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