1 /*This file has been prepared for Doxygen automatic documentation generation.*/
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2 /*! \file *********************************************************************
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4 * \brief FreeRTOS Serial Port management example for AVR32 UC3.
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6 * - Compiler: IAR EWAVR32 and GNU GCC for AVR32
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7 * - Supported devices: All AVR32 devices can be used.
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10 * \author Atmel Corporation: http://www.atmel.com \n
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11 * Support and FAQ: http://support.atmel.no/
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13 *****************************************************************************/
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15 /* Copyright (c) 2007, Atmel Corporation All rights reserved.
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17 * Redistribution and use in source and binary forms, with or without
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18 * modification, are permitted provided that the following conditions are met:
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20 * 1. Redistributions of source code must retain the above copyright notice,
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21 * this list of conditions and the following disclaimer.
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23 * 2. Redistributions in binary form must reproduce the above copyright notice,
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24 * this list of conditions and the following disclaimer in the documentation
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25 * and/or other materials provided with the distribution.
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27 * 3. The name of ATMEL may not be used to endorse or promote products derived
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28 * from this software without specific prior written permission.
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30 * THIS SOFTWARE IS PROVIDED BY ATMEL ``AS IS'' AND ANY EXPRESS OR IMPLIED
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31 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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32 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY AND
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33 * SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT,
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34 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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35 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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36 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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37 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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39 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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44 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR USART.
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47 /* Scheduler includes. */
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48 #include "FreeRTOS.h"
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52 /* Demo application includes. */
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54 #include <avr32/io.h>
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58 /*-----------------------------------------------------------*/
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60 /* Constants to setup and access the USART. */
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61 #define serINVALID_COMPORT_HANDLER ( ( xComPortHandle ) 0 )
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62 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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63 #define serHANDLE ( ( xComPortHandle ) 1 )
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64 #define serNO_BLOCK ( ( portTickType ) 0 )
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66 /*-----------------------------------------------------------*/
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68 /* Queues used to hold received characters, and characters waiting to be
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70 static xQueueHandle xRxedChars;
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71 static xQueueHandle xCharsForTx;
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73 /*-----------------------------------------------------------*/
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75 /* Forward declaration. */
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76 static void vprvSerialCreateQueues( unsigned portBASE_TYPE uxQueueLength,
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77 xQueueHandle *pxRxedChars,
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78 xQueueHandle *pxCharsForTx );
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80 /*-----------------------------------------------------------*/
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83 __attribute__((__noinline__))
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85 #pragma optimize = no_inline
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88 static portBASE_TYPE prvUSART_ISR_NonNakedBehaviour( void )
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90 /* Now we can declare the local variables. */
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91 signed portCHAR cChar;
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92 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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93 unsigned portLONG ulStatus;
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94 volatile avr32_usart_t *usart = serialPORT_USART;
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95 portBASE_TYPE retstatus;
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97 /* What caused the interrupt? */
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98 ulStatus = usart->csr & usart->imr;
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100 if (ulStatus & AVR32_USART_CSR_TXRDY_MASK)
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102 /* The interrupt was caused by the THR becoming empty. Are there any
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103 more characters to transmit?
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104 Because FreeRTOS is not supposed to run with nested interrupts, put all OS
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105 calls in a critical section . */
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106 portENTER_CRITICAL();
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107 retstatus = xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken );
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108 portEXIT_CRITICAL();
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110 if (retstatus == pdTRUE)
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112 /* A character was retrieved from the queue so can be sent to the
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114 usart->thr = cChar;
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118 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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119 usart->idr = AVR32_USART_IDR_TXRDY_MASK;
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123 if (ulStatus & AVR32_USART_CSR_RXRDY_MASK)
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125 /* The interrupt was caused by the receiver getting data. */
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126 cChar = usart->rhr; //TODO
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128 /* Because FreeRTOS is not supposed to run with nested interrupts, put all OS
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129 calls in a critical section . */
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130 portENTER_CRITICAL();
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131 xQueueSendFromISR(xRxedChars, &cChar, &xHigherPriorityTaskWoken);
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132 portEXIT_CRITICAL();
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135 /* The return value will be used by portEXIT_SWITCHING_ISR() to know if it
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136 should perform a vTaskSwitchContext(). */
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137 return ( xHigherPriorityTaskWoken );
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139 /*-----------------------------------------------------------*/
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142 * USART interrupt service routine.
