2 FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry.
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14 GNU General Public License for more details.
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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27 ***************************************************************************
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29 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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31 * This is a concise, step by step, 'hands on' guide that describes both *
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32 * general multitasking concepts and FreeRTOS specifics. It presents and *
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33 * explains numerous examples that are written using the FreeRTOS API. *
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34 * Full source code for all the examples is provided in an accompanying *
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37 ***************************************************************************
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38 ***************************************************************************
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40 Please ensure to read the configuration and relevant port sections of the
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41 online documentation.
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43 http://www.FreeRTOS.org - Documentation, latest information, license and
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46 http://www.SafeRTOS.com - A version that is certified for use in safety
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49 http://www.OpenRTOS.com - Commercial support, development, porting,
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50 licensing and training services.
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55 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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58 /* Standard includes. */
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61 /* Scheduler includes. */
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62 #include "FreeRTOS.h"
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66 /* Demo application includes. */
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69 /*-----------------------------------------------------------*/
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71 /* Constants to setup and access the UART. */
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72 #define serDLAB ( ( unsigned portCHAR ) 0x80 )
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73 #define serENABLE_INTERRUPTS ( ( unsigned portCHAR ) 0x03 )
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74 #define serNO_PARITY ( ( unsigned portCHAR ) 0x00 )
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75 #define ser1_STOP_BIT ( ( unsigned portCHAR ) 0x00 )
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76 #define ser8_BIT_CHARS ( ( unsigned portCHAR ) 0x03 )
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77 #define serFIFO_ON ( ( unsigned portCHAR ) 0x01 )
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78 #define serCLEAR_FIFO ( ( unsigned portCHAR ) 0x06 )
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79 #define serWANTED_CLOCK_SCALING ( ( unsigned portLONG ) 16 )
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81 /* Constants to setup and access the VIC. */
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82 #define serU0VIC_CHANNEL ( ( unsigned portLONG ) 0x0006 )
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83 #define serU0VIC_CHANNEL_BIT ( ( unsigned portLONG ) 0x0040 )
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84 #define serU0VIC_ENABLE ( ( unsigned portLONG ) 0x0020 )
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85 #define serCLEAR_VIC_INTERRUPT ( ( unsigned portLONG ) 0 )
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87 /* Constants to determine the ISR source. */
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88 #define serSOURCE_THRE ( ( unsigned portCHAR ) 0x02 )
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89 #define serSOURCE_RX_TIMEOUT ( ( unsigned portCHAR ) 0x0c )
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90 #define serSOURCE_ERROR ( ( unsigned portCHAR ) 0x06 )
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91 #define serSOURCE_RX ( ( unsigned portCHAR ) 0x04 )
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92 #define serINTERRUPT_SOURCE_MASK ( ( unsigned portCHAR ) 0x0f )
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95 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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96 #define serHANDLE ( ( xComPortHandle ) 1 )
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97 #define serNO_BLOCK ( ( portTickType ) 0 )
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99 /*-----------------------------------------------------------*/
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101 /* Queues used to hold received characters, and characters waiting to be
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103 static xQueueHandle xRxedChars;
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104 static xQueueHandle xCharsForTx;
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105 static volatile portLONG lTHREEmpty = pdFALSE;
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107 /*-----------------------------------------------------------*/
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109 /* The ISR. Note that this is called by a wrapper written in the file
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110 SerialISR.s79. See the WEB documentation for this port for further
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112 __arm void vSerialISR( void );
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114 /*-----------------------------------------------------------*/
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116 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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118 unsigned portLONG ulDivisor, ulWantedClock;
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119 xComPortHandle xReturn = serHANDLE;
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120 extern void ( vSerialISREntry) ( void );
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122 /* Create the queues used to hold Rx and Tx characters. */
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123 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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124 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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126 /* Initialise the THRE empty flag. */
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127 lTHREEmpty = pdTRUE;
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130 ( xRxedChars != serINVALID_QUEUE ) &&
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131 ( xCharsForTx != serINVALID_QUEUE ) &&
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132 ( ulWantedBaud != ( unsigned portLONG ) 0 )
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135 portENTER_CRITICAL();
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137 /* Setup the baud rate: Calculate the divisor value. */
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138 ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING;
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139 ulDivisor = configCPU_CLOCK_HZ / ulWantedClock;
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141 /* Set the DLAB bit so we can access the divisor. */
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144 /* Setup the divisor. */
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145 U0DLL = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
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147 U0DLM = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
