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385 lines
10 KiB
C
385 lines
10 KiB
C
/*
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%atmel_license%
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*/
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/** \addtogroup usart_module Working with USART
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* The USART driver provides the interface to configure and use the USART peripheral.\n
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*
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* The USART supports several kinds of comminication modes such as full-duplex asynchronous/
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* synchronous serial commnunication,RS485 with driver control signal,ISO7816,SPI and Test modes.
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*
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* To start a USART transfer with \ref AT91SAM3S_PDC "PDC" support, the user could follow these steps:
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* <ul>
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* <li> Configure USART with expected mode and baudrate(see \ref USART_Configure), which could be done by:
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* -# Resetting and disabling transmitter and receiver by setting US_CR(Control Register). </li>
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* -# Conifguring the USART in a specific mode by setting USART_MODE bits in US_MR(Mode Register) </li>
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* -# Setting baudrate which is different from mode to mode.
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</li>
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* <li> Enable transmitter or receiver respectively by set US_CR_TXEN or US_CR_RXEN in US_CR.</li>
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* <li> Read from or write to the peripheral with \ref USART_ReadBuffer or \ref USART_WriteBuffer.
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These operations could be done by polling or interruption. </li>
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* <li> For polling, check the status bit US_CSR_ENDRX/US_CSR_RXBUFF (READ) or US_CSR_ENDTX/
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US_CSR_TXBUFE (WRITE). </li>
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* <li> For interruption,"enable" the status bit through US_IER and
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realize the hanler with USARTx_IrqHandler according to IRQ vector
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table which is defined in board_cstartup_<toolchain>.c
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To enable the interruption of USART,it should be configured with priority and enabled first through
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NVIC .</li>
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* </ul>
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*
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* For more accurate information, please look at the USART section of the
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* Datasheet.
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*
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* Related files :\n
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* \ref usart.c\n
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* \ref usart.h\n
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*/
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/**
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* \file
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*
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* Implementation of USART (Universal Synchronous Asynchronous Receiver Transmitter)
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* controller.
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*
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*/
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/*------------------------------------------------------------------------------
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* Headers
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*------------------------------------------------------------------------------*/
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#include "chip.h"
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#include <assert.h>
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#include <string.h>
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/*----------------------------------------------------------------------------
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* Local definitions
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*----------------------------------------------------------------------------*/
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/*------------------------------------------------------------------------------
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* Exported functions
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*------------------------------------------------------------------------------*/
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/**
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* \brief Configures an USART peripheral with the specified parameters.
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*
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*
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* \param usart Pointer to the USART peripheral to configure.
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* \param mode Desired value for the USART mode register (see the datasheet).
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* \param baudrate Baudrate at which the USART should operate (in Hz).
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* \param masterClock Frequency of the system master clock (in Hz).
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*/
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void USART_Configure(Usart *usart,
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uint32_t mode,
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uint32_t baudrate,
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uint32_t masterClock)
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{
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/* Reset and disable receiver & transmitter*/
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usart->US_CR = US_CR_RSTRX | US_CR_RSTTX
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| US_CR_RXDIS | US_CR_TXDIS;
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/* Configure mode*/
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usart->US_MR = mode;
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/* Configure baudrate*/
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/* Asynchronous, no oversampling*/
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if ( ((mode & US_MR_SYNC) == 0) && ((mode & US_MR_OVER) == 0) )
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{
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usart->US_BRGR = (masterClock / baudrate) / 16;
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}
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if( ((mode & US_MR_USART_MODE_SPI_MASTER) == US_MR_USART_MODE_SPI_MASTER)
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|| ((mode & US_MR_SYNC) == US_MR_SYNC))
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{
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if( (mode & US_MR_USCLKS_Msk) == US_MR_USCLKS_MCK)
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{
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usart->US_BRGR = masterClock / baudrate;
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}
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else
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{
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if ( (mode & US_MR_USCLKS_DIV) == US_MR_USCLKS_DIV)
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{
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usart->US_BRGR = masterClock / baudrate / 8;
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}
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}
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}
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/* TODO other modes*/
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}
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/**
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* \brief Enables or disables the transmitter of an USART peripheral.
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*
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*
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* \param usart Pointer to an USART peripheral
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* \param enabled If true, the transmitter is enabled; otherwise it is
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* disabled.
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*/
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void USART_SetTransmitterEnabled(Usart *usart, uint8_t enabled)
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{
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if (enabled) {
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usart->US_CR = US_CR_TXEN;
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}
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else {
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usart->US_CR = US_CR_TXDIS;
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}
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}
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/**
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* \brief Enables or disables the receiver of an USART peripheral
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*
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*
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* \param usart Pointer to an USART peripheral
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* \param enabled If true, the receiver is enabled; otherwise it is disabled.
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*/
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void USART_SetReceiverEnabled(Usart *usart,
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uint8_t enabled)
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{
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if (enabled) {
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usart->US_CR = US_CR_RXEN;
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}
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else {
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usart->US_CR = US_CR_RXDIS;
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}
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}
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/**
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* \brief Sends one packet of data through the specified USART peripheral. This
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* function operates synchronously, so it only returns when the data has been
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* actually sent.
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*
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*
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* \param usart Pointer to an USART peripheral.
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* \param data Data to send including 9nth bit and sync field if necessary (in
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* the same format as the US_THR register in the datasheet).
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* \param timeOut Time out value (0 = no timeout).
