2 FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.
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4 This file is part of the FreeRTOS distribution.
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6 FreeRTOS is free software; you can redistribute it and/or modify it under
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7 the terms of the GNU General Public License (version 2) as published by the
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8 Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS without being obliged to provide the
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11 source code for proprietary components outside of the FreeRTOS kernel.
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12 Alternative commercial license and support terms are also available upon
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13 request. See the licensing section of http://www.FreeRTOS.org for full
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16 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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18 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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21 You should have received a copy of the GNU General Public License along
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22 with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
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23 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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26 ***************************************************************************
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28 * The FreeRTOS eBook and reference manual are available to purchase for a *
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29 * small fee. Help yourself get started quickly while also helping the *
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30 * FreeRTOS project! See http://www.FreeRTOS.org/Documentation for details *
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32 ***************************************************************************
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36 Please ensure to read the configuration and relevant port sections of the
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37 online documentation.
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39 http://www.FreeRTOS.org - Documentation, latest information, license and
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42 http://www.SafeRTOS.com - A version that is certified for use in safety
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45 http://www.OpenRTOS.com - Commercial support, development, porting,
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46 licensing and training services.
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52 + Made serial ISR handling more complete and robust.
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56 + Split serial.c into serial.c and serialISR.c. serial.c can be
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57 compiled using ARM or THUMB modes. serialISR.c must always be
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58 compiled in ARM mode.
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59 + Another small change to cSerialPutChar().
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63 + In cSerialPutChar() an extra check is made to ensure the post to
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64 the queue was successful if then attempting to retrieve the posted
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70 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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72 This file contains all the serial port components that can be compiled to
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73 either ARM or THUMB mode. Components that must be compiled to ARM mode are
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74 contained in serialISR.c.
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77 /* Standard includes. */
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80 /* Scheduler includes. */
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81 #include "FreeRTOS.h"
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85 /* Demo application includes. */
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88 /*-----------------------------------------------------------*/
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90 /* Constants to setup and access the UART. */
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91 #define serDLAB ( ( unsigned char ) 0x80 )
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92 #define serENABLE_INTERRUPTS ( ( unsigned char ) 0x03 )
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93 #define serNO_PARITY ( ( unsigned char ) 0x00 )
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94 #define ser1_STOP_BIT ( ( unsigned char ) 0x00 )
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95 #define ser8_BIT_CHARS ( ( unsigned char ) 0x03 )
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96 #define serFIFO_ON ( ( unsigned char ) 0x01 )
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97 #define serCLEAR_FIFO ( ( unsigned char ) 0x06 )
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98 #define serWANTED_CLOCK_SCALING ( ( unsigned long ) 16 )
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100 /* Constants to setup and access the VIC. */
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101 #define serUART0_VIC_CHANNEL ( ( unsigned long ) 0x0006 )
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102 #define serUART0_VIC_CHANNEL_BIT ( ( unsigned long ) 0x0040 )
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103 #define serUART0_VIC_ENABLE ( ( unsigned long ) 0x0020 )
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104 #define serCLEAR_VIC_INTERRUPT ( ( unsigned long ) 0 )
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106 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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107 #define serHANDLE ( ( xComPortHandle ) 1 )
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108 #define serNO_BLOCK ( ( portTickType ) 0 )
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110 /*-----------------------------------------------------------*/
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112 /* Queues used to hold received characters, and characters waiting to be
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114 static xQueueHandle xRxedChars;
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115 static xQueueHandle xCharsForTx;
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117 /*-----------------------------------------------------------*/
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119 /* Communication flag between the interrupt service routine and serial API. */
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120 static volatile long *plTHREEmpty;
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123 * The queues are created in serialISR.c as they are used from the ISR.
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124 * Obtain references to the queues and THRE Empty flag.
