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Topic: Generating a single wavelength of a signal whenever a button is pressed (Read 774 times) previous topic - next topic

Somark

Hi, not sure if this is the right forum but I'm dealing with signal generation which is almost audio generation.

I'm trying to make a signal generator. I have a digital set of values that I need converted to analog. Everytime I press a button I want it to spit out just that one set of values rather than continously running through the values over and over. I just want one wavelength so to say.

What I've done so far: I am using an Arduino Mega, an Adafruit MCP2745 DAC breakout board, and a Hantek Oscilloscope to verify my signal.

What I've tried so far: I've tried two methods. One being that whenever I push the button I unblock the code. This works except it can send out multiple signals at once which I do not want. Two: I calculated the time in between button presses and tried to force a delay by however long that time was. That did not work.

What I think I should do but don't know how: I think I should set up a timer interrupt that runs at the frequency of the output signal I want times the number of samples and then increment a counter in the interrupt handler. Although I think I2C has its own internal timer separate from that of the Arduino timers so I'm also not sure how to access that timer
I must admit though that my google-fu skills are lacking and I'm not sure where to find documentation on that. If someone could perhaps link documentation and maybe sample code on how to do that it'd be much appreciated

Heres my code:
Code: [Select]

#include <Wire.h>
#include <Adafruit_MCP4725.h>

Adafruit_MCP4725 dac;

#define DAC_RESOLUTION    (9)

const int buttonPin = 2;     // the number of the pushbutton pin
int button = 0;
int timerCheck = 0;
int timerRunning=0;
unsigned long startTime;
unsigned long endTime;
unsigned long duration;

const PROGMEM uint16_t DACLookup_FullSine_9Bit[512] =
{
  939, 945, 946, 947, 951, 956,
962, 967, 973, 978, 983, 989, 994, 1000, 1005, 1015,
1024, 1034, 1043, 1053, 1062, 1075, 1087, 1100, 1112, 1121,
1126, 1131, 1136, 1141, 1146, 1151, 1156, 1164, 1172, 1179,
1187, 1194, 1202, 1209, 1216, 1222, 1229, 1235, 1241, 1248,
1254, 1260, 1264, 1268, 1271, 1275, 1279, 1283, 1287, 1286,
1284, 1281, 1279, 1276, 1274, 1271, 1268, 1266, 1263, 1261,
1258, 1256, 1253, 1251, 1246, 1242, 1237, 1232, 1227, 1222,
1218, 1215, 1211, 1207, 1203, 1199, 1195, 1191, 1184, 1178,
1171, 1165, 1159, 1152, 1146, 1141, 1136, 1130, 1125, 1120,
1115, 1110, 1103, 1096, 1088, 1080, 1073, 1065, 1057, 1049,
1040, 1030, 1021, 1012, 1004, 995, 987, 982, 978, 974,
970, 966, 963, 959, 955, 952, 949, 945, 942, 939,
938, 939, 940, 941, 943, 944, 945, 946, 946, 946,
946, 946, 946, 946, 946, 947, 950, 952, 954, 956,
958, 960, 962, 964, 965, 965, 965, 965, 965, 965,
963, 960, 957, 954, 951, 947, 944, 941, 938, 932,
926, 920, 913, 907, 901, 894, 885, 865, 820, 733,
606, 555, 507, 632, 697, 752, 807, 896, 977, 1023,
1069, 1127, 1237, 1347, 1457, 2085, 2246, 2474, 2549, 2595,
2641, 2695, 3083, 3135, 3187, 3217, 3315, 3403, 3492, 3581,
3804, 3847, 3890, 3798, 3443, 3453, 3297, 3053, 2819, 2810,
2225, 2258, 1892, 1734, 1625, 998, 903, 355, 376, 203,
30, 33, 61, 90, 119, 160, 238, 275, 292, 309,
325, 343, 371, 399, 429, 484, 542, 602, 652, 703,
758, 802, 838, 856, 875, 895, 917, 938, 967, 1016,
1035, 1041, 1047, 1054, 1060, 1066, 1066, 1064, 1061, 1058,
1056, 1053, 1051, 1048, 1046, 1043, 1041, 1038, 1035, 1033,
1030, 1028, 1025, 1022, 1019, 1017, 1014, 1011, 1008, 1006,
1003, 1001, 999, 998, 996, 994, 993, 991, 990, 988,
986, 985, 983, 981, 978, 976, 973, 971, 968, 966,
963, 963, 963, 963, 963, 963, 963, 963, 963, 963,
963, 963, 963, 963, 963, 963, 963, 963, 963, 963,
964, 965, 966, 967, 968, 969, 970, 971, 972, 974,
976, 978, 980, 989, 991, 993, 995,
997, 999, 1002, 1006, 1011, 1015, 1019, 1023, 1028, 1032,
1036, 1040, 1045, 1050, 1055, 1059, 1064, 1069, 1076, 1082,
1088, 1095, 1101, 1107, 1114, 1120, 1126, 1132, 1141, 1149,
1158, 1166, 1173, 1178, 1183, 1188, 1193, 1198, 1203, 1208,
1214, 1221, 1246, 1250, 1254, 1259, 1263,
1269, 1278, 1286, 1294, 1303, 1309, 1315, 1322, 1328, 1334,
1341, 1343, 1353, 1355, 1357, 1359,
1359, 1359, 1359, 1359, 1358, 1356, 1354, 1352, 1350, 1347,
1345, 1343, 1341, 1327, 1324,
1322, 1320, 1317, 1315, 1312, 1307, 1301, 1294, 1288, 1281,
1275, 1270, 1265, 1260, 1256, 1251, 1246, 1240, 1233, 1227,
1221, 1214, 1208, 1201, 1194, 1186, 1178, 1170, 1162, 1154,
1148, 1144, 1140, 1136, 1131, 1127, 1123, 1118, 1114, 1107,
1099, 1090, 1082, 1074, 1069, 1064, 1058, 1053, 1048, 1043,
1038, 1034, 1029, 1025, 1021, 1017, 1013, 1009, 1005, 1001,
997, 994, 990, 991, 992, 994, 996, 997, 999, 998,
997, 996, 995, 994, 993, 991, 990, 989, 989, 989,
989, 988, 986, 984, 983, 981, 980, 1002,
1005, 1008, 1012
};


