begriffs open source - cmsis-freertos/blob - Demo/CORTEX_STM32L152

1 /*

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67 1 tab == 4 spaces!

68 */

69

70 /*

71 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.

72

73 ***Note*** This example uses queues to send each character into an interrupt

74 service routine and out of an interrupt service routine individually. This

75 is done to demonstrate queues being used in an interrupt, and to deliberately

76 load the system to test the FreeRTOS port. It is *NOT* meant to be an

77 example of an efficient implementation. An efficient implementation should

78 use FIFO's or DMA if available, and only use FreeRTOS API functions when

79 enough has been received to warrant a task being unblocked to process the

80 data.

81 */

82

83 /* Scheduler includes. */

84 #include "FreeRTOS.h"

85 #include "queue.h"

86 #include "semphr.h"

87 #include "comtest2.h"

88

89 /* Library includes. */

90 #include "stm32l152_eval.h"

91

92 /* Demo application includes. */

93 #include "serial.h"

94 /*-----------------------------------------------------------*/

95

96 /* Misc defines. */

97 #define serINVALID_QUEUE ( ( QueueHandle_t ) 0 )

98 #define serNO_BLOCK ( ( TickType_t ) 0 )

99

100 /*-----------------------------------------------------------*/

101

102 /* The queue used to hold received characters. */

103 static QueueHandle_t xRxedChars;

104 static QueueHandle_t xCharsForTx;

105

106 /*-----------------------------------------------------------*/

107

108 /*

109 * See the serial2.h header file.

110 */

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

112 {

113 USART_InitTypeDef USART_InitStructure;

114 xComPortHandle xReturn;

115 NVIC_InitTypeDef NVIC_InitStructure;

116

117 /* Create the queues used to hold Rx/Tx characters. */

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

119 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

120

121 /* If the queues were created correctly then setup the serial port

122 hardware. */

123 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )

124 {

125 USART_InitStructure.USART_BaudRate = ulWantedBaud;

126 USART_InitStructure.USART_WordLength = USART_WordLength_8b;

127 USART_InitStructure.USART_StopBits = USART_StopBits_1;

128 USART_InitStructure.USART_Parity = USART_Parity_No;

129 USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

130 USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

131

132 /* The Eval board COM2 is being used, which in reality is the STM32

133 USART3. */

134 STM_EVAL_COMInit( COM2, &USART_InitStructure );

135

136 NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;

137 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY;

138 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; /* Not used as 4 bits are used for the pre-emption priority. */;

139 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

140 NVIC_Init( &NVIC_InitStructure );

141 USART_ITConfig( USART3, USART_IT_RXNE, ENABLE );

142 }

143 else

144 {

145 xReturn = ( xComPortHandle ) 0;

146 }

147

148 /* This demo file only supports a single port but we have to return

149 something to comply with the standard demo header file. */

150 return xReturn;

151 }

152 /*-----------------------------------------------------------*/

153

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

155 {

156 /* The port handle is not required as this driver only supports one port. */

157 ( void ) pxPort;

158

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

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

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

162 {

163 return pdTRUE;

164 }

165 else

166 {

167 return pdFALSE;

168 }

169 }

170 /*-----------------------------------------------------------*/

171

172 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )

173 {

174 signed char *pxNext;

175

176 /* A couple of parameters that this port does not use. */

177 ( void ) usStringLength;

178 ( void ) pxPort;

179

180 /* NOTE: This implementation does not handle the queue being full as no

181 block time is used! */

182

183 /* The port handle is not required as this driver only supports UART1. */

184 ( void ) pxPort;

185

186 /* Send each character in the string, one at a time. */

187 pxNext = ( signed char * ) pcString;

188 while( *pxNext )

189 {

190 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );

191 pxNext++;

192 }

193 }

194 /*-----------------------------------------------------------*/

195

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

197 {

198 signed portBASE_TYPE xReturn;

199

200 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) == pdPASS )

201 {

202 xReturn = pdPASS;

203 USART_ITConfig( USART3, USART_IT_TXE, ENABLE );

204 }

205 else

206 {

207 xReturn = pdFAIL;

208 }

209

210 return xReturn;

211 }

212 /*-----------------------------------------------------------*/

213

214 void vSerialClose( xComPortHandle xPort )

215 {

216 /* Not supported as not required by the demo application. */

217 }

218 /*-----------------------------------------------------------*/

219

220 void USART3_IRQHandler( void )

221 {

222 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

223 char cChar;

224

225 if( USART_GetITStatus( USART3, USART_IT_TXE ) == SET )

226 {

227 /* The interrupt was caused by the TX register becoming empty. Are

228 there any more characters to transmit? */

229 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )

230 {

231 /* A character was retrieved from the queue so can be sent to the

232 USART now. */

233 USART_SendData( USART3, cChar );

234 }

235 else

236 {

237 USART_ITConfig( USART3, USART_IT_TXE, DISABLE );

238 }

239 }

240

241 if( USART_GetITStatus( USART3, USART_IT_RXNE ) == SET )

242 {

243 /* A character has been received on the USART, send it to the Rx

244 handler task. */

245 cChar = USART_ReceiveData( USART3 );

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

247 }

248

249 /* If sending or receiving from a queue has caused a task to unblock, and

250 the unblocked task has a priority equal to or higher than the currently

251 running task (the task this ISR interrupted), then xHigherPriorityTaskWoken

252 will have automatically been set to pdTRUE within the queue send or receive

253 function. portEND_SWITCHING_ISR() will then ensure that this ISR returns

254 directly to the higher priority unblocked task. */

255 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );

256 }

262