1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
|
/*
FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FreeRTOS.org is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FreeRTOS.org; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
***************************************************************************
* *
* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
* *
* This is a concise, step by step, 'hands on' guide that describes both *
* general multitasking concepts and FreeRTOS specifics. It presents and *
* explains numerous examples that are written using the FreeRTOS API. *
* Full source code for all the examples is provided in an accompanying *
* .zip file. *
* *
***************************************************************************
***************************************************************************
Please ensure to read the configuration and relevant port sections of the
online documentation.
http://www.FreeRTOS.org - Documentation, latest information, license and
contact details.
http://www.SafeRTOS.com - A version that is certified for use in safety
critical systems.
http://www.OpenRTOS.com - Commercial support, development, porting,
licensing and training services.
*/
/*
BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
*/
/* Standard includes. */
#include <stdlib.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
/* Demo application includes. */
#include "serial.h"
/*-----------------------------------------------------------*/
/* Constants to setup and access the UART. */
#define serDLAB ( ( unsigned portCHAR ) 0x80 )
#define serENABLE_INTERRUPTS ( ( unsigned portCHAR ) 0x03 )
#define serNO_PARITY ( ( unsigned portCHAR ) 0x00 )
#define ser1_STOP_BIT ( ( unsigned portCHAR ) 0x00 )
#define ser8_BIT_CHARS ( ( unsigned portCHAR ) 0x03 )
#define serFIFO_ON ( ( unsigned portCHAR ) 0x01 )
#define serCLEAR_FIFO ( ( unsigned portCHAR ) 0x06 )
#define serWANTED_CLOCK_SCALING ( ( unsigned portLONG ) 16 )
/* Constants to setup and access the VIC. */
#define serU0VIC_CHANNEL ( ( unsigned portLONG ) 0x0006 )
#define serU0VIC_CHANNEL_BIT ( ( unsigned portLONG ) 0x0040 )
#define serU0VIC_ENABLE ( ( unsigned portLONG ) 0x0020 )
#define serCLEAR_VIC_INTERRUPT ( ( unsigned portLONG ) 0 )
/* Constants to determine the ISR source. */
#define serSOURCE_THRE ( ( unsigned portCHAR ) 0x02 )
#define serSOURCE_RX_TIMEOUT ( ( unsigned portCHAR ) 0x0c )
#define serSOURCE_ERROR ( ( unsigned portCHAR ) 0x06 )
#define serSOURCE_RX ( ( unsigned portCHAR ) 0x04 )
#define serINTERRUPT_SOURCE_MASK ( ( unsigned portCHAR ) 0x0f )
/* Misc. */
#define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
#define serHANDLE ( ( xComPortHandle ) 1 )
#define serNO_BLOCK ( ( portTickType ) 0 )
/*-----------------------------------------------------------*/
/* Queues used to hold received characters, and characters waiting to be
transmitted. */
static xQueueHandle xRxedChars;
static xQueueHandle xCharsForTx;
static volatile portLONG lTHREEmpty = pdFALSE;
/*-----------------------------------------------------------*/
/* The ISR. Note that this is called by a wrapper written in the file
SerialISR.s79. See the WEB documentation for this port for further
information. */
__arm void vSerialISR( void );
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned portLONG ulDivisor, ulWantedClock;
xComPortHandle xReturn = serHANDLE;
extern void ( vSerialISREntry) ( void );
/* Create the queues used to hold Rx and Tx characters. */
xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
/* Initialise the THRE empty flag. */
lTHREEmpty = pdTRUE;
if(
( xRxedChars != serINVALID_QUEUE ) &&
( xCharsForTx != serINVALID_QUEUE ) &&
( ulWantedBaud != ( unsigned portLONG ) 0 )
)
{
portENTER_CRITICAL();
{
/* Setup the baud rate: Calculate the divisor value. */
ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING;
ulDivisor = configCPU_CLOCK_HZ / ulWantedClock;
/* Set the DLAB bit so we can access the divisor. */
U0LCR |= serDLAB;
/* Setup the divisor. */