void setup(void) {
  Serial.begin(9600);
  dac.begin(0x62);
pinMode(buttonPin, INPUT);
  Serial.println("Generating a pulse");
}

void loop(void) {
if(timerCheck==0){
  if (timerRunning == 0 && digitalRead(button) == LOW){ // button pressed & timer not running already
  startTime = millis();
  timerRunning = 1;
  }
  else
  if (timerRunning == 1 && digitalRead(button) == HIGH){ // timer running, button released
  endTime = millis();
  timerRunning = 0;
  duration = endTime - startTime;
  Serial.print ("button press time in milliseconds: ");
  Serial.println (duration);
  timerCheck=1;
  }
  }   
  uint16_t i;
   
    #if DAC_RESOLUTION == 9
      for (i = 0; i < 512; i++)
      {
        dac.setVoltage(pgm_read_word(&(DACLookup_FullSine_9Bit[i])), false);
      }
    #else    // Use 8-bit data if nothing else is specified
      for (i = 0; i < 256; i++)
      {
        dac.setVoltage(pgm_read_word(&(DACLookup_FullSine_8Bit[i])), false);
      }
    #endif
    delay (duration);
}

DVDdoug

I'd make a function that writes one cycle.  Call that function when the button is pushed.    You will need to debounce the button.

Quote
Although I think I2C has its own internal timer separate from that of the Arduino timers so I'm also not sure how to access that timer
No, the sample rate depends on how fast you send it commands (or how long you wait between commands).

Quote
I'm not sure where to find documentation on that.
Here is the MCP2745 datasheet.

Somark

I'd make a function that writes one cycle.  Call that function when the button is pushed.    You will need to debounce the button.
No, the sample rate depends on how fast you send it commands (or how long you wait between commands).

Here is the MCP2745 datasheet.
Ok, so no timer interrupts needed. Would making a function that writes one cycle be as simple as using analogWrite(); with a for loop to go through each value of my table?