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149 /* Turn on the FIFO's and clear the buffers. */
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150 U0FCR = ( serFIFO_ON | serCLEAR_FIFO );
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152 /* Setup transmission format. */
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153 U0LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS;
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155 /* Setup the VIC for the UART. */
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156 VICIntSelect &= ~( serU0VIC_CHANNEL_BIT );
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157 VICIntEnable |= serU0VIC_CHANNEL_BIT;
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158 VICVectAddr1 = ( unsigned portLONG ) vSerialISREntry;
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159 VICVectCntl1 = serU0VIC_CHANNEL | serU0VIC_ENABLE;
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161 /* Enable UART0 interrupts. */
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162 U0IER |= serENABLE_INTERRUPTS;
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164 portEXIT_CRITICAL();
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166 xReturn = ( xComPortHandle ) 1;
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170 xReturn = ( xComPortHandle ) 0;
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175 /*-----------------------------------------------------------*/
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177 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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179 /* The port handle is not required as this driver only supports UART0. */
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182 /* Get the next character from the buffer. Return false if no characters
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183 are available, or arrive before xBlockTime expires. */
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184 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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193 /*-----------------------------------------------------------*/
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195 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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197 signed portCHAR *pxNext;
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199 /* NOTE: This implementation does not handle the queue being full as no
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200 block time is used! */
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202 /* The port handle is not required as this driver only supports UART0. */
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204 ( void ) usStringLength;
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206 /* Send each character in the string, one at a time. */
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207 pxNext = ( signed portCHAR * ) pcString;
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210 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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214 /*-----------------------------------------------------------*/
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216 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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218 signed portBASE_TYPE xReturn;
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220 /* The port handle is not required as this driver only supports UART0. */
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223 portENTER_CRITICAL();
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225 /* Is there space to write directly to the UART? */
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226 if( lTHREEmpty == ( portLONG ) pdTRUE )
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228 /* We wrote the character directly to the UART, so was
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230 lTHREEmpty = pdFALSE;
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236 /* We cannot write directly to the UART, so queue the character.
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237 Block for a maximum of xBlockTime if there is no space in the
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238 queue. It is ok to block within a critical section as each
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239 task has it's own critical section management. */
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240 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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242 /* Depending on queue sizing and task prioritisation: While we
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243 were blocked waiting to post interrupts were not disabled. It is
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244 possible that the serial ISR has emptied the Tx queue, in which
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245 case we need to start the Tx off again. */
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246 if( lTHREEmpty == ( portLONG ) pdTRUE )
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248 xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
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249 lTHREEmpty = pdFALSE;
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254 portEXIT_CRITICAL();
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258 /*-----------------------------------------------------------*/
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260 __arm void vSerialISR( void )
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262 signed portCHAR cChar;
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263 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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265 /* What caused the interrupt? */
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266 switch( U0IIR & serINTERRUPT_SOURCE_MASK )
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268 case serSOURCE_ERROR : /* Not handling this, but clear the interrupt. */
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272 case serSOURCE_THRE : /* The THRE is empty. If there is another
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273 character in the Tx queue, send it now. */
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274 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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280 /* There are no further characters
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281 queued to send so we can indicate
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282 that the THRE is available. */
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283 lTHREEmpty = pdTRUE;
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287 case serSOURCE_RX_TIMEOUT :
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288 case serSOURCE_RX : /* A character was received. Place it in
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289 the queue of received characters. */
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291 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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294 default : /* There is nothing to do, leave the ISR. */
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298 /* Exit the ISR. If a task was woken by either a character being received
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299 or transmitted then a context switch will occur. */
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300 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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302 /* Clear the ISR in the VIC. */
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303 VICVectAddr = serCLEAR_VIC_INTERRUPT;
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305 /*-----------------------------------------------------------*/
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