/* | |
* FreeRTOS Kernel V10.0.1 | |
* Copyright (C) 2017 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( 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, | |
( 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; | |
} | |