312 lines
11 KiB
C
312 lines
11 KiB
C
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/*
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* FreeRTOS Kernel V10.2.1
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* Copyright (C) 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* http://www.FreeRTOS.org
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* http://aws.amazon.com/freertos
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*
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* 1 tab == 4 spaces!
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*/
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/*
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* Creates a task and a timer that operate on an interrupt driven serial port.
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* This demo assumes that the characters transmitted on a port will also be
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* received on the same port. Therefore, the UART must either be connected to
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* an echo server, or the uart connector must have a loopback connector fitted.
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* See http://www.serialporttool.com/CommEcho.htm for a suitable echo server
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* for Windows hosts.
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*
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* The timer sends a string to the UART, toggles an LED, then resets itself by
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* changing its own period. The period is calculated as a pseudo random number
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* between comTX_MAX_BLOCK_TIME and comTX_MIN_BLOCK_TIME.
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*
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* The task blocks on an Rx queue waiting for a character to become available.
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* Received characters are checked to ensure they match those transmitted by the
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* Tx timer. An error is latched if characters are missing, incorrect, or
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* arrive too slowly.
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*
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* How characters are actually transmitted and received is port specific. Demos
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* that include this test/demo file will provide example drivers. The Tx timer
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* executes in the context of the timer service (daemon) task, and must
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* therefore never attempt to block.
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*
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*/
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/* Scheduler include files. */
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#include <stdlib.h>
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#include <string.h>
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#include "FreeRTOS.h"
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#include "task.h"
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#include "timers.h"
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#ifndef configUSE_TIMERS
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#error This demo uses timers. configUSE_TIMERS must be set to 1 in FreeRTOSConfig.h.
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#endif
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#if configUSE_TIMERS != 1
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#error This demo uses timers. configUSE_TIMERS must be set to 1 in FreeRTOSConfig.h.
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#endif
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/* Demo program include files. */
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#include "serial.h"
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#include "comtest_strings.h"
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#include "partest.h"
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/* The size of the stack given to the Rx task. */
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#define comSTACK_SIZE configMINIMAL_STACK_SIZE
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/* See the comment above the declaraction of the uxBaseLED variable. */
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#define comTX_LED_OFFSET ( 0 )
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#define comRX_LED_OFFSET ( 1 )
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/* The Tx timer transmits the sequence of characters at a pseudo random
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interval that is capped between comTX_MAX_BLOCK_TIME and
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comTX_MIN_BLOCK_TIME. */
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#define comTX_MAX_BLOCK_TIME ( ( TickType_t ) 0x96 )
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#define comTX_MIN_BLOCK_TIME ( ( TickType_t ) 0x32 )
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#define comOFFSET_TIME ( ( TickType_t ) 3 )
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/* States for the simple state machine implemented in the Rx task. */
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#define comtstWAITING_START_OF_STRING 0
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#define comtstWAITING_END_OF_STRING 1
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/* A short delay in ticks - this delay is used to allow the Rx queue to fill up
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a bit so more than one character can be processed at a time. This is relative
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to comTX_MIN_BLOCK_TIME to ensure it is never longer than the shortest gap
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between transmissions. It could be worked out more scientifically from the
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baud rate being used. */
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#define comSHORT_DELAY ( comTX_MIN_BLOCK_TIME >> ( TickType_t ) 2 )
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/* The string that is transmitted and received. */
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#define comTRANSACTED_STRING "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"
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/* A block time of 0 simply means "don't block". */
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#define comtstDONT_BLOCK ( TickType_t ) 0
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/* Handle to the com port used by both tasks. */
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static xComPortHandle xPort = NULL;
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/* The callback function allocated to the transmit timer, as described in the
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comments at the top of this file. */
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static void prvComTxTimerCallback( TimerHandle_t xTimer );
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/* The receive task as described in the comments at the top of this file. */
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static void vComRxTask( void *pvParameters );
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/* The Rx task will toggle LED ( uxBaseLED + comRX_LED_OFFSET). The Tx task
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will toggle LED ( uxBaseLED + comTX_LED_OFFSET ). */
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static UBaseType_t uxBaseLED = 0;
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/* The Rx task toggles uxRxLoops on each successful iteration of its defined
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function - provided no errors have ever been latched. If this variable stops
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incrementing, then an error has occurred. */
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static volatile UBaseType_t uxRxLoops = 0UL;
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/* The timer used to periodically transmit the string. This is the timer that
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has prvComTxTimerCallback allocated to it as its callback function. */
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static TimerHandle_t xTxTimer = NULL;
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/* The string length is held at file scope so the Tx timer does not need to
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calculate it each time it executes. */
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static size_t xStringLength = 0U;
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/*-----------------------------------------------------------*/
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void vStartComTestStringsTasks( UBaseType_t uxPriority, uint32_t ulBaudRate, UBaseType_t uxLED )
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{
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/* Store values that are used at run time. */
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uxBaseLED = uxLED;
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/* Calculate the string length here, rather than each time the Tx timer
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executes. */
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xStringLength = strlen( comTRANSACTED_STRING );
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/* Include the null terminator in the string length as this is used to
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detect the end of the string in the Rx task. */
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xStringLength++;
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/* Initialise the com port, then spawn the Rx task and create the Tx
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timer. */
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xSerialPortInitMinimal( ulBaudRate, ( xStringLength * 2U ) );
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/* Create the Rx task and the Tx timer. The timer is started from the
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Rx task. */
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xTaskCreate( vComRxTask, "COMRx", comSTACK_SIZE, NULL, uxPriority, ( TaskHandle_t * ) NULL );
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xTxTimer = xTimerCreate( "TxTimer", comTX_MIN_BLOCK_TIME, pdFALSE, NULL, prvComTxTimerCallback );
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configASSERT( xTxTimer );
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}
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/*-----------------------------------------------------------*/
