git.sur5r.net Git - freertos/blob - FreeRTOS/Demo/AVR_ATMega323_IAR/serial/serial.c

   1 /*\r
   2     FreeRTOS V8.1.0 - Copyright (C) 2014 Real Time Engineers Ltd. \r
   3     All rights reserved\r
   4 \r
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   7     ***************************************************************************\r
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  19     ***************************************************************************\r
  20 \r
  21     This file is part of the FreeRTOS distribution.\r
  22 \r
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  35     link: http://www.freertos.org/a00114.html\r
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  39     ***************************************************************************\r
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  64 */\r
  65 \r
  66 \r
  67 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR IAR AVR PORT. */\r
  68 \r
  69 \r
  70 #include <stdlib.h>\r
  71 #include "FreeRTOS.h"\r
  72 #include "queue.h"\r
  73 #include "task.h"\r
  74 #include "serial.h"\r
  75 \r
  76 #define serBAUD_DIV_CONSTANT                    ( ( unsigned long ) 16 )\r
  77 \r
  78 /* Constants for writing to UCSRB. */\r
  79 #define serRX_INT_ENABLE                                ( ( unsigned char ) 0x80 )\r
  80 #define serRX_ENABLE                                    ( ( unsigned char ) 0x10 )\r
  81 #define serTX_ENABLE                                    ( ( unsigned char ) 0x08 )\r
  82 #define serTX_INT_ENABLE                                ( ( unsigned char ) 0x20 )\r
  83 \r
  84 /* Constants for writing to UCSRC. */\r
  85 #define serUCSRC_SELECT                                 ( ( unsigned char ) 0x80 )\r
  86 #define serEIGHT_DATA_BITS                              ( ( unsigned char ) 0x06 )\r
  87 \r
  88 static QueueHandle_t xRxedChars;\r
  89 static QueueHandle_t xCharsForTx;\r
  90 \r
  91 #define vInterruptOn()                                                                          \\r
  92 {                                                                                                                       \\r
  93         unsigned char ucByte;                                                           \\r
  94                                                                                                                         \\r
  95         ucByte = UCSRB;                                                                                 \\r
  96         ucByte |= serTX_INT_ENABLE;                                                             \\r
  97         outb( UCSRB, ucByte );                                                                  \\r
  98 }                                                                                                                                                               \r
  99 /*-----------------------------------------------------------*/\r
 100 \r
 101 #define vInterruptOff()                                                                         \\r
 102 {                                                                                                                       \\r
 103         unsigned char ucByte;                                                           \\r
 104                                                                                                                         \\r
 105         ucByte = UCSRB;                                                                                 \\r
 106         ucByte &= ~serTX_INT_ENABLE;                                                    \\r
 107         outb( UCSRB, ucByte );                                                                  \\r
 108 }\r
 109 /*-----------------------------------------------------------*/\r
 110 \r
 111 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )\r
 112 {\r
 113 unsigned long ulBaudRateCounter;\r
 114 unsigned char ucByte;\r
 115 \r
 116         portENTER_CRITICAL();\r
 117         {\r
 118                 /* Create the queues used by the com test task. */\r
 119                 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );\r
 120                 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );\r
 121 \r
 122                 /* Calculate the baud rate register value from the equation in the\r
 123                 data sheet. */\r
 124                 ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned long ) 1;\r
 125 \r
 126                 /* Set the baud rate. */        \r
 127                 ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );      \r
 128                 outb( UBRRL, ucByte );\r
 129 \r
 130                 ulBaudRateCounter >>= ( unsigned long ) 8;\r
 131                 ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );      \r
 132                 outb( UBRRH, ucByte );\r
 133 \r
 134                 /* Enable the Rx interrupt.  The Tx interrupt will get enabled\r
 135                 later. Also enable the Rx and Tx. */\r
 136                 outb( UCSRB, serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );\r
 137 \r
 138                 /* Set the data bits to 8. */\r
 139                 outb( UCSRC, serUCSRC_SELECT | serEIGHT_DATA_BITS );\r
 140         }\r
 141         portEXIT_CRITICAL();\r
 142         \r
 143         /* Unlike other ports, this serial code does not allow for more than one\r
 144         com port.  We therefore don't return a pointer to a port structure and can\r
 145         instead just return NULL. */\r
 146         return NULL;\r
 147 }\r
 148 /*-----------------------------------------------------------*/\r
 149 \r
 150 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )\r
 151 {\r
 152         /* Get the next character from the buffer.  Return false if no characters\r
 153         are available, or arrive before xBlockTime expires. */\r
 154         if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )\r
 155         {\r
 156                 return pdTRUE;\r
 157         }\r
 158         else\r
 159         {\r
 160                 return pdFALSE;\r
 161         }\r
 162 }\r
 163 /*-----------------------------------------------------------*/\r
 164 \r
 165 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )\r
 166 {\r
 167         /* Return false if after the block time there is no room on the Tx queue. */\r
 168         if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )\r
 169         {\r
 170                 return pdFAIL;\r
 171         }\r
 172 \r
 173         vInterruptOn();\r
 174 \r
 175         return pdPASS;\r
 176 }\r
 177 /*-----------------------------------------------------------*/\r
 178 \r
 179 void vSerialClose( xComPortHandle xPort )\r
 180 {\r
 181 unsigned char ucByte;\r
 182 \r
 183         /* Turn off the interrupts.  We may also want to delete the queues and/or\r
 184         re-install the original ISR. */\r
 185 \r
 186         portENTER_CRITICAL();\r
 187         {\r
 188                 vInterruptOff();\r
 189                 ucByte = UCSRB;\r
 190                 ucByte &= ~serRX_INT_ENABLE;\r
 191                 outb( UCSRB, ucByte );\r
 192         }\r
 193         portEXIT_CRITICAL();\r
 194 }\r
 195 /*-----------------------------------------------------------*/\r
 196 \r
 197 __interrupt void SIG_UART_RECV( void )\r
 198 {\r
 199 signed char ucChar, xHigherPriorityTaskWoken = pdFALSE;\r
 200 \r
 201         /* Get the character and post it on the queue of Rxed characters.\r
 202         If the post causes a task to wake force a context switch as the woken task\r
 203         may have a higher priority than the task we have interrupted. */\r
 204         ucChar = UDR;\r
 205 \r
 206         xQueueSendFromISR( xRxedChars, &ucChar, &xHigherPriorityTaskWoken );\r
 207 \r
 208         if( xHigherPriorityTaskWoken != pdFALSE )\r
 209         {\r
 210                 taskYIELD();\r
 211         }\r
 212 }\r
 213 /*-----------------------------------------------------------*/\r
 214 \r
 215 __interrupt void SIG_UART_DATA( void )\r
 216 {\r
 217 signed char cChar, cTaskWoken = pdFALSE;\r
 218 \r
 219         if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )\r
 220         {\r
 221                 /* Send the next character queued for Tx. */\r
 222                 outb( UDR, cChar );\r
 223         }\r
 224         else\r
 225         {\r
 226                 /* Queue empty, nothing to send. */\r
 227                 vInterruptOff();\r
 228         }\r
 229 }\r
 230 \r