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145 __attribute__((__naked__))
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147 #pragma shadow_registers = full // Naked.
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150 static void vUSART_ISR( void )
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152 /* This ISR can cause a context switch, so the first statement must be a
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153 call to the portENTER_SWITCHING_ISR() macro. This must be BEFORE any
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154 variable declarations. */
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155 portENTER_SWITCHING_ISR();
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157 prvUSART_ISR_NonNakedBehaviour();
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159 /* Exit the ISR. If a task was woken by either a character being received
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160 or transmitted then a context switch will occur. */
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161 portEXIT_SWITCHING_ISR();
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163 /*-----------------------------------------------------------*/
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167 * Init the serial port for the Minimal implementation.
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169 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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171 static const gpio_map_t USART_GPIO_MAP =
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173 { serialPORT_USART_RX_PIN, serialPORT_USART_RX_FUNCTION },
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174 { serialPORT_USART_TX_PIN, serialPORT_USART_TX_FUNCTION }
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177 xComPortHandle xReturn = serHANDLE;
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178 volatile avr32_usart_t *usart = serialPORT_USART;
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179 int cd; /* USART Clock Divider. */
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181 /* Create the rx and tx queues. */
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182 vprvSerialCreateQueues( uxQueueLength, &xRxedChars, &xCharsForTx );
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184 /* Configure USART. */
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185 if( ( xRxedChars != serINVALID_QUEUE ) &&
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186 ( xCharsForTx != serINVALID_QUEUE ) &&
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187 ( ulWantedBaud != ( unsigned portLONG ) 0 ) )
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189 portENTER_CRITICAL();
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194 /* Disable all USART interrupt sources to begin... */
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195 usart->idr = 0xFFFFFFFF;
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197 /* Reset mode and other registers that could cause unpredictable
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198 behaviour after reset */
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199 usart->mr = 0; /* Reset Mode register. */
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200 usart->rtor = 0; /* Reset Receiver Time-out register. */
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201 usart->ttgr = 0; /* Reset Transmitter Timeguard register. */
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203 /* Shutdown RX and TX, reset status bits, reset iterations in CSR, reset NACK
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204 and turn off DTR and RTS */
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205 usart->cr = AVR32_USART_CR_RSTRX_MASK |
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206 AVR32_USART_CR_RSTTX_MASK |
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207 AVR32_USART_CR_RXDIS_MASK |
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208 AVR32_USART_CR_TXDIS_MASK |
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209 AVR32_USART_CR_RSTSTA_MASK |
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210 AVR32_USART_CR_RSTIT_MASK |
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211 AVR32_USART_CR_RSTNACK_MASK |
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212 AVR32_USART_CR_DTRDIS_MASK |
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213 AVR32_USART_CR_RTSDIS_MASK;
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216 ** Configure USART.