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static void prvComTxTimerCallback( TimerHandle_t xTimer )
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{
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TickType_t xTimeToWait;
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/* The parameter is not used in this case. */
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( void ) xTimer;
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/* Send the string. How this is actually performed depends on the
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sample driver provided with this demo. However - as this is a timer,
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it executes in the context of the timer task and therefore must not
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block. */
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vSerialPutString( xPort, comTRANSACTED_STRING, xStringLength );
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/* Toggle an LED to give a visible indication that another transmission
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has been performed. */
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vParTestToggleLED( uxBaseLED + comTX_LED_OFFSET );
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/* Wait a pseudo random time before sending the string again. */
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xTimeToWait = xTaskGetTickCount() + comOFFSET_TIME;
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/* Ensure the time to wait is not greater than comTX_MAX_BLOCK_TIME. */
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xTimeToWait %= comTX_MAX_BLOCK_TIME;
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/* Ensure the time to wait is not less than comTX_MIN_BLOCK_TIME. */
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if( xTimeToWait < comTX_MIN_BLOCK_TIME )
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{
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xTimeToWait = comTX_MIN_BLOCK_TIME;
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}
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/* Reset the timer to run again xTimeToWait ticks from now. This function
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is called from the context of the timer task, so the block time must not
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be anything other than zero. */
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xTimerChangePeriod( xTxTimer, xTimeToWait, comtstDONT_BLOCK );
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}
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/*-----------------------------------------------------------*/
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static void vComRxTask( void *pvParameters )
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{
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BaseType_t xState = comtstWAITING_START_OF_STRING, xErrorOccurred = pdFALSE;
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char *pcExpectedByte, cRxedChar;
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const xComPortHandle xPort = NULL;
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/* The parameter is not used in this example. */
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( void ) pvParameters;
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/* Start the Tx timer. This only needs to be started once, as it will
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reset itself thereafter. */
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xTimerStart( xTxTimer, portMAX_DELAY );
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/* The first expected Rx character is the first in the string that is
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transmitted. */
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pcExpectedByte = comTRANSACTED_STRING;
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for( ;; )
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{
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/* Wait for the next character. */
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if( xSerialGetChar( xPort, &cRxedChar, ( comTX_MAX_BLOCK_TIME * 2 ) ) == pdFALSE )
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{
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/* A character definitely should have been received by now. As a
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character was not received an error must have occurred (which might
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just be that the loopback connector is not fitted). */
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xErrorOccurred = pdTRUE;
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}
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switch( xState )
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{
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case comtstWAITING_START_OF_STRING:
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if( cRxedChar == *pcExpectedByte )
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{
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/* The received character was the first character of the
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string. Move to the next state to check each character
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as it comes in until the entire string has been received. */
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xState = comtstWAITING_END_OF_STRING;
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pcExpectedByte++;
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/* Block for a short period. This just allows the Rx queue
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to contain more than one character, and therefore prevent
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thrashing reads to the queue, and repetitive context
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switches as each character is received. */
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vTaskDelay( comSHORT_DELAY );
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}
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break;
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case comtstWAITING_END_OF_STRING:
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if( cRxedChar == *pcExpectedByte )
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{
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/* The received character was the expected character. Was
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it the last character in the string - i.e. the null
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terminator? */
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if( cRxedChar == 0x00 )
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{
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/* The entire string has been received. If no errors
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have been latched, then increment the loop counter to
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show this task is still healthy. */
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if( xErrorOccurred == pdFALSE )
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{
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uxRxLoops++;
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/* Toggle an LED to give a visible sign that a
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complete string has been received. */
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vParTestToggleLED( uxBaseLED + comRX_LED_OFFSET );
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}
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/* Go back to wait for the start of the next string. */
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pcExpectedByte = comTRANSACTED_STRING;
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xState = comtstWAITING_START_OF_STRING;
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}
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else
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{
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/* Wait for the next character in the string. */
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pcExpectedByte++;
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}
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}
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else
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{
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/* The character received was not that expected. */
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xErrorOccurred = pdTRUE;
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}
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break;
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default:
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/* Should not get here. Stop the Rx loop counter from
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incrementing to latch the error. */
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xErrorOccurred = pdTRUE;
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break;
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}
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}
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}
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/*-----------------------------------------------------------*/
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BaseType_t xAreComTestTasksStillRunning( void )
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{
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BaseType_t xReturn;
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/* If the count of successful reception loops has not changed than at
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some time an error occurred (i.e. a character was received out of sequence)
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and false is returned. */
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if( uxRxLoops == 0UL )
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{
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xReturn = pdFALSE;
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}
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else
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{
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xReturn = pdTRUE;
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}
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/* Reset the count of successful Rx loops. When this function is called
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again it should have been incremented again. */
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uxRxLoops = 0UL;
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return xReturn;
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}
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