U0DLL = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
ulDivisor >>= 8;
U0DLM = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
/* Turn on the FIFO's and clear the buffers. */
U0FCR = ( serFIFO_ON | serCLEAR_FIFO );
/* Setup transmission format. */
U0LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS;
/* Setup the VIC for the UART. */
VICIntSelect &= ~( serU0VIC_CHANNEL_BIT );
VICIntEnable |= serU0VIC_CHANNEL_BIT;
VICVectAddr1 = ( unsigned portLONG ) vSerialISREntry;
VICVectCntl1 = serU0VIC_CHANNEL | serU0VIC_ENABLE;
/* Enable UART0 interrupts. */
U0IER |= serENABLE_INTERRUPTS;
}
portEXIT_CRITICAL();
xReturn = ( xComPortHandle ) 1;
}
else
{
xReturn = ( xComPortHandle ) 0;
}
return xReturn;
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
{
/* The port handle is not required as this driver only supports UART0. */
( void ) pxPort;
/* Get the next character from the buffer. Return false if no characters
are available, or arrive before xBlockTime expires. */
if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
{
return pdTRUE;
}
else
{
return pdFALSE;
}
}
/*-----------------------------------------------------------*/
void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
{
signed portCHAR *pxNext;
/* NOTE: This implementation does not handle the queue being full as no
block time is used! */
/* The port handle is not required as this driver only supports UART0. */
( void ) pxPort;
( void ) usStringLength;
/* Send each character in the string, one at a time. */
pxNext = ( signed portCHAR * ) pcString;
while( *pxNext )
{
xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
pxNext++;
}
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
{
signed portBASE_TYPE xReturn;
/* The port handle is not required as this driver only supports UART0. */
( void ) pxPort;
portENTER_CRITICAL();
{
/* Is there space to write directly to the UART? */
if( lTHREEmpty == ( portLONG ) pdTRUE )
{
/* We wrote the character directly to the UART, so was
successful. */
lTHREEmpty = pdFALSE;
U0THR = cOutChar;
xReturn = pdPASS;
}
else
{
/* We cannot write directly to the UART, so queue the character.
Block for a maximum of xBlockTime if there is no space in the
queue. It is ok to block within a critical section as each
task has it's own critical section management. */
xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
/* Depending on queue sizing and task prioritisation: While we
were blocked waiting to post interrupts were not disabled. It is
possible that the serial ISR has emptied the Tx queue, in which
case we need to start the Tx off again. */
if( lTHREEmpty == ( portLONG ) pdTRUE )
{
xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
lTHREEmpty = pdFALSE;
U0THR = cOutChar;
}
}
}
portEXIT_CRITICAL();
return xReturn;
}
/*-----------------------------------------------------------*/
__arm void vSerialISR( void )
{
signed portCHAR cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
/* What caused the interrupt? */
switch( U0IIR & serINTERRUPT_SOURCE_MASK )
{
case serSOURCE_ERROR : /* Not handling this, but clear the interrupt. */
cChar = U0LSR;
break;
case serSOURCE_THRE : /* The THRE is empty. If there is another
character in the Tx queue, send it now. */
if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
{
U0THR = cChar;
}
else
{
/* There are no further characters
queued to send so we can indicate
that the THRE is available. */
lTHREEmpty = pdTRUE;
}
break;
case serSOURCE_RX_TIMEOUT :
case serSOURCE_RX : /* A character was received. Place it in
the queue of received characters. */
cChar = U0RBR;
xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
break;
default : /* There is nothing to do, leave the ISR. */
break;
}
/* Exit the ISR. If a task was woken by either a character being received
or transmitted then a context switch will occur. */
portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
/* Clear the ISR in the VIC. */
VICVectAddr = serCLEAR_VIC_INTERRUPT;
}
/*-----------------------------------------------------------*/
|