Somark

Code: [Select]


#include <Wire.h>
#include <Adafruit_MCP4725.h>

Adafruit_MCP4725 dac;
#define TIMER_CLOCK_FREQ 16000000
#define DAC_RESOLUTION    (9)

const int ledPin=13;
const int buttonPin = 2;     // the number of the pushbutton pin
int buttonState;             // the current reading from the input pin
int lastButtonState = LOW;   // the previous reading from the input pin


unsigned long lastDebounceTime = 0;
unsigned long debounceDelay = 50;   


const PROGMEM uint16_t Table[512] =
{
  939, 945, 946, 947, 951, 956,
962, 967, 973, 978, 983, 989, 994, 1000, 1005, 1015,
1024, 1034, 1043, 1053, 1062, 1075, 1087, 1100, 1112, 1121,
1126, 1131, 1136, 1141, 1146, 1151, 1156, 1164, 1172, 1179,
1187, 1194, 1202, 1209, 1216, 1222, 1229, 1235, 1241, 1248,
1254, 1260, 1264, 1268, 1271, 1275, 1279, 1283, 1287, 1286,
1284, 1281, 1279, 1276, 1274, 1271, 1268, 1266, 1263, 1261,
1258, 1256, 1253, 1251, 1246, 1242, 1237, 1232, 1227, 1222,
1218, 1215, 1211, 1207, 1203, 1199, 1195, 1191, 1184, 1178,
1171, 1165, 1159, 1152, 1146, 1141, 1136, 1130, 1125, 1120,
1115, 1110, 1103, 1096, 1088, 1080, 1073, 1065, 1057, 1049,
1040, 1030, 1021, 1012, 1004, 995, 987, 982, 978, 974,
970, 966, 963, 959, 955, 952, 949, 945, 942, 939,
938, 939, 940, 941, 943, 944, 945, 946, 946, 946,
946, 946, 946, 946, 946, 947, 950, 952, 954, 956,
958, 960, 962, 964, 965, 965, 965, 965, 965, 965,
963, 960, 957, 954, 951, 947, 944, 941, 938, 932,
926, 920, 913, 907, 901, 894, 885, 865, 820, 733,
606, 555, 507, 632, 697, 752, 807, 896, 977, 1023,
1069, 1127, 1237, 1347, 1457, 2085, 2246, 2474, 2549, 2595,
2641, 2695, 3083, 3135, 3187, 3217, 3315, 3403, 3492, 3581,
3804, 3847, 3890, 3798, 3443, 3453, 3297, 3053, 2819, 2810,
2225, 2258, 1892, 1734, 1625, 998, 903, 355, 376, 203,
30, 33, 61, 90, 119, 160, 238, 275, 292, 309,
325, 343, 371, 399, 429, 484, 542, 602, 652, 703,
758, 802, 838, 856, 875, 895, 917, 938, 967, 1016,
1035, 1041, 1047, 1054, 1060, 1066, 1066, 1064, 1061, 1058,
1056, 1053, 1051, 1048, 1046, 1043, 1041, 1038, 1035, 1033,
1030, 1028, 1025, 1022, 1019, 1017, 1014, 1011, 1008, 1006,
1003, 1001, 999, 998, 996, 994, 993, 991, 990, 988,
986, 985, 983, 981, 978, 976, 973, 971, 968, 966,
963, 963, 963, 963, 963, 963, 963, 963, 963, 963,
963, 963, 963, 963, 963, 963, 963, 963, 963, 963,
964, 965, 966, 967, 968, 969, 970, 971, 972, 974,
976, 978, 980, 989, 991, 993, 995,
997, 999, 1002, 1006, 1011, 1015, 1019, 1023, 1028, 1032,
1036, 1040, 1045, 1050, 1055, 1059, 1064, 1069, 1076, 1082,
1088, 1095, 1101, 1107, 1114, 1120, 1126, 1132, 1141, 1149,
1158, 1166, 1173, 1178, 1183, 1188, 1193, 1198, 1203, 1208,
1214, 1221, 1246, 1250, 1254, 1259, 1263,
1269, 1278, 1286, 1294, 1303, 1309, 1315, 1322, 1328, 1334,
1341, 1343, 1353, 1355, 1357, 1359,
1359, 1359, 1359, 1359, 1358, 1356, 1354, 1352, 1350, 1347,
1345, 1343, 1341, 1327, 1324,
1322, 1320, 1317, 1315, 1312, 1307, 1301, 1294, 1288, 1281,
1275, 1270, 1265, 1260, 1256, 1251, 1246, 1240, 1233, 1227,
1221, 1214, 1208, 1201, 1194, 1186, 1178, 1170, 1162, 1154,
1148, 1144, 1140, 1136, 1131, 1127, 1123, 1118, 1114, 1107,
1099, 1090, 1082, 1074, 1069, 1064, 1058, 1053, 1048, 1043,
1038, 1034, 1029, 1025, 1021, 1017, 1013, 1009, 1005, 1001,
997, 994, 990, 991, 992, 994, 996, 997, 999, 998,
997, 996, 995, 994, 993, 991, 990, 989, 989, 989,
989, 988, 986, 984, 983, 981, 980, 1002,
1005, 1008, 1012
};


