2 * FreeRTOS Kernel V10.3.0
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3 * Copyright (C) 2020 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 /* Standard includes. */
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35 /* Scheduler includes. */
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36 #include "FreeRTOS.h"
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39 /* Demo application includes. */
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42 /*-----------------------------------------------------------*/
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44 /* Location of the COM0 registers. */
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45 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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47 /* Interrupt control macros. */
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48 #define serINTERRUPT_LEVEL ( 5 )
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49 #define vInterruptOn() AT91F_US_EnableIt( serCOM0, AT91C_US_TXRDY | AT91C_US_RXRDY )
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50 #define vInterruptOff() AT91F_US_DisableIt( serCOM0, AT91C_US_TXRDY )
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52 /* Misc constants. */
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53 #define serINVALID_QUEUE ( ( QueueHandle_t ) 0 )
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54 #define serHANDLE ( ( xComPortHandle ) 1 )
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55 #define serNO_BLOCK ( ( TickType_t ) 0 )
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56 #define serNO_TIMEGUARD ( ( unsigned long ) 0 )
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57 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned long ) 0 )
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60 /* Queues used to hold received characters, and characters waiting to be
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62 static QueueHandle_t xRxedChars;
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63 static QueueHandle_t xCharsForTx;
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65 /*-----------------------------------------------------------*/
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67 /* Interrupt entry point written in the assembler file serialISR.s79. */
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68 extern void vSerialISREntry( void );
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70 /* The interrupt service routine - called from the assembly entry point. */
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71 __arm void vSerialISR( void );
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73 /*-----------------------------------------------------------*/
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76 * See the serial2.h header file.
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78 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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80 xComPortHandle xReturn = serHANDLE;
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81 extern void ( vUART_ISR )( void );
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83 /* Create the queues used to hold Rx and Tx characters. */
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84 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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85 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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87 /* If the queues were created correctly then setup the serial port
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89 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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91 portENTER_CRITICAL();
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93 /* Enable the USART clock. */
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94 AT91F_PMC_EnablePeriphClock( AT91C_BASE_PMC, 1 << AT91C_ID_US0 );
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96 AT91F_PIO_CfgPeriph( AT91C_BASE_PIOA, ( ( unsigned long ) AT91C_PA5_RXD0 ) | ( ( unsigned long ) AT91C_PA6_TXD0 ), serNO_PERIPHERAL_B_SETUP );
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98 /* Set the required protocol. */
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99 AT91F_US_Configure( serCOM0, configCPU_CLOCK_HZ, AT91C_US_ASYNC_MODE, ulWantedBaud, serNO_TIMEGUARD );
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101 /* Enable Rx and Tx. */
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102 serCOM0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN;
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104 /* Enable the Rx interrupts. The Tx interrupts are not enabled
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105 until there are characters to be transmitted. */
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106 AT91F_US_EnableIt( serCOM0, AT91C_US_RXRDY );
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108 /* Enable the interrupts in the AIC. */
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109 AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_US0, serINTERRUPT_LEVEL, AT91C_AIC_SRCTYPE_INT_LEVEL_SENSITIVE, ( void (*)( void ) ) vSerialISREntry );
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110 AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_US0 );
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112 portEXIT_CRITICAL();
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116 xReturn = ( xComPortHandle ) 0;
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119 /* This demo file only supports a single port but we have to return
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120 something to comply with the standard demo header file. */
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123 /*-----------------------------------------------------------*/
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125 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
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127 /* The port handle is not required as this driver only supports one port. */
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130 /* Get the next character from the buffer. Return false if no characters
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131 are available, or arrive before xBlockTime expires. */
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132 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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141 /*-----------------------------------------------------------*/
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143 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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145 signed char *pxNext;
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147 /* A couple of parameters that this port does not use. */
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148 ( void ) usStringLength;
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151 /* NOTE: This implementation does not handle the queue being full as no
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152 block time is used! */
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154 /* The port handle is not required as this driver only supports UART0. */
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157 /* Send each character in the string, one at a time. */
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158 pxNext = ( signed char * ) pcString;
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161 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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165 /*-----------------------------------------------------------*/
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167 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )
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169 /* Place the character in the queue of characters to be transmitted. */
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170 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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175 /* Turn on the Tx interrupt so the ISR will remove the character from the
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176 queue and send it. This does not need to be in a critical section as
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177 if the interrupt has already removed the character the next interrupt
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178 will simply turn off the Tx interrupt again. */
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183 /*-----------------------------------------------------------*/
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185 void vSerialClose( xComPortHandle xPort )
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187 /* Not supported as not required by the demo application. */
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189 /*-----------------------------------------------------------*/
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191 /* Serial port ISR. This can cause a context switch so is not defined as a
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192 standard ISR using the __irq keyword. Instead a wrapper function is defined
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193 within serialISR.s79 which in turn calls this function. See the port
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194 documentation on the FreeRTOS.org website for more information. */
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195 __arm void vSerialISR( void )
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197 unsigned long ulStatus;
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199 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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201 /* What caused the interrupt? */
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202 ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
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204 if( ulStatus & AT91C_US_TXRDY )
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206 /* The interrupt was caused by the THR becoming empty. Are there any
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207 more characters to transmit? */
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208 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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210 /* A character was retrieved from the queue so can be sent to the
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212 serCOM0->US_THR = cChar;
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216 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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221 if( ulStatus & AT91C_US_RXRDY )
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223 /* The interrupt was caused by a character being received. Grab the
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224 character from the RHR and place it in the queue or received
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226 cChar = serCOM0->US_RHR;
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227 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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230 /* If a task was woken by either a character being received or a character
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231 being transmitted then we may need to switch to another task. */
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232 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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234 /* End the interrupt in the AIC. */
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235 AT91C_BASE_AIC->AIC_EOICR = 0;
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