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
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
|
/*
FreeRTOS V7.4.0 - Copyright (C) 2013 Real Time Engineers Ltd.
FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
***************************************************************************
* *
* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
* *
* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
* *
* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
* *
* Thank you for using FreeRTOS, and thank you for your support! *
* *
***************************************************************************
This file is part of the FreeRTOS distribution.
FreeRTOS is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License (version 2) as published by the
Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
>>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
distribute a combined work that includes FreeRTOS without being obliged to
provide the source code for proprietary components outside of the FreeRTOS
kernel.
FreeRTOS 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
and the FreeRTOS license exception along with FreeRTOS; if not itcan be
viewed here: http://www.freertos.org/a00114.html and also obtained by
writing to Real Time Engineers Ltd., contact details for whom are available
on the FreeRTOS WEB site.
1 tab == 4 spaces!
***************************************************************************
* *
* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
* *
* http://www.FreeRTOS.org/FAQHelp.html *
* *
***************************************************************************
http://www.FreeRTOS.org - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details.
http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, and our new
fully thread aware and reentrant UDP/IP stack.
http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems, who sell the code with commercial support,
indemnification and middleware, under the OpenRTOS brand.
http://www.SafeRTOS.com - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
*/
/*
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 char ) 0x80 )
#define serENABLE_INTERRUPTS ( ( unsigned char ) 0x03 )
#define serNO_PARITY ( ( unsigned char ) 0x00 )
#define ser1_STOP_BIT ( ( unsigned char ) 0x00 )
#define ser8_BIT_CHARS ( ( unsigned char ) 0x03 )
#define serFIFO_ON ( ( unsigned char ) 0x01 )
#define serCLEAR_FIFO ( ( unsigned char ) 0x06 )
#define serWANTED_CLOCK_SCALING ( ( unsigned long ) 16 )
/* Constants to setup and access the VIC. */
#define serU0VIC_CHANNEL ( ( unsigned long ) 0x0006 )
#define serU0VIC_CHANNEL_BIT ( ( unsigned long ) 0x0040 )
#define serU0VIC_ENABLE ( ( unsigned long ) 0x0020 )
#define serCLEAR_VIC_INTERRUPT ( ( unsigned long ) 0 )
/* Constants to determine the ISR source. */
#define serSOURCE_THRE ( ( unsigned char ) 0x02 )
#define serSOURCE_RX_TIMEOUT ( ( unsigned char ) 0x0c )
#define serSOURCE_ERROR ( ( unsigned char ) 0x06 )
#define serSOURCE_RX ( ( unsigned char ) 0x04 )
#define serINTERRUPT_SOURCE_MASK ( ( unsigned char ) 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 long 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 long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned long 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 char ) );
xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
/* Initialise the THRE empty flag. */
lTHREEmpty = pdTRUE;
if(
( xRxedChars != serINVALID_QUEUE ) &&
( xCharsForTx != serINVALID_QUEUE ) &&
( ulWantedBaud != ( unsigned long ) 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 char ) ( ulDivisor & ( unsigned long ) 0xff );
ulDivisor >>= 8;
U0DLM = ( unsigned char ) ( ulDivisor & ( unsigned long ) 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 long ) 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 char *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 char * const pcString, unsigned short usStringLength )
{
signed char *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 char * ) pcString;
while( *pxNext )
{
xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
pxNext++;
}
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char 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 == ( long ) 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 == ( long ) pdTRUE )
{
xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
lTHREEmpty = pdFALSE;
U0THR = cOutChar;
}
}
}
portEXIT_CRITICAL();
return xReturn;
}
/*-----------------------------------------------------------*/
__arm void vSerialISR( void )
{
signed char 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;
}
/*-----------------------------------------------------------*/
|