void setup(void) {
  Serial.begin(9600);
  dac.begin(0x62);
pinMode(buttonPin, INPUT);
pinMode(ledPin, OUTPUT);
  Serial.println("Generating a pulse");
}

void RunSignal(){
  Serial.println("Worked");
  uint16_t i;
   
    #if DAC_RESOLUTION == 9
      for (i = 0; i < 512; i++)
      {
        dac.setVoltage(pgm_read_word(&(Table[i])), false);
      }
      #endif

      detachInterrupt(RunSignal);
}


void loop(void) {
buttonState = digitalRead(buttonPin);


      if (buttonState == HIGH) {
        digitalWrite(ledPin, HIGH);
Serial.println("Yay?");
        attachInterrupt(digitalPinToInterrupt(2), RunSignal, RISING);
}
else{
         digitalWrite(ledPin, LOW);
}

}



This code should work right? Whenever the button is pressed call function RunSignal(); and the function RunSignal(); consists of changing the voltage of the DAC output through each value of the table.

Unfortunately I get no reading on my oscilloscope whenever I press the button. And my led refuses to turn on no matter how many times I push the button so it appears to be stuck in the interrupt. Any idea what I'm doing wrong?

Grumpy_Mike

Where do you ever change the value in the variable lastButtonState?

I would remove the conditional compilation as well.

Somark

Yep, I fixed that but it still isn't working.

Code: [Select]

#include <Wire.h>
#include <Adafruit_MCP4725.h>

Adafruit_MCP4725 dac;
#define TIMER_CLOCK_FREQ 16000000
#define DAC_RESOLUTION    (9)

const int ledPin=13;
const int buttonPin = 2;     // the number of the pushbutton pin
int buttonState;             // the current reading from the input pin
int lastButtonState = LOW;   // the previous reading from the input pin


unsigned long lastDebounceTime = 0;
unsigned long debounceDelay = 50;   