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126 extern void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx, long volatile **pplTHREEmptyFlag );
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128 /*-----------------------------------------------------------*/
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130 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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132 unsigned long ulDivisor, ulWantedClock;
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133 xComPortHandle xReturn = serHANDLE;
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134 extern void ( vUART_ISR_Wrapper )( void );
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136 /* The queues are used in the serial ISR routine, so are created from
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137 serialISR.c (which is always compiled to ARM mode. */
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138 vSerialISRCreateQueues( uxQueueLength, &xRxedChars, &xCharsForTx, &plTHREEmpty );
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141 ( xRxedChars != serINVALID_QUEUE ) &&
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142 ( xCharsForTx != serINVALID_QUEUE ) &&
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143 ( ulWantedBaud != ( unsigned long ) 0 )
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146 portENTER_CRITICAL();
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148 /* Setup the baud rate: Calculate the divisor value. */
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149 ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING;
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150 ulDivisor = configCPU_CLOCK_HZ / ulWantedClock;
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152 /* Set the DLAB bit so we can access the divisor. */
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153 UART0_LCR |= serDLAB;
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155 /* Setup the divisor. */
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156 UART0_DLL = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff );
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158 UART0_DLM = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff );
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160 /* Turn on the FIFO's and clear the buffers. */
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161 UART0_FCR = ( serFIFO_ON | serCLEAR_FIFO );
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163 /* Setup transmission format. */
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164 UART0_LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS;
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166 /* Setup the VIC for the UART. */
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167 VICIntSelect &= ~( serUART0_VIC_CHANNEL_BIT );
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168 VICIntEnable |= serUART0_VIC_CHANNEL_BIT;
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169 VICVectAddr1 = ( long ) vUART_ISR_Wrapper;
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170 VICVectCntl1 = serUART0_VIC_CHANNEL | serUART0_VIC_ENABLE;
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172 /* Enable UART0 interrupts. */
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173 UART0_IER |= serENABLE_INTERRUPTS;
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175 portEXIT_CRITICAL();
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179 xReturn = ( xComPortHandle ) 0;
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184 /*-----------------------------------------------------------*/
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186 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
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188 /* The port handle is not required as this driver only supports UART0. */
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191 /* Get the next character from the buffer. Return false if no characters
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192 are available, or arrive before xBlockTime expires. */
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193 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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202 /*-----------------------------------------------------------*/
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204 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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206 signed char *pxNext;
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208 /* NOTE: This implementation does not handle the queue being full as no
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209 block time is used! */
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211 /* The port handle is not required as this driver only supports UART0. */
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213 ( void ) usStringLength;
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215 /* Send each character in the string, one at a time. */
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216 pxNext = ( signed char * ) pcString;
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219 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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223 /*-----------------------------------------------------------*/
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225 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
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227 signed portBASE_TYPE xReturn;
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229 /* This demo driver only supports one port so the parameter is not used. */
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232 portENTER_CRITICAL();
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234 /* Is there space to write directly to the UART? */
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235 if( *plTHREEmpty == ( long ) pdTRUE )
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237 /* We wrote the character directly to the UART, so was
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239 *plTHREEmpty = pdFALSE;
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240 UART0_THR = cOutChar;
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245 /* We cannot write directly to the UART, so queue the character.
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246 Block for a maximum of xBlockTime if there is no space in the
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248 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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250 /* Depending on queue sizing and task prioritisation: While we
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251 were blocked waiting to post interrupts were not disabled. It is
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252 possible that the serial ISR has emptied the Tx queue, in which
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253 case we need to start the Tx off again. */
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254 if( ( *plTHREEmpty == ( long ) pdTRUE ) && ( xReturn == pdPASS ) )
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256 xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
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257 *plTHREEmpty = pdFALSE;
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258 UART0_THR = cOutChar;
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262 portEXIT_CRITICAL();
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266 /*-----------------------------------------------------------*/
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268 void vSerialClose( xComPortHandle xPort )
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270 /* Not supported as not required by the demo application. */
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273 /*-----------------------------------------------------------*/
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