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218 /* Enable USART RXD & TXD pins. */
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219 gpio_enable_module( USART_GPIO_MAP, sizeof( USART_GPIO_MAP ) / sizeof( USART_GPIO_MAP[0] ) );
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221 /* Set the USART baudrate to be as close as possible to the wanted baudrate. */
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223 * ** BAUDRATE CALCULATION **
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225 * Selected Clock Selected Clock
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226 * baudrate = ---------------- or baudrate = ----------------
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229 * (with 16x oversampling) (with 8x oversampling)
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232 if( ulWantedBaud < ( configCPU_CLOCK_HZ / 16 ) )
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234 /* Use 8x oversampling */
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235 usart->mr |= (1<<AVR32_USART_MR_OVER_OFFSET);
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236 cd = configCPU_CLOCK_HZ / (8*ulWantedBaud);
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240 return serINVALID_COMPORT_HANDLER;
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243 usart->brgr = (cd << AVR32_USART_BRGR_CD_OFFSET);
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247 /* Use 16x oversampling */
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248 usart->mr &= ~(1<<AVR32_USART_MR_OVER_OFFSET);
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249 cd = configCPU_CLOCK_HZ / (16*ulWantedBaud);
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253 /* Baudrate is too low */
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254 return serINVALID_COMPORT_HANDLER;
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258 usart->brgr = (cd << AVR32_USART_BRGR_CD_OFFSET);
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260 /* Set the USART Mode register: Mode=Normal(0), Clk selection=MCK(0),
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261 CHRL=8, SYNC=0(asynchronous), PAR=None, NBSTOP=1, CHMODE=0, MSBF=0,
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262 MODE9=0, CKLO=0, OVER(previously done when setting the baudrate),
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263 other fields not used in this mode. */
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264 usart->mr |= ((8-5) << AVR32_USART_MR_CHRL_OFFSET ) |
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265 ( 4 << AVR32_USART_MR_PAR_OFFSET ) |
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266 ( 1 << AVR32_USART_MR_NBSTOP_OFFSET);
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268 /* Write the Transmit Timeguard Register */
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272 /* Register the USART interrupt handler to the interrupt controller and
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273 enable the USART interrupt. */
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274 INTC_register_interrupt((__int_handler)&vUSART_ISR, serialPORT_USART_IRQ, INT1);
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276 /* Enable USART interrupt sources (but not Tx for now)... */
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277 usart->ier = AVR32_USART_IER_RXRDY_MASK;
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279 /* Enable receiver and transmitter... */
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280 usart->cr |= AVR32_USART_CR_TXEN_MASK | AVR32_USART_CR_RXEN_MASK;
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282 portEXIT_CRITICAL();
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286 xReturn = serINVALID_COMPORT_HANDLER;
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291 /*-----------------------------------------------------------*/
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293 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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295 /* The port handle is not required as this driver only supports UART0. */
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298 /* Get the next character from the buffer. Return false if no characters
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299 are available, or arrive before xBlockTime expires. */
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300 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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309 /*-----------------------------------------------------------*/
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311 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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313 signed portCHAR *pxNext;
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315 /* NOTE: This implementation does not handle the queue being full as no
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316 block time is used! */
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318 /* The port handle is not required as this driver only supports UART0. */
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321 /* Send each character in the string, one at a time. */
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322 pxNext = ( signed portCHAR * ) pcString;
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325 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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329 /*-----------------------------------------------------------*/
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331 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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333 volatile avr32_usart_t *usart = serialPORT_USART;
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335 /* Place the character in the queue of characters to be transmitted. */
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336 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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341 /* Turn on the Tx interrupt so the ISR will remove the character from the
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342 queue and send it. This does not need to be in a critical section as
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343 if the interrupt has already removed the character the next interrupt
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344 will simply turn off the Tx interrupt again. */
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345 usart->ier = (1 << AVR32_USART_IER_TXRDY_OFFSET);
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349 /*-----------------------------------------------------------*/
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351 void vSerialClose( xComPortHandle xPort )
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353 /* Not supported as not required by the demo application. */
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355 /*-----------------------------------------------------------*/
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357 /*###########################################################*/
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360 * Create the rx and tx queues.
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362 static void vprvSerialCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx )
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364 /* Create the queues used to hold Rx and Tx characters. */
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365 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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366 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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368 /* Pass back a reference to the queues so the serial API file can
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369 post/receive characters. */
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370 *pxRxedChars = xRxedChars;
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371 *pxCharsForTx = xCharsForTx;
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373 /*-----------------------------------------------------------*/
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