begriffs open source - cmsis-freertos/blob - Demo/AVR_ATMega323

1 /*

4

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10 the terms of the GNU General Public License (version 2) as published by the

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13 ***************************************************************************

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16 >>! obliged to provide the source code for proprietary components !<<

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18 ***************************************************************************

19

20 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY

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22 FOR A PARTICULAR PURPOSE. Full license text is available on the following

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25 ***************************************************************************

26 * *

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65 mission critical applications that require provable dependability.

66

67 1 tab == 4 spaces!

68 */

69

70 /*

71 Changes from V1.2.3

72

73 + The function xPortInitMinimal() has been renamed to

74 xSerialPortInitMinimal() and the function xPortInit() has been renamed

75 to xSerialPortInit().

76

77 Changes from V2.0.0

78

79 + Delay periods are now specified using variables and constants of

80 TickType_t rather than unsigned long.

81 + xQueueReceiveFromISR() used in place of xQueueReceive() within the ISR.

82

83 Changes from V2.6.0

84

85 + Replaced the inb() and outb() functions with direct memory

86 access. This allows the port to be built with the 20050414 build of

87 WinAVR.

88 */

89

90 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */

91

92

93 #include <stdlib.h>

94 #include <avr/interrupt.h>

95 #include "FreeRTOS.h"

96 #include "queue.h"

97 #include "task.h"

98 #include "serial.h"

99

100 #define serBAUD_DIV_CONSTANT ( ( unsigned long ) 16 )

101

102 /* Constants for writing to UCSRB. */

103 #define serRX_INT_ENABLE ( ( unsigned char ) 0x80 )

104 #define serRX_ENABLE ( ( unsigned char ) 0x10 )

105 #define serTX_ENABLE ( ( unsigned char ) 0x08 )

106 #define serTX_INT_ENABLE ( ( unsigned char ) 0x20 )

107

108 /* Constants for writing to UCSRC. */

109 #define serUCSRC_SELECT ( ( unsigned char ) 0x80 )

110 #define serEIGHT_DATA_BITS ( ( unsigned char ) 0x06 )

111

112 static QueueHandle_t xRxedChars;

113 static QueueHandle_t xCharsForTx;

114

115 #define vInterruptOn() \

116 { \

117 unsigned char ucByte; \

118 \

119 ucByte = UCSRB; \

120 ucByte |= serTX_INT_ENABLE; \

121 UCSRB = ucByte; \

122 }

123 /*-----------------------------------------------------------*/

124

125 #define vInterruptOff() \

126 { \

127 unsigned char ucInByte; \

128 \

129 ucInByte = UCSRB; \

130 ucInByte &= ~serTX_INT_ENABLE; \

131 UCSRB = ucInByte; \

132 }

133 /*-----------------------------------------------------------*/

134

135 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )

136 {

137 unsigned long ulBaudRateCounter;

138 unsigned char ucByte;

139

140 portENTER_CRITICAL();

141 {

142 /* Create the queues used by the com test task. */

143 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

144 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

145

146 /* Calculate the baud rate register value from the equation in the

147 data sheet. */

148 ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned long ) 1;

149

150 /* Set the baud rate. */

151 ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );

152 UBRRL = ucByte;

153

154 ulBaudRateCounter >>= ( unsigned long ) 8;

155 ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );

156 UBRRH = ucByte;

157

158 /* Enable the Rx interrupt. The Tx interrupt will get enabled

159 later. Also enable the Rx and Tx. */

160 UCSRB = ( serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );

161

162 /* Set the data bits to 8. */

163 UCSRC = ( serUCSRC_SELECT | serEIGHT_DATA_BITS );

164 }

165 portEXIT_CRITICAL();

166

167 /* Unlike other ports, this serial code does not allow for more than one

168 com port. We therefore don't return a pointer to a port structure and can

169 instead just return NULL. */

170 return NULL;

171 }

172 /*-----------------------------------------------------------*/

173

174 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )

175 {

176 /* Only one port is supported. */

177 ( void ) pxPort;

178

179 /* Get the next character from the buffer. Return false if no characters

180 are available, or arrive before xBlockTime expires. */

181 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )

182 {

183 return pdTRUE;

184 }

185 else

186 {

187 return pdFALSE;

188 }

189 }

190 /*-----------------------------------------------------------*/

191

192 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )

193 {

194 /* Only one port is supported. */

195 ( void ) pxPort;

196

197 /* Return false if after the block time there is no room on the Tx queue. */

198 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )

199 {

200 return pdFAIL;

201 }

202

203 vInterruptOn();

204

205 return pdPASS;

206 }

207 /*-----------------------------------------------------------*/

208

209 void vSerialClose( xComPortHandle xPort )

210 {

211 unsigned char ucByte;

212

213 /* The parameter is not used. */

214 ( void ) xPort;

215

216 /* Turn off the interrupts. We may also want to delete the queues and/or

217 re-install the original ISR. */

218

219 portENTER_CRITICAL();

220 {

221 vInterruptOff();

222 ucByte = UCSRB;

223 ucByte &= ~serRX_INT_ENABLE;

224 UCSRB = ucByte;

225 }

226 portEXIT_CRITICAL();

227 }

228 /*-----------------------------------------------------------*/

229

230 SIGNAL( SIG_UART_RECV )

231 {

232 signed char cChar;

233 signed portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

234

235 /* Get the character and post it on the queue of Rxed characters.

236 If the post causes a task to wake force a context switch as the woken task

237 may have a higher priority than the task we have interrupted. */

238 cChar = UDR;

239

240 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );

241

242 if( xHigherPriorityTaskWoken != pdFALSE )

243 {

244 taskYIELD();

245 }

246 }

247 /*-----------------------------------------------------------*/

248

249 SIGNAL( SIG_UART_DATA )

250 {

251 signed char cChar, cTaskWoken;

252

253 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )

254 {

255 /* Send the next character queued for Tx. */

256 UDR = cChar;

257 }

258 else

259 {

260 /* Queue empty, nothing to send. */

261 vInterruptOff();

262 }

263 }

264