLOW_CONTROL</td> + * <td>SAM D21/R21/D10/D11/L21/DAx/C20/C21</td> + * </tr> + * <tr> + * <td>FEATURE_USART_IRDA</td> + * <td>SAM D21/R21/D10/D11/L21/DAx/C20/C21</td> + * </tr> + * <tr> + * <td>FEATURE_USART_LIN_SLAVE</td> + * <td>SAM D21/R21/D10/D11/L21/DAx/C20/C21</td> + * </tr> + * <tr> + * <td>FEATURE_USART_COLLISION_DECTION</td> + * <td>SAM D21/R21/D10/D11/L21/DAx/C20/C21</td> + * </tr> + * <tr> + * <td>FEATURE_USART_START_FRAME_DECTION</td> + * <td>SAM D21/R21/D10/D11/L21/DAx/C20/C21</td> + * </tr> + * <tr> + * <td>FEATURE_USART_IMMEDIATE_BUFFER_OVERFLOW_NOTIFICATION</td> + * <td>SAM D21/R21/D10/D11/L21/DAx/C20/C21</td> + * </tr> + * <tr> + * <td>FEATURE_USART_RS485</td> + * <td>SAM C20/C21</td> + * </tr> + * <tr> + * <td>FEATURE_USART_LIN_MASTER</td> + * <td>SAM C20/C21</td> + * </tr> + * </table> + * \note The specific features are only available in the driver when the + * selected device supports those features. + * + * \subsection asfdoc_sam0_sercom_usart_overview_frame_format Frame Format + * + * Communication is based on frames, where the frame format can be customized + * to accommodate a wide range of standards. A frame consists of a start bit, + * a number of data bits, an optional parity bit for error detection as well + * as a configurable length stop bit(s) - see + * \ref asfdoc_sam0_sercom_usart_frame_diagram "the figure below". + * \ref asfdoc_sam0_sercom_usart_frame_params "The table below" shows the + * available parameters you can change in a frame. + * + * \anchor asfdoc_sam0_sercom_usart_frame_params + * <table> + * <caption>USART Frame Parameters</caption> + * <tr> + * <th>Parameter</th> + * <th>Options</th> + * </tr> + * <tr> + * <td>Start bit</td> + * <td>1</td> + * </tr> + * <tr> + * <td>Data bits</td> + * <td>5, 6, 7, 8, 9</td> + * </tr> + * <tr> + * <td>Parity bit</td> + * <td>None, Even, Odd</td> + * </tr> + * <tr> + * <td>Stop bits</td> + * <td>1, 2</td> + * </tr> + * </table> + * + * \anchor asfdoc_sam0_sercom_usart_frame_diagram + * \image html usart_frame.svg "USART Frame Overview" width=100% + * + * \subsection asfdoc_sam0_sercom_usart_overview_sync Synchronous Mode + * + * In synchronous mode a dedicated clock line is provided; either by the USART + * itself if in master mode, or by an external master if in slave mode. + * Maximum transmission speed is the same as the GCLK clocking the USART + * peripheral when in slave mode, and the GCLK divided by two if in + * master mode. In synchronous mode the interface needs three lines to + * communicate: + * - TX (Transmit pin) + * - RX (Receive pin) + * - XCK (Clock pin) + * + * \subsubsection asfdoc_sam0_sercom_usart_overview_sync_sampling Data Sampling + * In synchronous mode the data is sampled on either the rising or falling edge + * of the clock signal. This is configured by setting the clock polarity in the + * configuration struct. + * + * \subsection asfdoc_sam0_sercom_usart_overview_async Asynchronous Mode + * + * In asynchronous mode no dedicated clock line is used, and the communication + * is based on matching the clock speed on the transmitter and receiver. The + * clock is generated from the internal SERCOM baudrate generator, and the + * frames are synchronized by using the frame start bits. Maximum transmission + * speed is limited to the SERCOM GCLK divided by 16. + * In asynchronous mode the interface only needs two lines to communicate: + * - TX (Transmit pin) + * - RX (Receive pin) + * + * \subsubsection asfdoc_sam0_sercom_usart_overview_async_clock_matching Transmitter/receiver Clock Matching + * + * For successful transmit and receive using the asynchronous mode the receiver + * and transmitter clocks needs to be closely matched. When receiving a frame + * that does not match the selected baudrate closely enough the receiver will + * be unable to synchronize the frame(s), and garbage transmissions will + * result. + * + * \subsection asfdoc_sam0_sercom_usart_parity Parity + * Parity can be enabled to detect if a transmission was in error. This is done + * by counting the number of "1" bits in the frame. When using Even parity the + * parity bit will be set if the total number of "1"s in the frame are an even + * number. If using Odd parity the parity bit will be set if the total number + * of "1"s are Odd. + * + * When receiving a character the receiver will count the number of "1"s in the + * frame and give an error if the received frame and parity bit disagree. + * + * \subsection asfdoc_sam0_sercom_usart_overview_pin_configuration GPIO Configuration + * + * The SERCOM module has four internal pads; the RX pin can be placed freely on + * any one of the four pads, and the TX and XCK pins have two predefined + * positions that can be selected as a pair. The pads can then be routed to an + * external GPIO pin using the normal pin multiplexing scheme on the SAM. + * + * \section asfdoc_sam0_sercom_usart_special_considerations Special Considerations + * + * \if USART_CALLBACK_MODE + * Never execute large portions of code in the callbacks. These + * are run from the interrupt routine, and thus having long callbacks will + * keep the processor in the interrupt handler for an equally long time. + * A common way to handle