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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31 *NOTE* - This file is designed to test some of the RTOS features - it is
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32 not intended to represent an efficient implementation!
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35 /* Standard includes. */
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38 /* Scheduler includes. */
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39 #include "FreeRTOS.h"
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42 /* Demo application includes. */
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46 /* Hardware specifics. */
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47 #define serRX_DATA_PIN ( 0x01 )
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48 #define serTX_DATA_PIN ( 0x02 )
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49 #define serCLOCK_Fxx_DIV_8 0x03
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50 #define serUPWR ( 0x80 )
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51 #define serUTXE ( 0x40 )
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52 #define serURXE ( 0x20 )
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53 #define serUCL ( 0x02 )
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54 #define serLSB ( 0x10 )
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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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61 /*-----------------------------------------------------------*/
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63 /* Queues used to hold received characters, and characters waiting to be
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65 static QueueHandle_t xRxedChars;
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66 static QueueHandle_t xCharsForTx;
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68 /*-----------------------------------------------------------*/
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70 /* Interrupt entry point written in the assembler file serialISR.s85. */
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71 extern void vSerialISREntry( void );
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73 /* Flag to indicate whether or not there are characters already queued to send. */
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74 static volatile unsigned long ulTxInProgress = pdFALSE;
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76 /*-----------------------------------------------------------*/
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79 * See the serial2.h header file.
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81 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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83 xComPortHandle xReturn = serHANDLE;
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84 const unsigned long ulFuclk = ( configCPU_CLOCK_HZ / 2 ) / 8UL;
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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 /* Set the UART0 Rx and Tx pins to their alternative function. */
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97 PMC3 |= ( serRX_DATA_PIN | serTX_DATA_PIN );
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98 PM3 &= ~( serTX_DATA_PIN );
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100 /* Setup clock for required baud. */
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101 UD0CTL1 = serCLOCK_Fxx_DIV_8;
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102 UD0CTL2 = ulFuclk / ( 2 * ulWantedBaud );
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104 /* Enable, n81. */
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105 UD0CTL0 = ( serUPWR | serUTXE | serURXE | serUCL | serLSB );
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107 /* Enable interrupts for both Rx and Tx. */
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111 ulTxInProgress = pdFALSE;
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113 portEXIT_CRITICAL();
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117 xReturn = ( xComPortHandle ) 0;
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120 /* This demo file only supports a single port but we have to return
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121 something to comply with the standard demo header file. */
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124 /*-----------------------------------------------------------*/
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126 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
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128 /* The port handle is not required as this driver only supports one port. */
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131 /* Get the next character from the buffer. Return false if no characters
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132 are available, or arrive before xBlockTime expires. */
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133 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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142 /*-----------------------------------------------------------*/
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144 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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146 signed char *pxNext;
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148 /* A couple of parameters that this port does not use. */
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149 ( void ) usStringLength;
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152 /* NOTE: This implementation does not handle the queue being full as no
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153 block time is used! */
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155 /* The port handle is not required as this driver only supports UART0. */
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158 /* Send each character in the string, one at a time. */
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159 pxNext = ( signed char * ) pcString;
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162 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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166 /*-----------------------------------------------------------*/
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168 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )
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170 portBASE_TYPE xReturn = pdPASS;
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172 portENTER_CRITICAL();
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174 /* There are currently no characters queued up to send so write the
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175 character directly to the UART. */
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176 if( ulTxInProgress == pdFALSE )
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179 ulTxInProgress = pdTRUE;
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183 /* The UART is already busy so write the character to the Tx queue.
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184 The queue is drained from within the Tx interrupt. */
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185 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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191 portEXIT_CRITICAL();
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195 /*-----------------------------------------------------------*/
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197 void vSerialClose( xComPortHandle xPort )
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199 /* Not supported as not required by the demo application. */
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201 /*-----------------------------------------------------------*/
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203 /* Tx interrupt handler. This is called from the asm file wrapper. */
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204 void vUARTTxISRHandler( void )
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207 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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209 /* Are there any more characters queue to transmit? */
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210 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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212 /* Send the next character. */
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217 /* The UART is no longer active. */
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218 ulTxInProgress = pdFALSE;
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221 /* If reading a character from the Rx queue caused a task to unblock, and
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222 the unblocked task has a priority higher than the currently running task,
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223 then xHigherPriorityTaskWoken will have been set to true and a context
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224 switch should occur now. */
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225 portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
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227 /*-----------------------------------------------------------*/
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229 /* Rx interrupt handler. This is called from the asm file wrapper. */
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230 void vUARTRxISRHandler( void )
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233 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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235 /* Send the received character to the Rx queue. */
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237 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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239 /* If sending a character to the Tx queue caused a task to unblock, and
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240 the unblocked task has a priority higher than the currently running task,
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241 then xHigherPriorityTaskWoken will have been set to true and a context
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242 switch should occur now. */
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243 portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
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