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

   1 /*\r
   2     FreeRTOS V7.5.1 - Copyright (C) 2013 Real Time Engineers Ltd.\r
   3 \r
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   5 \r
   6     ***************************************************************************\r
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  18     ***************************************************************************\r
  19 \r
  20     This file is part of the FreeRTOS distribution.\r
  21 \r
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  38     ***************************************************************************\r
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  63 */\r
  64 \r
  65 \r
  66 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR IAR AVR PORT. */\r
  67 \r
  68 \r
  69 #include <stdlib.h>\r
  70 #include "FreeRTOS.h"\r
  71 #include "queue.h"\r
  72 #include "task.h"\r
  73 #include "serial.h"\r
  74 \r
  75 #define serBAUD_DIV_CONSTANT                    ( ( unsigned long ) 16 )\r
  76 \r
  77 /* Constants for writing to UCSRB. */\r
  78 #define serRX_INT_ENABLE                                ( ( unsigned char ) 0x80 )\r
  79 #define serRX_ENABLE                                    ( ( unsigned char ) 0x10 )\r
  80 #define serTX_ENABLE                                    ( ( unsigned char ) 0x08 )\r
  81 #define serTX_INT_ENABLE                                ( ( unsigned char ) 0x20 )\r
  82 \r
  83 /* Constants for writing to UCSRC. */\r
  84 #define serUCSRC_SELECT                                 ( ( unsigned char ) 0x80 )\r
  85 #define serEIGHT_DATA_BITS                              ( ( unsigned char ) 0x06 )\r
  86 \r
  87 static xQueueHandle xRxedChars;\r
  88 static xQueueHandle xCharsForTx;\r
  89 \r
  90 #define vInterruptOn()                                                                          \\r
  91 {                                                                                                                       \\r
  92         unsigned char ucByte;                                                           \\r
  93                                                                                                                         \\r
  94         ucByte = UCSRB;                                                                                 \\r
  95         ucByte |= serTX_INT_ENABLE;                                                             \\r
  96         outb( UCSRB, ucByte );                                                                  \\r
  97 }                                                                                                                                                               \r
  98 /*-----------------------------------------------------------*/\r
  99 \r
 100 #define vInterruptOff()                                                                         \\r
 101 {                                                                                                                       \\r
 102         unsigned char ucByte;                                                           \\r
 103                                                                                                                         \\r
 104         ucByte = UCSRB;                                                                                 \\r
 105         ucByte &= ~serTX_INT_ENABLE;                                                    \\r
 106         outb( UCSRB, ucByte );                                                                  \\r
 107 }\r
 108 /*-----------------------------------------------------------*/\r
 109 \r
 110 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )\r
 111 {\r
 112 unsigned long ulBaudRateCounter;\r
 113 unsigned char ucByte;\r
 114 \r
 115         portENTER_CRITICAL();\r
 116         {\r
 117                 /* Create the queues used by the com test task. */\r
 118                 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );\r
 119                 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );\r
 120 \r
 121                 /* Calculate the baud rate register value from the equation in the\r
 122                 data sheet. */\r
 123                 ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned long ) 1;\r
 124 \r
 125                 /* Set the baud rate. */        \r
 126                 ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );      \r
 127                 outb( UBRRL, ucByte );\r
 128 \r
 129                 ulBaudRateCounter >>= ( unsigned long ) 8;\r
 130                 ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );      \r
 131                 outb( UBRRH, ucByte );\r
 132 \r
 133                 /* Enable the Rx interrupt.  The Tx interrupt will get enabled\r
 134                 later. Also enable the Rx and Tx. */\r
 135                 outb( UCSRB, serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );\r
 136 \r
 137                 /* Set the data bits to 8. */\r
 138                 outb( UCSRC, serUCSRC_SELECT | serEIGHT_DATA_BITS );\r
 139         }\r
 140         portEXIT_CRITICAL();\r
 141         \r
 142         /* Unlike other ports, this serial code does not allow for more than one\r
 143         com port.  We therefore don't return a pointer to a port structure and can\r
 144         instead just return NULL. */\r
 145         return NULL;\r
 146 }\r
 147 /*-----------------------------------------------------------*/\r
 148 \r
 149 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )\r
 150 {\r
 151         /* Get the next character from the buffer.  Return false if no characters\r
 152         are available, or arrive before xBlockTime expires. */\r
 153         if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )\r
 154         {\r
 155                 return pdTRUE;\r
 156         }\r
 157         else\r
 158         {\r
 159                 return pdFALSE;\r
 160         }\r
 161 }\r
 162 /*-----------------------------------------------------------*/\r
 163 \r
 164 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )\r
 165 {\r
 166         /* Return false if after the block time there is no room on the Tx queue. */\r
 167         if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )\r
 168         {\r
 169                 return pdFAIL;\r
 170         }\r
 171 \r
 172         vInterruptOn();\r
 173 \r
 174         return pdPASS;\r
 175 }\r
 176 /*-----------------------------------------------------------*/\r
 177 \r
 178 void vSerialClose( xComPortHandle xPort )\r
 179 {\r
 180 unsigned char ucByte;\r
 181 \r
 182         /* Turn off the interrupts.  We may also want to delete the queues and/or\r
 183         re-install the original ISR. */\r
 184 \r
 185         portENTER_CRITICAL();\r
 186         {\r
 187                 vInterruptOff();\r
 188                 ucByte = UCSRB;\r
 189                 ucByte &= ~serRX_INT_ENABLE;\r
 190                 outb( UCSRB, ucByte );\r
 191         }\r
 192         portEXIT_CRITICAL();\r
 193 }\r
 194 /*-----------------------------------------------------------*/\r
 195 \r
 196 __interrupt void SIG_UART_RECV( void )\r
 197 {\r
 198 signed char ucChar, xHigherPriorityTaskWoken = pdFALSE;\r
 199 \r
 200         /* Get the character and post it on the queue of Rxed characters.\r
 201         If the post causes a task to wake force a context switch as the woken task\r
 202         may have a higher priority than the task we have interrupted. */\r
 203         ucChar = UDR;\r
 204 \r
 205         xQueueSendFromISR( xRxedChars, &ucChar, &xHigherPriorityTaskWoken );\r
 206 \r
 207         if( xHigherPriorityTaskWoken != pdFALSE )\r
 208         {\r
 209                 taskYIELD();\r
 210         }\r
 211 }\r
 212 /*-----------------------------------------------------------*/\r
 213 \r
 214 __interrupt void SIG_UART_DATA( void )\r
 215 {\r
 216 signed char cChar, cTaskWoken = pdFALSE;\r
 217 \r
 218         if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )\r
 219         {\r
 220                 /* Send the next character queued for Tx. */\r
 221                 outb( UDR, cChar );\r
 222         }\r
 223         else\r
 224         {\r
 225                 /* Queue empty, nothing to send. */\r
 226                 vInterruptOff();\r
 227         }\r
 228 }\r
 229 \r