this is to use global flags signaling the + * main application that an interrupt event has happened, and only do the + * minimal needed processing in the callback. + * \else + * No special considerations. + * \endif + * + * \section asfdoc_sam0_sercom_usart_extra_info Extra Information + * + * For extra information, see \ref asfdoc_sam0_sercom_usart_extra. This includes: + * - \ref asfdoc_sam0_sercom_usart_extra_acronyms + * - \ref asfdoc_sam0_sercom_usart_extra_dependencies + * - \ref asfdoc_sam0_sercom_usart_extra_errata + * - \ref asfdoc_sam0_sercom_usart_extra_history + * + * \section asfdoc_sam0_sercom_usart_examples Examples + * + * For a list of examples related to this driver, see + * \ref asfdoc_sam0_sercom_usart_exqsg. + * + * \section asfdoc_sam0_sercom_usart_api_overview API Overview + * @{ + */ + +#include <compiler.h> +#include <sercom.h> +#include <pinmux.h> + +#if USART_CALLBACK_MODE == true +# include <sercom_interrupt.h> +#endif + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * \name Driver Feature Definition + * Define SERCOM USART features set according to different device family. + * @{ + */ +#if (SAMD21) || (SAMR21) || (SAMD10) || (SAMD11) || (SAML21) || \ + (SAMDA1) || (SAMC20) || (SAMC21) || defined(__DOXYGEN__) +/** Usart sync scheme version 2. */ +# define FEATURE_USART_SYNC_SCHEME_V2 +/** Usart over sampling. */ +# define FEATURE_USART_OVER_SAMPLE +/** Usart hardware control flow. */ +# define FEATURE_USART_HARDWARE_FLOW_CONTROL +/** IrDA mode. */ +# define FEATURE_USART_IRDA +/** LIN slave mode. */ +# define FEATURE_USART_LIN_SLAVE +/** Usart collision detection. */ +# define FEATURE_USART_COLLISION_DECTION +/** Usart start frame detection. */ +# define FEATURE_USART_START_FRAME_DECTION +/** Usart start buffer overflow notification. */ +# define FEATURE_USART_IMMEDIATE_BUFFER_OVERFLOW_NOTIFICATION +#endif + +#if (SAMC20) || (SAMC21) || defined(__DOXYGEN__) +/** LIN master mode. */ +#define FEATURE_USART_LIN_MASTER +/** RS485 mode. */ +# define FEATURE_USART_RS485 +#endif +/*@}*/ + +#ifdef FEATURE_USART_LIN_MASTER +/** + * \brief LIN Node Type. + * + * LIN node type. + */ +enum lin_node_type { + /** LIN master mode */ + LIN_MASTER_NODE = SERCOM_USART_CTRLA_FORM(0x02), + /** LIN slave mode */ + LIN_SLAVE_NODE = SERCOM_USART_CTRLA_FORM(0x04), + /** Neither LIN master nor LIN slave mode */ + LIN_INVALID_MODE = SERCOM_USART_CTRLA_FORM(0x00), +}; + +/** + * \brief LIN Master Command Enum. + * + * LIN master command enum. + */ +enum lin_master_cmd { + /** LIN master software control transmission command */ + LIN_MASTER_SOFTWARE_CONTROL_TRANSMIT_CMD = SERCOM_USART_CTRLB_LINCMD(0x01), + /** LIN master automatically transmission command */ + LIN_MASTER_AUTO_TRANSMIT_CMD = SERCOM_USART_CTRLB_LINCMD(0x02), +}; + +/** + * \brief LIN Master Header Delay. + * + * LIN master header delay between break and sync transmission, + * and between the sync and identifier (ID) fields. + * This field is only valid when using automatically transmission command + */ +enum lin_master_header_delay { + /** Delay between break and sync transmission is 1 bit time. + Delay between sync and ID transmission is 1 bit time. */ + LIN_MASTER_HEADER_DELAY_0 = SERCOM_USART_CTRLC_HDRDLY(0x0), + /** Delay between break and sync transmission is 4 bit time. + Delay between sync and ID transmission is 4 bit time. */ + LIN_MASTER_HEADER_DELAY_1 = SERCOM_USART_CTRLC_HDRDLY(0x01), + /** Delay between break and sync transmission is 8 bit time. + Delay between sync and ID transmission is 4 bit time. */ + LIN_MASTER_HEADER_DELAY_2 = SERCOM_USART_CTRLC_HDRDLY(0x02), + /** Delay between break and sync transmission is 14 bit time. + Delay between sync and ID transmission is 4 bit time. */ + LIN_MASTER_HEADER_DELAY_3 = SERCOM_USART_CTRLC_HDRDLY(0x03), +}; + +/** + * \brief LIN Master Break Length. + * + * Length of the break field transmitted when in LIN master mode + */ +enum lin_master_break_length { + /** Break field transmission is 13 bit times. */ + LIN_MASTER_BREAK_LENGTH_13_BIT = SERCOM_USART_CTRLC_BRKLEN(0x0), + /** Break field transmission is 17 bit times. */ + LIN_MASTER_BREAK_LENGTH_17_BIT = SERCOM_USART_CTRLC_BRKLEN(0x1), + /** Break field transmission is 21 bit times. */ + LIN_MASTER_BREAK_LENGTH_21_BIT = SERCOM_USART_CTRLC_BRKLEN(0x2), + /** Break field transmission is 26 bit times. */ + LIN_MASTER_BREAK_LENGTH_26_BIT = SERCOM_USART_CTRLC_BRKLEN(0x3), +}; +#endif + +#ifndef PINMUX_DEFAULT +/** Default pinmux. */ +# define PINMUX_DEFAULT 0 +#endif + +#ifndef PINMUX_UNUSED +/** Unused pinmux. */ +# define PINMUX_UNUSED 0xFFFFFFFF +#endif + +#ifndef USART_TIMEOUT +/** USART timeout value. */ +# define USART_TIMEOUT 0xFFFF +#endif + +#if USART_CALLBACK_MODE == true +/** + * \brief USART Callback enum + * + * Callbacks for the Asynchronous USART driver. + */ +enum usart_callback { + /** Callback for buffer transmitted. */ + USART_CALLBACK_BUFFER_TRANSMITTED, + /** Callback for buffer received. */ + USART_CALLBACK_BUFFER_RECEIVED, + /** Callback for error. */ + USART_CALLBACK_ERROR, +#ifdef FEATURE_USART_LIN_SLAVE + /** Callback for break character is received. */ + USART_CALLBACK_BREAK_RECEIVED, +#endif +#ifdef FEATURE_USART_HARDWARE_FLOW_CONTROL + /** Callback for a change is detected on the CTS pin. */ + USART_CALLBACK_CTS_INPUT_CHANGE, +#endif +#ifdef FEATURE_USART_START_FRAME_DECTION + /** Callback for a start condition is detected on the RxD line. */ + USART_CALLBACK_START_RECEIVED, +#endif +# if !defined(__DOXYGEN__) + /** Number of available callbacks. */ + USART_CALLBACK_N, +# endif +}; +#endif + +/** + * \brief USART Data Order enum + * + * The data order decides which of MSB or LSB is shifted out first when data is + * transferred. + */ +enum usart_dataorder { + /** The MSB will be shifted out first during transmission, + * and shifted in first during reception. */ + USART_DATAORDER_MSB = 0, + /** The LSB will be shifted out first during transmission, + * and shifted in first during reception. */ + USART_DATAORDER_LSB = SERCOM_USART_CTRLA_DORD, +}; + +/** + * \brief USART Transfer mode enum + * + * Select USART transfer mode. + */ +enum usart_transfer_mode { + /** Transfer of data is done synchronously. */ + USART_TRANSFER_SYNCHRONOUSLY = (SERCOM_USART_CTRLA_CMODE), + /** Transfer of data is done asynchronously. */ + USART_TRANSFER_ASYNCHRONOUSLY = 0 +}; + +/** + * \brief USART Parity enum + * + * Select parity USART parity mode. + */ +enum usart_parity { + /** For odd parity checking, the parity bit will be set if number of + * ones being transferred is even. */ + USART_PARITY_ODD = SERCOM_USART_CTRLB_PMODE, + + /** For even parity checking, the parity bit will be set if number of + * ones being received is odd. */ + USART_PARITY_EVEN = 0, + + /** No parity checking will be executed, and there will be no parity bit + * in the received frame. */ + USART_PARITY_NONE = 0xFF, +}; + +/** + * \brief USART signal MUX settings + * + * Set the functionality of the SERCOM pins. + * + * See \ref asfdoc_sam0_sercom_usart_mux_settings for a description of the + * various MUX setting options. + */ +enum usart_signal_mux_settings { +#ifdef FEATURE_USART_HARDWARE_FLOW_CONTROL + /** MUX setting RX_0_TX_0_XCK_1. */ + USART_RX_0_TX_0_XCK_1 = (SERCOM_USART_CTRLA_RXPO(0) | SERCOM_USART_CTRLA_TXPO(0)), + /** MUX setting RX_0_TX_2_XCK_3. */ + USART_RX_0_TX_2_XCK_3 = (SERCOM_USART_CTRLA_RXPO(0) | SERCOM_USART_CTRLA_TXPO(1)), + /** MUX setting USART_RX_0_TX_0_RTS_2_CTS_3. */ + USART_RX_0_TX_0_RTS_2_CTS_3 = (SERCOM_USART_CTRLA_RXPO(0) | SERCOM_USART_CTRLA_TXPO(2)), + /** MUX setting RX_1_TX_0_XCK_1. */ + USART_RX_1_TX_0_XCK_1 = (SERCOM_USART_CTRLA_RXPO(1) | SERCOM_USART_CTRLA_TXPO(0)), + /** MUX setting RX_1_TX_2_XCK_3. */ + USART_RX_1_TX_2_XCK_3 = (SERCOM_USART_CTRLA_RXPO(1) | SERCOM_USART_CTRLA_TXPO(1)), + /** MUX setting USART_RX_1_TX_0_RTS_2_CTS_3. */ + USART_RX_1_TX_0_RTS_2_CTS_3 = (SERCOM_USART_CTRLA_RXPO(1) | SERCOM_USART_CTRLA_TXPO(2)), + /** MUX setting RX_2_TX_0_XCK_1. */ + USART_RX_2_TX_0_XCK_1 = (SERCOM_USART_CTRLA_RXPO(2) | SERCOM_USART_CTRLA_TXPO(0)), + /** MUX setting RX_2_TX_2_XCK_3. */ + USART_RX_2_TX_2_XCK_3 = (SERCOM_USART_CTRLA_RXPO(2) | SERCOM_USART_CTRLA_TXPO(1)), + /** MUX setting USART_RX_2_TX_0_RTS_2_CTS_3. */ + USART_RX_2_TX_0_RTS_2_CTS_3 = (SERCOM_USART_CTRLA_RXPO(2) | SERCOM_USART_CTRLA_TXPO(2)), + /** MUX setting RX_3_TX_0_XCK_1. */ + USART_RX_3_TX_0_XCK_1 = (SERCOM_USART_CTRLA_RXPO(3) | SERCOM_USART_CTRLA_TXPO(0)), + /** MUX setting RX_3_TX_2_XCK_3. */ + USART_RX_3_TX_2_XCK_3 = (SERCOM_USART_CTRLA_RXPO(3) | SERCOM_USART_CTRLA_TXPO(1)), + /** MUX setting USART_RX_3_TX_0_RTS_2_CTS_3. */ + USART_RX_3_TX_0_RTS_2_CTS_3 = (SERCOM_USART_CTRLA_RXPO(3) | SERCOM_USART_CTRLA_TXPO(2)), +#ifdef FEATURE_USART_RS485 + /** MUX setting USART_RX_0_TX_0_XCK_1_TE_2. */ + USART_RX_0_TX_0_XCK_1_TE_2 = (SERCOM_USART_CTRLA_RXPO(0) | SERCOM_USART_CTRLA_TXPO(3)), + /** MUX setting USART_RX_1_TX_0_XCK_1_TE_2. */ + USART_RX_1_TX_0_XCK_1_TE_2 = (SERCOM_USART_CTRLA_RXPO(1) | SERCOM_USART_CTRLA_TXPO(3)), + /** MUX setting USART_RX_2_TX_0_XCK_1_TE_2. */ + USART_RX_2_TX_0_XCK_1_TE_2 = (SERCOM_USART_CTRLA_RXPO(2) | SERCOM_USART_CTRLA_TXPO(3)), + /** MUX setting USART_RX_3_TX_0_XCK_1_TE_2. */ + USART_RX_3_TX_0_XCK_1_TE_2 = (SERCOM_USART_CTRLA_RXPO(3) | SERCOM_USART_CTRLA_TXPO(3)), +#endif +#else + /** MUX setting RX_0_TX_0_XCK_1. */ + USART_RX_0_TX_0_XCK_1 = (SERCOM_USART_CTRLA_RXPO(0)), + /** MUX setting RX_0_TX_2_XCK_3. */ + USART_RX_0_TX_2_XCK_3 = (SERCOM_USART_CTRLA_RXPO(0) | SERCOM_USART_CTRLA_TXPO), + /** MUX setting RX_1_TX_0_XCK_1. */ + USART_RX_1_TX_0_XCK_1 = (SERCOM_USART_CTRLA_RXPO(1)), + /** MUX setting RX_1_TX_2_XCK_3. */ + USART_RX_1_TX_2_XCK_3 = (SERCOM_USART_CTRLA_RXPO(1) | SERCOM_USART_CTRLA_TXPO), + /** MUX setting RX_2_TX_0_XCK_1. */ + USART_RX_2_TX_0_XCK_1 = (SERCOM_USART_CTRLA_RXPO(2)), + /** MUX setting RX_2_TX_2_XCK_3. */ + USART_RX_2_TX_2_XCK_3 = (SERCOM_USART_CTRLA_RXPO(2) | SERCOM_USART_CTRLA_TXPO), + /** MUX setting RX_3_TX_0_XCK_1. */ + USART_RX_3_TX_0_XCK_1 = (SERCOM_USART_CTRLA_RXPO(3)), + /** MUX setting RX_3_TX_2_XCK_3. */ + USART_RX_3_TX_2_XCK_3 = (SERCOM_USART_CTRLA_RXPO(3) | SERCOM_USART_CTRLA_TXPO), +#endif +}; + +/** + * \brief USART Stop Bits enum + * + * Number of stop bits for a frame. + */ +enum usart_stopbits { + /** Each transferred frame contains one stop bit. */ + USART_STOPBITS_1 = 0, + /** Each transferred frame contains