2 * FreeRTOS Kernel V10.1.1
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3 * Copyright (C) 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software.
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 * http://www.FreeRTOS.org
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23 * http://aws.amazon.com/freertos
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25 * 1 tab == 4 spaces!
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29 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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32 /* Library includes. */
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37 /* Scheduler includes. */
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38 #include "FreeRTOS.h"
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41 /* Demo application includes. */
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44 #define UART0_Rx_Pin ( 0x0001<< 8 )
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45 #define UART0_Tx_Pin ( 0x0001<< 9 )
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47 #define serINVALID_QUEUE ( ( QueueHandle_t ) 0 )
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48 #define serNO_BLOCK ( ( TickType_t ) 0 )
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50 /* Macros to turn on and off the Tx empty interrupt. */
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51 #define serINTERRUPT_ON() UART0->IER |= UART_TxHalfEmpty
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52 #define serINTERRUPT_OFF() UART0->IER &= ~UART_TxHalfEmpty
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54 /*-----------------------------------------------------------*/
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56 /* Queues used to hold received characters, and characters waiting to be
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58 static QueueHandle_t xRxedChars;
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59 static QueueHandle_t xCharsForTx;
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61 /*-----------------------------------------------------------*/
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63 /* Interrupt entry point written in the assembler file serialISR.s79. */
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64 extern void vSerialISREntry( void );
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66 /* The interrupt service routine - called from the assembly entry point. */
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67 __arm void vSerialISR( void );
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69 /*-----------------------------------------------------------*/
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72 * See the serial2.h header file.
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74 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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76 xComPortHandle xReturn;
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78 /* Create the queues used to hold Rx and Tx characters. */
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79 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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80 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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82 /* If the queues were created correctly then setup the serial port
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84 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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86 portENTER_CRITICAL();
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88 /* Setup the UART port pins. */
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89 GPIO_Config( GPIO0, UART0_Tx_Pin, GPIO_AF_PP );
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90 GPIO_Config( GPIO0, UART0_Rx_Pin, GPIO_IN_TRI_CMOS );
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92 /* Configure the UART. */
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93 UART_OnOffConfig( UART0, ENABLE );
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94 UART_FifoConfig( UART0, DISABLE );
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95 UART_FifoReset( UART0, UART_RxFIFO );
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96 UART_FifoReset( UART0, UART_TxFIFO );
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97 UART_LoopBackConfig(UART0, DISABLE );
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98 UART_Config( UART0, ulWantedBaud, UART_NO_PARITY, UART_1_StopBits, UARTM_8D );
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99 UART_RxConfig( UART0, ENABLE );
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101 /* Configure the IEC for the UART interrupts. */
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102 EIC_IRQChannelPriorityConfig( UART0_IRQChannel, 1 );
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103 EIC_IRQChannelConfig( UART0_IRQChannel, ENABLE );
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104 EIC_IRQConfig( ENABLE );
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105 UART_ItConfig( UART0, UART_RxBufFull, ENABLE );
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107 portEXIT_CRITICAL();
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111 xReturn = ( xComPortHandle ) 0;
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114 /* This demo file only supports a single port but we have to return
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115 something to comply with the standard demo header file. */
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118 /*-----------------------------------------------------------*/
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120 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
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122 /* The port handle is not required as this driver only supports one port. */
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125 /* Get the next character from the buffer. Return false if no characters
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126 are available, or arrive before xBlockTime expires. */
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127 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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136 /*-----------------------------------------------------------*/
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138 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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140 signed char *pxNext;
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142 /* A couple of parameters that this port does not use. */
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143 ( void ) usStringLength;
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146 /* NOTE: This implementation does not handle the queue being full as no
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147 block time is used! */
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149 /* The port handle is not required as this driver only supports UART0. */
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152 /* Send each character in the string, one at a time. */
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153 pxNext = ( signed char * ) pcString;
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156 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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160 /*-----------------------------------------------------------*/
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162 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )
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164 /* Place the character in the queue of characters to be transmitted. */
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165 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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170 /* Turn on the Tx interrupt so the ISR will remove the character from the
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171 queue and send it. This does not need to be in a critical section as
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172 if the interrupt has already removed the character the next interrupt
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173 will simply turn off the Tx interrupt again. */
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178 /*-----------------------------------------------------------*/
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180 void vSerialClose( xComPortHandle xPort )
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182 /* Not supported as not required by the demo application. */
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184 /*-----------------------------------------------------------*/
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186 /* Serial port ISR. This can cause a context switch so is not defined as a
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187 standard ISR using the __irq keyword. Instead a wrapper function is defined
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188 within serialISR.s79 which in turn calls this function. See the port
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189 documentation on the FreeRTOS.org website for more information. */
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190 __arm void vSerialISR( void )
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192 unsigned short usStatus;
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194 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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196 /* What caused the interrupt? */
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197 usStatus = UART_FlagStatus( UART0 );
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199 if( usStatus & UART_TxHalfEmpty )
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201 /* The interrupt was caused by the THR becoming empty. Are there any
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202 more characters to transmit? */
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203 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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205 /* A character was retrieved from the queue so can be sent to the
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207 UART0->TxBUFR = cChar;
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211 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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212 serINTERRUPT_OFF();
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216 if( usStatus & UART_RxBufFull )
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218 /* The interrupt was caused by a character being received. Grab the
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219 character from the RHR and place it in the queue of received
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221 cChar = UART0->RxBUFR;
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222 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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225 /* If a task was woken by either a character being received or a character
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226 being transmitted then we may need to switch to another task. */
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227 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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229 /* End the interrupt in the EIC. */
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