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*/
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void USART_Write(
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Usart *usart,
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uint16_t data,
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volatile uint32_t timeOut)
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{
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if (timeOut == 0) {
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while ((usart->US_CSR & US_CSR_TXEMPTY) == 0);
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}
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else {
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while ((usart->US_CSR & US_CSR_TXEMPTY) == 0) {
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if (timeOut == 0) {
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// TRACE_ERROR("USART_Write: Timed out.\n\r");
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return;
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}
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timeOut--;
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}
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}
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usart->US_THR = data;
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}
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/**
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* \brief Sends the contents of a data buffer through the specified USART peripheral.
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* This function returns immediately (1 if the buffer has been queued, 0
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* otherwise); poll the ENDTX and TXBUFE bits of the USART status register
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* to check for the transfer completion.
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*
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* \param usart Pointer to an USART peripheral.
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* \param buffer Pointer to the data buffer to send.
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* \param size Size of the data buffer (in bytes).
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*/
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uint8_t USART_WriteBuffer(
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Usart *usart,
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void *buffer,
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uint32_t size)
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{
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/* Check if the first PDC bank is free*/
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if ((usart->US_TCR == 0) && (usart->US_TNCR == 0)) {
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usart->US_TPR = (uint32_t) buffer;
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usart->US_TCR = size;
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usart->US_PTCR = US_PTCR_TXTEN;
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return 1;
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}
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/* Check if the second PDC bank is free*/
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else if (usart->US_TNCR == 0) {
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usart->US_TNPR = (uint32_t) buffer;
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usart->US_TNCR = size;
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return 1;
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}
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else {
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return 0;
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}
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}
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/**
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* \brief Reads and return a packet of data on the specified USART peripheral. This
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* function operates asynchronously, so it waits until some data has been
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* received.
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*
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* \param usart Pointer to an USART peripheral.
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* \param timeOut Time out value (0 -> no timeout).
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*/
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uint16_t USART_Read(
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Usart *usart,
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volatile uint32_t timeOut)
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{
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if (timeOut == 0) {
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while ((usart->US_CSR & US_CSR_RXRDY) == 0);
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}
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else {
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while ((usart->US_CSR & US_CSR_RXRDY) == 0) {
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if (timeOut == 0) {
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// TRACE_ERROR( "USART_Read: Timed out.\n\r" ) ;
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return 0;
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}
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timeOut--;
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}
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}
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return usart->US_RHR;
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}
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/**
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* \brief Reads data from an USART peripheral, filling the provided buffer until it
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* becomes full. This function returns immediately with 1 if the buffer has
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* been queued for transmission; otherwise 0.
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*
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* \param usart Pointer to an USART peripheral.
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* \param buffer Pointer to the buffer where the received data will be stored.
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* \param size Size of the data buffer (in bytes).
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*/
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uint8_t USART_ReadBuffer(Usart *usart,
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void *buffer,
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uint32_t size)
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{
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/* Check if the first PDC bank is free*/
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if ((usart->US_RCR == 0) && (usart->US_RNCR == 0)) {
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usart->US_RPR = (uint32_t) buffer;
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usart->US_RCR = size;
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usart->US_PTCR = US_PTCR_RXTEN;
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return 1;
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}
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/* Check if the second PDC bank is free*/
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else if (usart->US_RNCR == 0) {
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usart->US_RNPR = (uint32_t) buffer;
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usart->US_RNCR = size;
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return 1;
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}
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else {
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return 0;
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}
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}
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/**
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* \brief Returns 1 if some data has been received and can be read from an USART;
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* otherwise returns 0.
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*
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* \param usart Pointer to an Usart instance.
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*/
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uint8_t USART_IsDataAvailable(Usart *usart)
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{
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if ((usart->US_CSR & US_CSR_RXRDY) != 0) {
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return 1;
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}
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else {
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return 0;
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}
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}
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/**
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* \brief Sets the filter value for the IRDA demodulator.
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*
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* \param pUsart Pointer to an Usart instance.
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* \param filter Filter value.
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*/
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void USART_SetIrdaFilter(Usart *pUsart, uint8_t filter)
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{
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assert( pUsart != NULL ) ;
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pUsart->US_IF = filter;
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}
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/**
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* \brief Sends one packet of data through the specified USART peripheral. This
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* function operates synchronously, so it only returns when the data has been
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* actually sent.
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*
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* \param usart Pointer to an USART peripheral.
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* \param c Character to send
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*/
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void USART_PutChar(
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Usart *usart,
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uint8_t c)
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{
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/* Wait for the transmitter to be ready*/
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while ((usart->US_CSR & US_CSR_TXEMPTY) == 0);
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/* Send character*/
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usart->US_THR = c;
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/* Wait for the transfer to complete*/
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while ((usart->US_CSR & US_CSR_TXEMPTY) == 0);
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}
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/**
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* \brief Return 1 if a character can be read in USART
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*/
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uint32_t USART_IsRxReady(Usart *usart)
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{
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return (usart->US_CSR & US_CSR_RXRDY);
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}
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/**
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* \brief Get present status
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*/
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uint32_t USART_GetStatus(Usart *usart)
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{
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return usart->US_CSR;
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}
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/**
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* \brief Enable interrupt
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*/
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void USART_EnableIt(Usart *usart,uint32_t mode)
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{
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usart->US_IER = mode;
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}
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/**
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* \brief Disable interrupt
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*/
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void USART_DisableIt(Usart *usart,uint32_t mode)
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{
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usart->US_IDR = mode;
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}
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/**
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* \brief Reads and returns a character from the USART.
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*
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* \note This function is synchronous (i.e. uses polling).
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* \param usart Pointer to an USART peripheral.
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* \return Character received.
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*/
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uint8_t USART_GetChar(Usart *usart)
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{
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while ((usart->US_CSR & US_CSR_RXRDY) == 0);
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return usart->US_RHR;
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}
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