const PROGMEM uint16_t Table[512] =
{
  939, 945, 946, 947, 951, 956,
962, 967, 973, 978, 983, 989, 994, 1000, 1005, 1015,
1024, 1034, 1043, 1053, 1062, 1075, 1087, 1100, 1112, 1121,
1126, 1131, 1136, 1141, 1146, 1151, 1156, 1164, 1172, 1179,
1187, 1194, 1202, 1209, 1216, 1222, 1229, 1235, 1241, 1248,
1254, 1260, 1264, 1268, 1271, 1275, 1279, 1283, 1287, 1286,
1284, 1281, 1279, 1276, 1274, 1271, 1268, 1266, 1263, 1261,
1258, 1256, 1253, 1251, 1246, 1242, 1237, 1232, 1227, 1222,
1218, 1215, 1211, 1207, 1203, 1199, 1195, 1191, 1184, 1178,
1171, 1165, 1159, 1152, 1146, 1141, 1136, 1130, 1125, 1120,
1115, 1110, 1103, 1096, 1088, 1080, 1073, 1065, 1057, 1049,
1040, 1030, 1021, 1012, 1004, 995, 987, 982, 978, 974,
970, 966, 963, 959, 955, 952, 949, 945, 942, 939,
938, 939, 940, 941, 943, 944, 945, 946, 946, 946,
946, 946, 946, 946, 946, 947, 950, 952, 954, 956,
958, 960, 962, 964, 965, 965, 965, 965, 965, 965,
963, 960, 957, 954, 951, 947, 944, 941, 938, 932,
926, 920, 913, 907, 901, 894, 885, 865, 820, 733,
606, 555, 507, 632, 697, 752, 807, 896, 977, 1023,
1069, 1127, 1237, 1347, 1457, 2085, 2246, 2474, 2549, 2595,
2641, 2695, 3083, 3135, 3187, 3217, 3315, 3403, 3492, 3581,
3804, 3847, 3890, 3798, 3443, 3453, 3297, 3053, 2819, 2810,
2225, 2258, 1892, 1734, 1625, 998, 903, 355, 376, 203,
30, 33, 61, 90, 119, 160, 238, 275, 292, 309,
325, 343, 371, 399, 429, 484, 542, 602, 652, 703,
758, 802, 838, 856, 875, 895, 917, 938, 967, 1016,
1035, 1041, 1047, 1054, 1060, 1066, 1066, 1064, 1061, 1058,
1056, 1053, 1051, 1048, 1046, 1043, 1041, 1038, 1035, 1033,
1030, 1028, 1025, 1022, 1019, 1017, 1014, 1011, 1008, 1006,
1003, 1001, 999, 998, 996, 994, 993, 991, 990, 988,
986, 985, 983, 981, 978, 976, 973, 971, 968, 966,
963, 963, 963, 963, 963, 963, 963, 963, 963, 963,
963, 963, 963, 963, 963, 963, 963, 963, 963, 963,
964, 965, 966, 967, 968, 969, 970, 971, 972, 974,
976, 978, 980, 989, 991, 993, 995,
997, 999, 1002, 1006, 1011, 1015, 1019, 1023, 1028, 1032,
1036, 1040, 1045, 1050, 1055, 1059, 1064, 1069, 1076, 1082,
1088, 1095, 1101, 1107, 1114, 1120, 1126, 1132, 1141, 1149,
1158, 1166, 1173, 1178, 1183, 1188, 1193, 1198, 1203, 1208,
1214, 1221, 1246, 1250, 1254, 1259, 1263,
1269, 1278, 1286, 1294, 1303, 1309, 1315, 1322, 1328, 1334,
1341, 1343, 1353, 1355, 1357, 1359,
1359, 1359, 1359, 1359, 1358, 1356, 1354, 1352, 1350, 1347,
1345, 1343, 1341, 1327, 1324,
1322, 1320, 1317, 1315, 1312, 1307, 1301, 1294, 1288, 1281,
1275, 1270, 1265, 1260, 1256, 1251, 1246, 1240, 1233, 1227,
1221, 1214, 1208, 1201, 1194, 1186, 1178, 1170, 1162, 1154,
1148, 1144, 1140, 1136, 1131, 1127, 1123, 1118, 1114, 1107,
1099, 1090, 1082, 1074, 1069, 1064, 1058, 1053, 1048, 1043,
1038, 1034, 1029, 1025, 1021, 1017, 1013, 1009, 1005, 1001,
997, 994, 990, 991, 992, 994, 996, 997, 999, 998,
997, 996, 995, 994, 993, 991, 990, 989, 989, 989,
989, 988, 986, 984, 983, 981, 980, 1002,
1005, 1008, 1012
};


void setup(void) {
  Serial.begin(9600);
  dac.begin(0x62);
pinMode(buttonPin, INPUT);
pinMode(ledPin, OUTPUT);
  Serial.println("Generating a pulse");
}

void RunSignal(){
  Serial.println("Worked");
  uint16_t i;
   
    #if DAC_RESOLUTION == 9
      for (i = 0; i < 512; i++)
      {
        dac.setVoltage(pgm_read_word(&(Table[i])), false);
      }
      #endif

      detachInterrupt(RunSignal);
}


void loop(void) {
buttonState = digitalRead(buttonPin);


      if (buttonState == HIGH) {
        digitalWrite(ledPin, HIGH);
Serial.println("Yay?");
        attachInterrupt(digitalPinToInterrupt(2), RunSignal, RISING);
}
else{
         digitalWrite(ledPin, LOW);
}

}


The LED turns on once so I know the timer interrupt started but it appears to be stuck in the timer interrupt. It also doesn't work since I fixed my debouncing code.

Grumpy_Mike

What do you think the
Code: [Select]
detachInterrupt(RunSignal);
is doing?
Why did you put this in? Remove it.

You are not doing what I told you about lastButtonState.

When you call a function as part of an interrupt service routine the interrupts for the whole processor are disabled, therefore the I2C will not run. So don't do it.

This is how you call running the function once.
Code: [Select]
void loop(void) {
buttonState = digitalRead(buttonPin);

      if (buttonState == HIGH && lastButtonState == LOW) {
        digitalWrite(ledPin, HIGH);
        RunSignal();       
}
else{
         digitalWrite(ledPin, LOW);
}
   lastButtonState = buttonState;
}

Note there is no debouncing in this but it should produce something you can see on your scope.

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