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/*
* FreeRTOS Kernel V10.4.0
* 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!
*/
/*
* A simple example that shows a stream buffer being used to pass data from an
* interrupt to a task.
*
* There are two strings, pcStringToSend and pcStringToReceive, where
* pcStringToReceive is a substring of pcStringToSend. The interrupt sends
* a few bytes of pcStringToSend to a stream buffer ever few times that it
* executes. A task reads the bytes from the stream buffer, looking for the
* substring, and flagging an error if the received data is invalid.
*/
/* Standard includes. */
#include "stdio.h"
#include "string.h"
/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "stream_buffer.h"
/* Demo app includes. */
#include "StreamBufferInterrupt.h"
#define sbiSTREAM_BUFFER_LENGTH_BYTES ( ( size_t ) 100 )
#define sbiSTREAM_BUFFER_TRIGGER_LEVEL_10 ( ( BaseType_t ) 10 )
/*-----------------------------------------------------------*/
/* Implements the task that receives a stream of bytes from the interrupt. */
static void prvReceivingTask( void *pvParameters );
/*-----------------------------------------------------------*/
/* The stream buffer that is used to send data from an interrupt to the task. */
static StreamBufferHandle_t xStreamBuffer = NULL;
/* The string that is sent from the interrupt to the task four bytes at a
time. Must be multiple of 4 bytes long as the ISR sends 4 bytes at a time*/
static const char * pcStringToSend = "_____Hello FreeRTOS_____";
/* The string to task is looking for, which must be a substring of
pcStringToSend. */
static const char * pcStringToReceive = "Hello FreeRTOS";
/* Set to pdFAIL if anything unexpected happens. */
static BaseType_t xDemoStatus = pdPASS;
/* Incremented each time pcStringToReceive is correctly received, provided no
errors have occurred. Used so the check task can check this task is still
running as expected. */
static uint32_t ulCycleCount = 0;
/*-----------------------------------------------------------*/
void vStartStreamBufferInterruptDemo( void )
{
/* Create the stream buffer that sends data from the interrupt to the
task, and create the task. */
xStreamBuffer = xStreamBufferCreate( /* The buffer length in bytes. */
sbiSTREAM_BUFFER_LENGTH_BYTES,
/* The stream buffer's trigger level. */
sbiSTREAM_BUFFER_TRIGGER_LEVEL_10 );
xTaskCreate( prvReceivingTask, /* The function that implements the task. */
"StrIntRx", /* Human readable name for the task. */
configMINIMAL_STACK_SIZE, /* Stack size (in words!). */
NULL, /* Task parameter is not used. */
tskIDLE_PRIORITY + 2, /* The priority at which the task is created. */
NULL ); /* No use for the task handle. */
}
/*-----------------------------------------------------------*/
static void prvReceivingTask( void *pvParameters )
{
char cRxBuffer[ 20 ];
BaseType_t xNextByte = 0;
/* Remove warning about unused parameters. */
( void ) pvParameters;
/* Make sure the string will fit in the Rx buffer, including the NULL
terminator. */
configASSERT( sizeof( cRxBuffer ) > strlen( pcStringToReceive ) );
/* Make sure the stream buffer has been created. */
configASSERT( xStreamBuffer != NULL );
/* Start with the Rx buffer in a known state. */
memset( cRxBuffer, 0x00, sizeof( cRxBuffer ) );
for( ;; )
{
/* Keep receiving characters until the end of the string is received.
Note: An infinite block time is used to simplify the example. Infinite
block times are not recommended in production code as they do not allow
for error recovery. */
xStreamBufferReceive( /* The stream buffer data is being received from. */
xStreamBuffer,
/* Where to place received data. */
( void * ) &( cRxBuffer[ xNextByte ] ),
/* The number of bytes to receive. */
sizeof( char ),
/* The time to wait for the next data if the buffer
is empty. */
portMAX_DELAY );
/* If xNextByte is 0 then this task is looking for the start of the
string, which is 'H'. */
if( xNextByte == 0 )
{
if( cRxBuffer[ xNextByte ] == 'H' )
{
/* The start of the string has been found. Now receive
characters until the end of the string is found. */
xNextByte++;
}
}
else
{
/* Receiving characters while looking for the end of the string,
which is an 'S'. */
if( cRxBuffer[ xNextByte ] == 'S' )
{
/* The string has now been received. Check its validity. */
if( strcmp( cRxBuffer, pcStringToReceive ) != 0 )
{
xDemoStatus = pdFAIL;
}
/* Return to start looking for the beginning of the string
again. */
memset( cRxBuffer, 0x00, sizeof( cRxBuffer ) );
xNextByte = 0;
/* Increment the cycle count as an indication to the check task
that this demo is still running. */
if( xDemoStatus == pdPASS )
{
ulCycleCount++;
}
}
else
{
/* Receive the next character the next time around, while
continuing to look for the end of the string. */
xNextByte++;
configASSERT( ( size_t ) xNextByte < sizeof( cRxBuffer ) );
}
}
}
}
/*-----------------------------------------------------------*/
void vBasicStreamBufferSendFromISR( void )
{
static size_t xNextByteToSend = 0;
const BaseType_t xCallsBetweenSends = 100, xBytesToSend = 4;
static BaseType_t xCallCount = 0;
/* Is it time to write to the stream buffer again? */
xCallCount++;
if( xCallCount > xCallsBetweenSends )
{
xCallCount = 0;
/* Send the next four bytes to the stream buffer. */
xStreamBufferSendFromISR( xStreamBuffer,
( const void * ) ( pcStringToSend + xNextByteToSend ),
xBytesToSend,
NULL );
/* Send the next four bytes the next time around, wrapping to the start
of the string if necessary. */
xNextByteToSend += xBytesToSend;
if( xNextByteToSend >= strlen( pcStringToSend ) )
{
xNextByteToSend = 0;
}
}
}
/*-----------------------------------------------------------*/
BaseType_t xIsInterruptStreamBufferDemoStillRunning( void )
{
uint32_t ulLastCycleCount = 0;
/* Check the demo is still running. */
if( ulLastCycleCount == ulCycleCount )
{
xDemoStatus = pdFAIL;
}
else
{
ulLastCycleCount = ulCycleCount;
}
return xDemoStatus;
}
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