two stop bits. */ + USART_STOPBITS_2 = SERCOM_USART_CTRLB_SBMODE, +}; + +/** + * \brief USART Character Size + * + * Number of bits for the character sent in a frame. + */ +enum usart_character_size { + /** The char being sent in a frame is five bits long. */ + USART_CHARACTER_SIZE_5BIT = SERCOM_USART_CTRLB_CHSIZE(5), + /** The char being sent in a frame is six bits long. */ + USART_CHARACTER_SIZE_6BIT = SERCOM_USART_CTRLB_CHSIZE(6), + /** The char being sent in a frame is seven bits long. */ + USART_CHARACTER_SIZE_7BIT = SERCOM_USART_CTRLB_CHSIZE(7), + /** The char being sent in a frame is eight bits long. */ + USART_CHARACTER_SIZE_8BIT = SERCOM_USART_CTRLB_CHSIZE(0), + /** The char being sent in a frame is nine bits long. */ + USART_CHARACTER_SIZE_9BIT = SERCOM_USART_CTRLB_CHSIZE(1), +}; + +#ifdef FEATURE_USART_OVER_SAMPLE +/** + * \brief USART Sample Rate + * + * The value of sample rate and baudrate generation mode. + */ +enum usart_sample_rate { + /** 16x over-sampling using arithmetic baudrate generation. */ + USART_SAMPLE_RATE_16X_ARITHMETIC = SERCOM_USART_CTRLA_SAMPR(0), + /** 16x over-sampling using fractional baudrate generation. */ + USART_SAMPLE_RATE_16X_FRACTIONAL = SERCOM_USART_CTRLA_SAMPR(1), + /** 8x over-sampling using arithmetic baudrate generation. */ + USART_SAMPLE_RATE_8X_ARITHMETIC = SERCOM_USART_CTRLA_SAMPR(2), + /** 8x over-sampling using fractional baudrate generation. */ + USART_SAMPLE_RATE_8X_FRACTIONAL = SERCOM_USART_CTRLA_SAMPR(3), + /** 3x over-sampling using arithmetic baudrate generation. */ + USART_SAMPLE_RATE_3X_ARITHMETIC = SERCOM_USART_CTRLA_SAMPR(4), +}; + +/** + * \brief USART Sample Adjustment + * + * The value of sample number used for majority voting. + */ +enum usart_sample_adjustment { + /** The first, middle and last sample number used for majority voting is 7-8-9. */ + USART_SAMPLE_ADJUSTMENT_7_8_9 = SERCOM_USART_CTRLA_SAMPA(0), + /** The first, middle and last sample number used for majority voting is 9-10-11. */ + USART_SAMPLE_ADJUSTMENT_9_10_11 = SERCOM_USART_CTRLA_SAMPA(1), + /** The first, middle and last sample number used for majority voting is 11-12-13. */ + USART_SAMPLE_ADJUSTMENT_11_12_13 = SERCOM_USART_CTRLA_SAMPA(2), + /** The first, middle and last sample number used for majority voting is 13-14-15. */ + USART_SAMPLE_ADJUSTMENT_13_14_15 = SERCOM_USART_CTRLA_SAMPA(3), +}; +#endif + +#ifdef FEATURE_USART_RS485 +/** + * \brief RS485 Guard Time + * + * The value of RS485 guard time. + */ +enum rs485_guard_time { + /** The guard time is 0-bit time. */ + RS485_GUARD_TIME_0_BIT = 0, + /** The guard time is 1-bit time. */ + RS485_GUARD_TIME_1_BIT, + /** The guard time is 2-bit times. */ + RS485_GUARD_TIME_2_BIT, + /** The guard time is 3-bit times. */ + RS485_GUARD_TIME_3_BIT, + /** The guard time is 4-bit times. */ + RS485_GUARD_TIME_4_BIT, + /** The guard time is 5-bit times. */ + RS485_GUARD_TIME_5_BIT, + /** The guard time is 6-bit times. */ + RS485_GUARD_TIME_6_BIT, + /** The guard time is 7-bit times. */ + RS485_GUARD_TIME_7_BIT, +}; +#endif + +/** + * \brief USART Transceiver + * + * Select Receiver or Transmitter. + */ +enum usart_transceiver_type { + /** The parameter is for the Receiver. */ + USART_TRANSCEIVER_RX, + /** The parameter is for the Transmitter. */ + USART_TRANSCEIVER_TX, +}; + +/** + * \brief USART configuration struct + * + * Configuration options for USART. + */ +struct usart_config { + /** USART bit order (MSB or LSB first). */ + enum usart_dataorder data_order; + /** USART in asynchronous or synchronous mode. */ + enum usart_transfer_mode transfer_mode; + /** USART parity. */ + enum usart_parity parity; + /** Number of stop bits. */ + enum usart_stopbits stopbits; + /** USART character size. */ + enum usart_character_size character_size; + /** USART pin out. */ + enum usart_signal_mux_settings mux_setting; +#ifdef FEATURE_USART_OVER_SAMPLE + /** USART sample rate. */ + enum usart_sample_rate sample_rate; + /** USART sample adjustment. */ + enum usart_sample_adjustment sample_adjustment; +#endif +#ifdef FEATURE_USART_IMMEDIATE_BUFFER_OVERFLOW_NOTIFICATION + /** Controls when the buffer overflow status bit is asserted when a buffer overflow occurs.*/ + bool immediate_buffer_overflow_notification; +#endif +#ifdef FEATURE_USART_IRDA + /** Enable IrDA encoding format. */ + bool encoding_format_enable; + /** The minimum pulse length that is required for a pulse to be accepted by the IrDA receiver. */ + uint8_t receive_pulse_length; +#endif +#ifdef FEATURE_USART_LIN_SLAVE + /** Enable LIN Slave Support. */ + bool lin_slave_enable; +#endif + +#ifdef FEATURE_USART_LIN_MASTER + /** LIN node type. */ + enum lin_node_type lin_node; + /** LIN master header delay. */ + enum lin_master_header_delay lin_header_delay; + /** LIN Master Break Length. */ + enum lin_master_break_length lin_break_length; +#endif + +#ifdef FEATURE_USART_START_FRAME_DECTION + /** Enable start of frame dection. */ + bool start_frame_detection_enable; +#endif +#ifdef FEATURE_USART_RS485 + /** RS485 guard time. */ + enum rs485_guard_time rs485_guard_time; +#endif +#ifdef FEATURE_USART_COLLISION_DECTION + /** Enable collision dection. */ + bool collision_detection_enable; +#endif + /** USART baudrate. */ + uint32_t baudrate; + /** Enable receiver. */ + bool receiver_enable; + /** Enable transmitter. */ + bool transmitter_enable; + + /** USART Clock Polarity. + * If true, data changes on falling XCK edge and + * is sampled at rising edge. + * If false, data changes on rising XCK edge and + * is sampled at falling edge. + * */ + bool clock_polarity_inverted; + + /** States whether to use the external clock applied to the XCK pin. + * In synchronous mode the shift register will act directly on the XCK clock. + * In asynchronous mode the XCK will be the input to the USART hardware module. + */ + bool use_external_clock; + /** External clock frequency in synchronous mode. + * This must be set if \c use_external_clock is true. */ + uint32_t ext_clock_freq; + /** If true the USART will be kept running in Standby sleep mode. */ + bool run_in_standby; + /** GCLK generator source. */ + enum gclk_generator generator_source; + /** PAD0 pinmux. + * + * If current USARTx has several alternative multiplexing I/O pin for PAD0, then + * only one peripheral multiplexing I/O can be enabled for current USARTx PAD0 + * function. Make sure other alternative multiplexing I/O associated current + * USARTx PAD0 is not setup usart function. + */ + uint32_t pinmux_pad0; + /** PAD1 pinmux. + * + * If current USARTx has several alternative multiplexing I/O pin for PAD1, then + * only one peripheral multiplexing I/O can be enabled for current USARTx PAD1 + * function. Make sure other alternative multiplexing I/O associated current + * USARTx PAD1 is not setup usart function. + */ + uint32_t pinmux_pad1; + /** PAD2 pinmux. + * + * If current USARTx has several alternative multiplexing I/O pin for PAD2, then + * only one peripheral multiplexing I/O can be enabled for current USARTx PAD2 + * function. Make sure other alternative multiplexing I/O associated current + * USARTx PAD2 is not setup usart function. + */ + uint32_t pinmux_pad2; + /** PAD3 pinmux. + * + * If current USARTx has several alternative multiplexing I/O pin for PAD3, then + * only one peripheral multiplexing I/O can be enabled for current USARTx PAD3 + * function. Make sure other alternative multiplexing I/O associated current + * USARTx PAD3 is not setup usart function. + */ + uint32_t pinmux_pad3; +}; + +#if USART_CALLBACK_MODE == true +/** + * \brief USART module instance + * + * Forward Declaration for the device instance. + */ +struct usart_module; + +/** + * \brief USART callback type + * + * Type of the callback functions. + */ +typedef void (*usart_callback_t)(struct usart_module *const module); +#endif + +/** + * \brief SERCOM USART driver software device instance structure. + * + * SERCOM USART driver software instance structure, used to retain software + * state information of an associated hardware module instance. + * + * \note The fields of this structure should not be altered by the user + * application; they are reserved for module-internal use only. + */ +struct usart_module { +#if !defined(__DOXYGEN__) + /** Pointer to the hardware instance. */ + Sercom *hw; + /** Module lock. */ + volatile bool locked; + /** Character size of the data being transferred. */ + enum usart_character_size character_size; + /** Receiver enabled. */ + bool receiver_enabled; + /** Transmitter enabled. */ + bool transmitter_enabled; +#ifdef FEATURE_USART_LIN_SLAVE + /** LIN Slave Support enabled. */ + bool lin_slave_enabled; +#endif +#ifdef FEATURE_USART_START_FRAME_DECTION + /** Start of frame dection enabled. */ + bool start_frame_detection_enabled; +#endif +# if USART_CALLBACK_MODE == true + /** Array to store callback function pointers in. */ + usart_callback_t callback[USART_CALLBACK_N]; + /** Buffer pointer to where the next received character will be put. */ + volatile uint8_t *rx_buffer_ptr; + + /** Buffer pointer to where the next character will be transmitted from. + **/ + volatile uint8_t *tx_buffer_ptr; + /** Remaining characters to receive. */ + volatile uint16_t remaining_rx_buffer_length; + /** Remaining characters to transmit. */ + volatile uint16_t remaining_tx_buffer_length; + /** Bit mask for callbacks registered. */ + uint8_t callback_reg_mask; + /** Bit mask for callbacks enabled. */ + uint8_t callback_enable_mask; + /** Holds the status of the ongoing or last read operation. */ + volatile enum status_code rx_status; + /** Holds the status of the ongoing or last write operation. */ + volatile enum status_code tx_status; +# endif +#endif +}; + +/** +* \name Lock/Unlock +* @{ +*/ + +/** + * \brief Attempt to get lock on driver instance + * + * This function checks the instance's lock, which indicates whether or not it + * is currently in use, and sets the lock if it was not already set. + * + * The purpose of this is to enable exclusive access to driver instances, so + * that, e.g., transactions by different services will not interfere with each + * other. + * + * \param[in,out] module Pointer to the driver instance to lock + * + * \retval STATUS_OK If the module was locked + * \retval STATUS_BUSY If the module was already locked + */ +static inline enum status_code usart_lock( + struct usart_module *const module) +{ + enum status_code