2 * FreeRTOS Kernel V10.0.0
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3 * Copyright (C) 2017 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. If you wish to use our Amazon
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14 * FreeRTOS name, please do so in a fair use way that does not cause confusion.
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16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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18 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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19 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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20 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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23 * http://www.FreeRTOS.org
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24 * http://aws.amazon.com/freertos
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26 * 1 tab == 4 spaces!
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30 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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33 /* Standard includes. */
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36 /* Scheduler includes. */
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37 #include "FreeRTOS.h"
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40 /* Demo application includes. */
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43 /* Library includes. */
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44 #include "usart/usart.h"
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45 #include "pmc/pmc.h"
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46 #include "irq/irq.h"
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47 #include "pio/pio.h"
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49 /*-----------------------------------------------------------*/
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51 /* Interrupt control macros. */
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52 #define serINTERRUPT_LEVEL ( 5 )
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53 #define vInterruptOn() BOARD_USART_BASE->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )
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54 #define vInterruptOff() BOARD_USART_BASE->US_IDR = AT91C_US_TXRDY
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56 /* Misc constants. */
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57 #define serINVALID_QUEUE ( ( QueueHandle_t ) 0 )
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58 #define serHANDLE ( ( xComPortHandle ) 1 )
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59 #define serNO_BLOCK ( ( TickType_t ) 0 )
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60 #define serNO_TIMEGUARD ( ( unsigned long ) 0 )
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61 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned long ) 0 )
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64 /* Queues used to hold received characters, and characters waiting to be
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66 static QueueHandle_t xRxedChars;
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67 static QueueHandle_t xCharsForTx;
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69 /*-----------------------------------------------------------*/
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71 /* The interrupt service routine - called from the assembly entry point. */
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72 void vSerialISR( void );
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74 /*-----------------------------------------------------------*/
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77 * See the serial2.h header file.
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79 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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81 xComPortHandle xReturn = serHANDLE;
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82 extern void ( vUART_ISR )( void );
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83 const Pin xUSART_Pins[] = { BOARD_PIN_USART_RXD, BOARD_PIN_USART_TXD };
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86 /* Create the queues used to hold Rx and Tx characters. */
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87 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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88 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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90 /* If the queues were created correctly then setup the serial port
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92 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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94 portENTER_CRITICAL();
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96 /* Enable the peripheral clock in the PMC. */
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97 PMC_EnablePeripheral( BOARD_ID_USART );
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99 /* Configure the USART. */
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100 USART_Configure( BOARD_USART_BASE, AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE | AT91C_US_NBSTOP_1_BIT, ulWantedBaud, configCPU_CLOCK_HZ );
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102 /* Configure the interrupt. Note the pre-emption priority is set
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103 in bits [8:15] of the priority value passed as the parameter. */
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104 IRQ_ConfigureIT( BOARD_ID_USART, ( configMAX_SYSCALL_INTERRUPT_PRIORITY << 8 ), vSerialISR );
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105 IRQ_EnableIT( BOARD_ID_USART );
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107 /* Enable receiver & transmitter. */
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108 USART_SetTransmitterEnabled( BOARD_USART_BASE, pdTRUE );
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109 USART_SetReceiverEnabled( BOARD_USART_BASE, pdTRUE );
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111 /* Configure IO for USART use. */
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112 PIO_Configure( xUSART_Pins, PIO_LISTSIZE( xUSART_Pins ) );
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114 portEXIT_CRITICAL();
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118 xReturn = ( xComPortHandle ) 0;
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121 /* This demo file only supports a single port but we have to return
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122 something to comply with the standard demo header file. */
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125 /*-----------------------------------------------------------*/
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127 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
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129 /* The port handle is not required as this driver only supports one port. */
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132 /* Get the next character from the buffer. Return false if no characters
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133 are available, or arrive before xBlockTime expires. */
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134 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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143 /*-----------------------------------------------------------*/
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145 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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147 signed char *pxNext;
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149 /* A couple of parameters that this port does not use. */
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150 ( void ) usStringLength;
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153 /* NOTE: This implementation does not handle the queue being full as no
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154 block time is used! */
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156 /* The port handle is not required as this driver only supports UART0. */
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159 /* Send each character in the string, one at a time. */
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160 pxNext = ( signed char * ) pcString;
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163 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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167 /*-----------------------------------------------------------*/
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169 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )
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171 /* Place the character in the queue of characters to be transmitted. */
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172 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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177 /* Turn on the Tx interrupt so the ISR will remove the character from the
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178 queue and send it. This does not need to be in a critical section as
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179 if the interrupt has already removed the character the next interrupt
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180 will simply turn off the Tx interrupt again. */
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185 /*-----------------------------------------------------------*/
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187 void vSerialClose( xComPortHandle xPort )
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189 /* Not supported as not required by the demo application. */
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191 /*-----------------------------------------------------------*/
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193 void vSerialISR( void )
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195 unsigned long ulStatus;
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197 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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199 /* What caused the interrupt? */
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200 ulStatus = BOARD_USART_BASE->US_CSR &= BOARD_USART_BASE->US_IMR;
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202 if( ulStatus & AT91C_US_TXRDY )
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204 /* The interrupt was caused by the THR becoming empty. Are there any
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205 more characters to transmit? */
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206 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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208 /* A character was retrieved from the queue so can be sent to the
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210 BOARD_USART_BASE->US_THR = cChar;
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214 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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219 if( ulStatus & AT91C_US_RXRDY )
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221 /* The interrupt was caused by a character being received. Grab the
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222 character from the RHR and place it in the queue or received
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224 cChar = BOARD_USART_BASE->US_RHR;
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225 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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228 /* If a task was woken by either a character being received or a character
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229 being transmitted then we may need to switch to another task. */
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230 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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