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filt_test.c
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1 /*
2  * "Copyright (c) 2008 Robert B. Reese, Bryan A. Jones, J. W. Bruce ("AUTHORS")"
3  * All rights reserved.
4  * (R. Reese, reese_AT_ece.msstate.edu, Mississippi State University)
5  * (B. A. Jones, bjones_AT_ece.msstate.edu, Mississippi State University)
6  * (J. W. Bruce, jwbruce_AT_ece.msstate.edu, Mississippi State University)
7  *
8  * Permission to use, copy, modify, and distribute this software and its
9  * documentation for any purpose, without fee, and without written agreement is
10  * hereby granted, provided that the above copyright notice, the following
11  * two paragraphs and the authors appear in all copies of this software.
12  *
13  * IN NO EVENT SHALL THE "AUTHORS" BE LIABLE TO ANY PARTY FOR
14  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
15  * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE "AUTHORS"
16  * HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
17  *
18  * THE "AUTHORS" SPECIFICALLY DISCLAIMS ANY WARRANTIES,
19  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
20  * AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
21  * ON AN "AS IS" BASIS, AND THE "AUTHORS" HAS NO OBLIGATION TO
22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS."
23  *
24  * Please maintain this header in its entirety when copying/modifying
25  * these files.
26  *
27  *
28  */
29 
30 #include "pic24_all.h"
31 
32 /** \file
33 Low-pass RC Filter test.
34 RB2 generates a pulse train that is read by RB3, the
35 external RC filter is assumed to be on the RB3 input.
36 
37 */
38 
39 #define CONFIG_TOUT() CONFIG_RB2_AS_DIG_OUTPUT()
40 #define TOUT _LATB2 //output state
41 
42 #define TIN _RB3 //test in
43 #define CONFIG_TIN() CONFIG_RB3_AS_DIG_INPUT();
44 
45 #define TPW 1 // in ms, pulsewidth of TOUT
46 
47 int main (void) {
48  uint8_t u8_oldvalueTIN;
49  configBasic(HELLO_MSG);
50  TOUT = 1; // TOUT drives TIN
51  CONFIG_TIN();
52  CONFIG_TOUT();
53  DELAY_MS(10); //wait for output to stablize because of filter
54  u8_oldvalueTIN = TIN;
55  while (1) {
56  TOUT = !TOUT;
57  DELAY_MS(TPW);
58  if (u8_oldvalueTIN != TIN) {
59  u8_oldvalueTIN = TIN;
60  outString("*");
61  }
62  }
63 }