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/*
* FreeRTOS V202104.00
* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* http://www.FreeRTOS.org
* http://aws.amazon.com/freertos
*
* 1 tab == 4 spaces!
*/
/*
BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
*NOTE* - This file is designed to test some of the RTOS features - it is
not intended to represent an efficient implementation!
*/
/* Standard includes. */
#include <stdlib.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "queue.h"
/* Demo application includes. */
#include "serial.h"
/* Hardware specifics. */
#define serRX_DATA_PIN ( 0x01 )
#define serTX_DATA_PIN ( 0x02 )
#define serCLOCK_Fxx_DIV_8 0x03
#define serUPWR ( 0x80 )
#define serUTXE ( 0x40 )
#define serURXE ( 0x20 )
#define serUCL ( 0x02 )
#define serLSB ( 0x10 )
/* Misc. */
#define serINVALID_QUEUE ( ( QueueHandle_t ) 0 )
#define serHANDLE ( ( xComPortHandle ) 1 )
#define serNO_BLOCK ( ( TickType_t ) 0 )
/*-----------------------------------------------------------*/
/* Queues used to hold received characters, and characters waiting to be
transmitted. */
static QueueHandle_t xRxedChars;
static QueueHandle_t xCharsForTx;
/*-----------------------------------------------------------*/
/* Interrupt entry point written in the assembler file serialISR.s85. */
extern void vSerialISREntry( void );
/* Flag to indicate whether or not there are characters already queued to send. */
static volatile unsigned long ulTxInProgress = pdFALSE;
/*-----------------------------------------------------------*/
/*
* See the serial2.h header file.
*/
xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
xComPortHandle xReturn = serHANDLE;
const unsigned long ulFuclk = ( configCPU_CLOCK_HZ / 2 ) / 8UL;
/* Create the queues used to hold Rx and Tx characters. */
xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
/* If the queues were created correctly then setup the serial port
hardware. */
if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
{
portENTER_CRITICAL();
{
/* Set the UART0 Rx and Tx pins to their alternative function. */
PMC3 |= ( serRX_DATA_PIN | serTX_DATA_PIN );
PM3 &= ~( serTX_DATA_PIN );
/* Setup clock for required baud. */
UD0CTL1 = serCLOCK_Fxx_DIV_8;
UD0CTL2 = ulFuclk / ( 2 * ulWantedBaud );
/* Enable, n81. */
UD0CTL0 = ( serUPWR | serUTXE | serURXE | serUCL | serLSB );
/* Enable interrupts for both Rx and Tx. */
UD0TIC = 0x07;
UD0RIC = 0x07;
ulTxInProgress = pdFALSE;
}
portEXIT_CRITICAL();
}
else
{
xReturn = ( xComPortHandle ) 0;
}
/* This demo file only supports a single port but we have to return
something to comply with the standard demo header file. */
return xReturn;
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
{
/* The port handle is not required as this driver only supports one port. */
( void ) pxPort;
/* Get the next character from the buffer. Return false if no characters
are available, or arrive before xBlockTime expires. */
if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
{
return pdTRUE;
}
else
{
return pdFALSE;
}
}
/*-----------------------------------------------------------*/
void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
{
signed char *pxNext;
/* A couple of parameters that this port does not use. */
( void ) usStringLength;
( void ) pxPort;
/* NOTE: This implementation does not handle the queue being full as no
block time is used! */
/* The port handle is not required as this driver only supports UART0. */
( void ) pxPort;
/* Send each character in the string, one at a time. */
pxNext = ( signed char * ) pcString;
while( *pxNext )
{
xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
pxNext++;
}
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )
{
portBASE_TYPE xReturn = pdPASS;
portENTER_CRITICAL();
{
/* There are currently no characters queued up to send so write the
character directly to the UART. */
if( ulTxInProgress == pdFALSE )
{
UD0TX = cOutChar;
ulTxInProgress = pdTRUE;
}
else
{
/* The UART is already busy so write the character to the Tx queue.
The queue is drained from within the Tx interrupt. */
if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
{
xReturn = pdFAIL;
}
}
}
portEXIT_CRITICAL();
return xReturn;
}
/*-----------------------------------------------------------*/
void vSerialClose( xComPortHandle xPort )
{
/* Not supported as not required by the demo application. */
}
/*-----------------------------------------------------------*/
/* Tx interrupt handler. This is called from the asm file wrapper. */
void vUARTTxISRHandler( void )
{
char cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
/* Are there any more characters queue to transmit? */
if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
{
/* Send the next character. */
UD0TX = cChar;
}
else
{
/* The UART is no longer active. */
ulTxInProgress = pdFALSE;
}
/* If reading a character from the Rx queue caused a task to unblock, and
the unblocked task has a priority higher than the currently running task,
then xHigherPriorityTaskWoken will have been set to true and a context
switch should occur now. */
portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
}
/*-----------------------------------------------------------*/
/* Rx interrupt handler. This is called from the asm file wrapper. */
void vUARTRxISRHandler( void )
{
char cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
/* Send the received character to the Rx queue. */
cChar = UD0RX;
xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
/* If sending a character to the Tx queue caused a task to unblock, and
the unblocked task has a priority higher than the currently running task,
then xHigherPriorityTaskWoken will have been set to true and a context
switch should occur now. */
portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
}
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