status; + + system_interrupt_enter_critical_section(); + + if (module->locked) { + status = STATUS_BUSY; + } else { + module->locked = true; + status = STATUS_OK; + } + + system_interrupt_leave_critical_section(); + + return status; +} + +/** + * \brief Unlock driver instance + * + * This function clears the instance lock, indicating that it is available for + * use. + * + * \param[in,out] module Pointer to the driver instance to lock + * + */ +static inline void usart_unlock(struct usart_module *const module) +{ + module->locked = false; +} + +/** @} */ + +/** + * \brief Check if peripheral is busy syncing registers across clock domains + * + * Return peripheral synchronization status. If doing a non-blocking + * implementation this function can be used to check the sync state and hold of + * any new actions until sync is complete. If this functions is not run; the + * functions will block until the sync has completed. + * + * \param[in] module Pointer to peripheral module + * + * \return Peripheral sync status. + * + * \retval true Peripheral is busy syncing + * \retval false Peripheral is not busy syncing and can be read/written without + * stalling the bus. + */ +static inline bool usart_is_syncing( + const struct usart_module *const module) +{ + /* Sanity check arguments */ + Assert(module); + Assert(module->hw); + + SercomUsart *const usart_hw = &(module->hw->USART); + +#ifdef FEATURE_USART_SYNC_SCHEME_V2 + return (usart_hw->SYNCBUSY.reg); +#else + return (usart_hw->STATUS.reg & SERCOM_USART_STATUS_SYNCBUSY); +#endif +} + +#if !defined (__DOXYGEN__) +/** + * \internal + * Waits until synchronization is complete + */ +static inline void _usart_wait_for_sync( + const struct usart_module *const module) +{ + /* Sanity check. */ + Assert(module); + + while (usart_is_syncing(module)) { + /* Wait until the synchronization is complete */ + } +} +#endif + +/** + * \brief Initializes the device to predefined defaults + * + * Initialize the USART device to predefined defaults: + * - 8-bit asynchronous USART + * - No parity + * - One stop bit + * - 9600 baud + * - Transmitter enabled + * - Receiver enabled + * - GCLK generator 0 as clock source + * - Default pin configuration + * + * The configuration struct will be updated with the default + * configuration. + * + * \param[in,out] config Pointer to configuration struct + */ +static inline void usart_get_config_defaults( + struct usart_config *const config) +{ + /* Sanity check arguments */ + Assert(config); + + /* Set default config in the config struct */ + config->data_order = USART_DATAORDER_LSB; + config->transfer_mode = USART_TRANSFER_ASYNCHRONOUSLY; + config->parity = USART_PARITY_NONE; + config->stopbits = USART_STOPBITS_1; + config->character_size = USART_CHARACTER_SIZE_8BIT; + config->baudrate = 9600; + config->receiver_enable = true; + config->transmitter_enable = true; + config->clock_polarity_inverted = false; + config->use_external_clock = false; + config->ext_clock_freq = 0; + config->mux_setting = USART_RX_1_TX_2_XCK_3; + config->run_in_standby = false; + config->generator_source = GCLK_GENERATOR_0; + config->pinmux_pad0 = PINMUX_DEFAULT; + config->pinmux_pad1 = PINMUX_DEFAULT; + config->pinmux_pad2 = PINMUX_DEFAULT; + config->pinmux_pad3 = PINMUX_DEFAULT; +#ifdef FEATURE_USART_OVER_SAMPLE + config->sample_adjustment = USART_SAMPLE_ADJUSTMENT_7_8_9; + config->sample_rate = USART_SAMPLE_RATE_16X_ARITHMETIC; +#endif +#ifdef FEATURE_USART_LIN_SLAVE + config->lin_slave_enable = false; +#endif + +#ifdef FEATURE_USART_LIN_MASTER + config->lin_node = LIN_INVALID_MODE; + config->lin_header_delay = LIN_MASTER_HEADER_DELAY_0; + config->lin_break_length = LIN_MASTER_BREAK_LENGTH_13_BIT; +#endif + +#ifdef FEATURE_USART_IMMEDIATE_BUFFER_OVERFLOW_NOTIFICATION + config->immediate_buffer_overflow_notification = false; +#endif +#ifdef FEATURE_USART_START_FRAME_DECTION + config->start_frame_detection_enable = false; +#endif +#ifdef FEATURE_USART_IRDA + config->encoding_format_enable = false; + config->receive_pulse_length = 19; +#endif +#ifdef FEATURE_USART_COLLISION_DECTION + config->collision_detection_enable = false; +#endif +#ifdef FEATURE_USART_RS485 + config->rs485_guard_time = RS485_GUARD_TIME_0_BIT; +#endif +} + +enum status_code usart_init( + struct usart_module *const module, + Sercom *const hw, + const struct usart_config *const config); + +/** + * \brief Enable the module + * + * Enables the USART module. + * + * \param[in] module Pointer to USART software instance struct + */ +static inline void usart_enable( + const struct usart_module *const module) +{ + /* Sanity check arguments */ + Assert(module); + Assert(module->hw); + + /* Get a pointer to the hardware module instance */ + SercomUsart *const usart_hw = &(module->hw->USART); + +#if USART_CALLBACK_MODE == true + /* Enable Global interrupt for module */ + system_interrupt_enable(_sercom_get_interrupt_vector(module->hw)); +#endif + + /* Wait until synchronization is complete */ + _usart_wait_for_sync(module); + + /* Enable USART module */ + usart_hw->CTRLA.reg |= SERCOM_USART_CTRLA_ENABLE; +} + +/** + * \brief Disable module + * + * Disables the USART module. + * + * \param[in] module Pointer to USART software instance struct + */ +static inline void usart_disable( + const struct usart_module *const module) +{ + /* Sanity check arguments */ + Assert(module); + Assert(module->hw); + + /* Get a pointer to the hardware module instance */ + SercomUsart *const usart_hw = &(module->hw->USART); + +#if USART_CALLBACK_MODE == true + /* Disable Global interrupt for module */ + system_interrupt_disable(_sercom_get_interrupt_vector(module->hw)); +#endif + /* Wait until synchronization is complete */ + _usart_wait_for_sync(module); + + /* Disable USART module */ + usart_hw->CTRLA.reg &= ~SERCOM_USART_CTRLA_ENABLE; +} + +/** + * \brief Resets the USART module + * + * Disables and resets the USART module. + * + * \param[in] module Pointer to the USART software instance struct + */ +static inline void usart_reset( + const struct usart_module *const module) +{ + /* Sanity check arguments */ + Assert(module); + Assert(module->hw); + + /* Get a pointer to the hardware module instance */ + SercomUsart *const usart_hw = &(module->hw->USART); + + usart_disable(module); + + /* Wait until synchronization is complete */ + _usart_wait_for_sync(module); + + /* Reset module */ + usart_hw->CTRLA.reg = SERCOM_USART_CTRLA_SWRST; +} + +/** + * \name Writing and Reading + * @{ + */ +enum status_code usart_write_wait( + struct usart_module *const module, + const uint16_t tx_data); + +enum status_code usart_read_wait( + struct usart_module *const module, + uint16_t *const rx_data); + +enum status_code usart_write_buffer_wait( + struct usart_module *const module, + const uint8_t *tx_data, + uint16_t length); + +enum status_code usart_read_buffer_wait( + struct usart_module *const module, + uint8_t *rx_data, + uint16_t length); +/** @} */ + +/** + * \name Enabling/Disabling Receiver and Transmitter + * @{ + */ + +/** + * \brief Enable Transceiver + * + * Enable the given transceiver. Either RX or TX. + * + * \param[in] module Pointer to USART software instance struct + * \param[in] transceiver_type Transceiver type + */ +static inline void usart_enable_transceiver( + struct usart_module *const module, + enum usart_transceiver_type transceiver_type) +{ + /* Sanity check arguments */ + Assert(module); + Assert(module->hw); + + /* Get a pointer to the hardware module instance */ + SercomUsart *const usart_hw = &(module->hw->USART); + + /* Wait until synchronization is complete */ + _usart_wait_for_sync(module); + + switch (transceiver_type) { + case USART_TRANSCEIVER_RX: + /* Enable RX */ + usart_hw->CTRLB.reg |= SERCOM_USART_CTRLB_RXEN; + module->receiver_enabled = true; + break; + + case USART_TRANSCEIVER_TX: + /* Enable TX */ + usart_hw->CTRLB.reg |= SERCOM_USART_CTRLB_TXEN; + module->transmitter_enabled = true; + break; + } + _usart_wait_for_sync(module); +} + +/** + * \brief Disable Transceiver + * + * Disable the given transceiver (RX or TX). + * + * \param[in] module Pointer to USART software instance struct + * \param[in] transceiver_type Transceiver type + */ +static inline void usart_disable_transceiver( + struct usart_module *const module, + enum usart_transceiver_type transceiver_type) +{ + /* Sanity check arguments */ + Assert(module); + Assert(module->hw); + + /* Get a pointer to the hardware module instance */ + SercomUsart *const usart_hw = &(module->hw->USART); + + /* Wait until synchronization is complete */ + _usart_wait_for_sync(module); + + switch (transceiver_type) { + case USART_TRANSCEIVER_RX: + /* Disable RX */ + usart_hw->CTRLB.reg &= ~SERCOM_USART_CTRLB_RXEN; + module->receiver_enabled = false; + break; + + case USART_TRANSCEIVER_TX: + /* Disable TX */ + usart_hw->CTRLB.reg &= ~SERCOM_USART_CTRLB_TXEN; + module->transmitter_enabled = false; + break; + } +} + +/** @} */ + +#ifdef FEATURE_USART_LIN_MASTER +/** + * \name LIN Master Command and Status + * @{ + */ + +/** + * \brief Sending LIN command. + * + * Sending LIN command. + * + * \param[in] module Pointer to USART software instance struct. + * \param[in] cmd Cammand type. + */ +static inline void lin_master_send_cmd( + struct usart_module *const module, + enum lin_master_cmd cmd) +{ + SercomUsart *const usart_hw = &(module->hw->USART); + _usart_wait_for_sync(module); + usart_hw->CTRLB.reg |= cmd; +} + +/** + * \brief Get LIN transmission status. + * + * Get LIN transmission status. + * + * \param[in] module Pointer to USART software instance struct. + * + * \return Status of LIN master transmission. + * \retval true Data transmission completed + * \retval false Transmission is ongoing + */ +static inline bool lin_master_transmission_status(struct usart_module *const module) +{ + SercomUsart *const usart_hw = &(module->hw->USART); + return ((usart_hw->STATUS.reg & SERCOM_USART_STATUS_TXE)? true:false); +} + +/** @} */ +#endif + +#ifdef __cplusplus +} +#endif + +/** @} */ + +/** +* \page asfdoc_sam0_sercom_usart_extra Extra Information for SERCOM USART Driver +* +* \section asfdoc_sam0_sercom_usart_extra_acronyms Acronyms +* +* Below is a table listing the acronyms used in this module, along with their +* intended meanings. +* +* <table> +* <tr> +* <th>Acronym</th> +* <th>Description</th> +* </tr> +* <tr> +* <td>SERCOM</td> +* <td>Serial Communication Interface</td> +* </tr> +* <tr> +* <td>USART</td> +* <td>Universal Synchronous and Asynchronous Serial Receiver and Transmitter</td> +* </tr> +* <tr> +* <td>LSB</td> +* <td>Least Significant Bit</td> +* </tr> +* <tr> +* <td>MSB</td> +* <td>Most Significant Bit</td> +* </tr> +* <tr> +* <td>DMA</td> +* <td>Direct Memory Access</td> +* </tr> +* </table> +* +* +* \section asfdoc_sam0_sercom_usart_extra_dependencies Dependencies +* This driver has the following dependencies: +* +* - \ref asfdoc_sam0_system_pinmux_group "System Pin Multiplexer Driver" +* - \ref asfdoc_sam0_system_clock_group "System clock configuration" +* +* +* \section asfdoc_sam0_sercom_usart_extra_errata Errata +* There are no errata related to this driver. +* +* +* \section asfdoc_sam0_sercom_usart_extra_history Module History +* An overview of the module history is presented in the table below, with +* details on the enhancements and fixes made to the module since its first +* release. The current version of this corresponds to the newest version in +* the table. +* + * <table> + * <tr> + * <th>Changelog</th> + * </tr> + * <tr> + * <td>Added new feature as below: + * \li LIN master + * \li RS485 + * </tr> + * <tr> + * <td>Added new feature as below: + * \li Oversample + * \li Buffer overflow notification + * \li Irda + * \li Lin slave + * \li Start frame detection + * \li Hardware flow control + * \li Collision detection + * \li DMA support </td> + * </tr> + * <tr> + * <td>\li Added new \c transmitter_enable and \c receiver_enable Boolean + * values to \c struct usart_config + * \li Altered \c usart_write_* and usart_read_* functions to abort with + * an error code if the relevant transceiver is not enabled + * \li Fixed \c usart_write_buffer_wait() and \c usart_read_buffer_wait() + * not aborting correctly when a timeout condition occurs</td> + * </tr> + * <tr> + * <td>Initial Release</td> + * </tr> + * </table> +*/ + +/** + * \page asfdoc_sam0_sercom_usart_exqsg Examples for SERCOM USART Driver + * + * This is a list of the available Quick Start guides (QSGs) and example + * applications for \ref asfdoc_sam0_sercom_usart_group. QSGs are simple examples with + * step-by-step instructions to configure and use this driver in a selection of + * use cases. Note that QSGs can be compiled as a standalone application or be + * added to the user application. + * + * - \subpage asfdoc_sam0_sercom_usart_basic_use_case + * \if USART_CALLBACK_MODE + * - \subpage asfdoc_sam0_sercom_usart_callback_use_case + * \endif + * - \subpage asfdoc_sam0_sercom_usart_dma_use_case + * - \subpage asfdoc_sam0_sercom_usart_lin_use_case + */ + +/** + * \page asfdoc_sam0_sercom_usart_mux_settings SERCOM USART MUX Settings + * + * The following lists the possible internal SERCOM module pad function + * assignments, for the four SERCOM pads when in USART mode. Note that this is + * in addition to the physical GPIO pin MUX of the device, and can be used in + * conjunction to optimize the serial data pin-out. + * + * When TX and RX are connected to the same pin, the USART will operate in + * half-duplex mode if both the transmitter and receivers are enabled. + * + * \note When RX and XCK are connected to the same pin, the receiver must not + * be enabled if the USART is configured to use an external clock. + * + * + * <table> + * <tr> + * <th>MUX/Pad</th> + * <th>PAD 0</th> + * <th>PAD 1</th> + * <th>PAD 2</th> + * <th>PAD 3</th> + * </tr> + * <tr> + * <td>RX_0_TX_0_XCK_1</td> + * <td>TX / RX</td> + * <td>XCK</td> + * <td>-</td> + * <td>-</td> + * </tr> + * <tr> + * <td>RX_0_TX_2_XCK_3</td> + * <td>RX</td> + * <td>-</td> + * <td>TX</td> + * <td>XCK</td> + * </tr> + * <tr> + * <td>RX_1_TX_0_XCK_1</td> + * <td>TX</td> + * <td>RX / XCK</td> + * <td>-</td> + * <td>-</td> + * </tr> + * <tr> + * <td>RX_1_TX_2_XCK_3</td> + * <td>-</td> + * <td>RX</td> + * <td>TX</td> + * <td>XCK</td> + * </tr> + * <tr> + * <td>RX_2_TX_0_XCK_1</td> + * <td>TX</td> + * <td>XCK</td> + * <td>RX</td> + * <td>-</td> + * </tr> + * <tr> + * <td>RX_2_TX_2_XCK_3</td> + * <td>-</td> + * <td>-</td> + * <td>TX / RX</td> + * <td>XCK</td> + * </tr> + * <tr> + * <td>RX_3_TX_0_XCK_1</td> + * <td>TX</td> + * <td>XCK</td> + * <td>-</td> + * <td>RX</td> + * </tr> + * <tr> + * <td>RX_3_TX_2_XCK_3</td> + * <td>-</td> + * <td>-</td> + * <td>TX</td> + * <td>RX / XCK</td> + * </tr> + * </table> + * + * \page asfdoc_sam0_sercom_usart_document_revision_history Document Revision History + * + * <table> + * <tr> + * <th>Doc. Rev.</td> + * <th>Date</td> + * <th>Comments</td> + * </tr> + * <tr> + * <td>42118F</td> + * <td>06/2015</td> + * <td>Add support for SAML21, SAMDAx, and SAMC20/C21.</td> + * </tr> + * <tr> + * <td>42118E</td> + * <td>12/2014</td> + * <td>Add support for SAMR21 and SAMD10/D11.</td> + * </tr> + * <tr> + * <td>42118D</td> + * <td>01/2014</td> + * <td>Add support for SAMD21.</td> + * </tr> + * <tr> + * <td>42118C</td> + * <td>10/2013</td> + * <td>Replaced the pad multiplexing documentation with a condensed table.</td> + * </tr> + * <tr> + * <td>42118B</td> + * <td>06/2013</td> + * <td>Corrected documentation typos.</td> + * </tr> + * <tr> + * <td>42118A</td> + * <td>06/2013</td> + * <td>Initial release</td> + * </tr> + * </table> + */ +#endif /* USART_H_INCLUDED */