Working with the dimensions of the tops of the plinths for display.
The blog
Working with the dimensions of the tops of the plinths for display.
So…it seems that the combination of XBee RSSI data and the Mozzi synth can only produce intermittent or pulsing sound and doesn’t allow for constant tones, as witnessed by the following video demos. All the data that has to be sent from Arduino to the XBee in order to get it to send and receive packets is causing the audio to stutter.
To get the tones required for the final piece, the circuits will need to be created using SX1278 LoRa modules instead. These will connect the four Space Rocks via an additional transmitter, and based around this circuit:
This should guarantee that the Mozzi synths can play continuous tones rather than interrupted pulses. Although I’ll now need to find a way to fit 4+” 433MHz antennaes into the Space Rocks too.
Thinking about the network that connects the Space Rocks. Initially I started with the idea of all four rocks connecting equally, which isn’t really possible.
The network will be connected as a star formation, as shown here:
Similar to this diagram I drew a while back:
Ending up with something akin to this:
The co-ordinator would be loaded with one Mozzi synth, and the same synth is installed on the three nodes, with each node changing a different filter (attack, decay and sustain). The code for this looks like so:
Co-ordinator:
// include all libraries #include <XBee.h> #include <SoftwareSerial.h> #include <MozziGuts.h> #include <Oscil.h> #include <EventDelay.h> #include <ADSR.h> #include <tables/sin8192_int8.h> #include <mozzi_rand.h> #include <mozzi_midi.h> // uncomment the following line to enable debug output #define DEBUG // debug macros #ifdef DEBUG #define DEBUG_BEGIN(x) Serial.begin (x) #define DEBUG_PRINT(x) Serial.print (x) #define DEBUG_PRINTLN(x) Serial.println (x) #else #define DEBUG_BEGIN(x) #define DEBUG_PRINT(x) #define DEBUG_PRINTLN(x) #endif // Mozzi control rate in Hz #define CONTROL_RATE 128 Oscil <8192, AUDIO_RATE> aOscil(SIN8192_DATA); // for triggering the envelope EventDelay noteDelay; ADSR <CONTROL_RATE, CONTROL_RATE> envelope; boolean note_is_on = true; byte gain; // XBee packet reception timeout in ms #define XBEE_PACKET_TIMEOUT 250 // RSSI reading timeout in us #define RSSI_READING_TIMEOUT 100 // Arduino pin connections #define RSSI_PIN 5 #define XBEE_DOUT 6 #define XBEE_DIN 7 #define AUDIO_PIN 9 // freqency range bounds in Hz #define ATTACK_LOW 0 #define ATTACK_HIGH 1000 #define DECAY_LOW 0 #define DECAY_HIGH 1000 #define SUSTAIN_LOW 0 #define SUSTAIN_HIGH 1000 // RSSI range bounds int RSSI_LOW = 25; int RSSI_HIGH = 45; int RSSI_LOW_2 = 25; int RSSI_HIGH_2 = 45; int RSSI_LOW_3 = 25; int RSSI_HIGH_3 = 45; // number of samples for moving average filter #define SAMPLES 10 // XBee object instance XBee xbee = XBee(); // address of destination XBee (node address) XBeeAddress64 addr64 = XBeeAddress64(0x0013a200, 0x40A58A5D); // packet to be sent to coordinator uint8_t ping[] = {0xAA, 0xAA}; ZBTxRequest pingRequest = ZBTxRequest(addr64, ping, sizeof(ping)); XBeeResponse response = XBeeResponse(); // create reusable response objects for responses we expect to handle ZBRxResponse rx = ZBRxResponse(); // SoftwareSerial port SoftwareSerial beeSerial(XBEE_DOUT, XBEE_DIN); // Mozzi sine oscillator //Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin(SIN2048_DATA); // array to hold RSSI samples for filter float rssiSamples[SAMPLES]; // current position in array int pos = 0; float rssiAttack = 0; float rssiDecay = 0; float rssiSustain = 0; // moving average filter float movingAverage(float* arr, int newValue, int pos) { // update array arr[pos] = newValue; // get array total float total = 0; for (int i = 0; i < SAMPLES; i++) { total += arr[i]; } // get average float average = total / (float)SAMPLES; return (average); } void setup() { randSeed(); // fresh random noteDelay.set(2000); // begin Serial communication with PC DEBUG_BEGIN(9600); // set pin modes pinMode(RSSI_PIN, INPUT); pinMode(AUDIO_PIN, OUTPUT); // initialize array contents to 0 for (int i = 0; i < SAMPLES; i++) { rssiSamples[i] = 0; } // begin Serial communication with XBee beeSerial.begin(9600); // set XBee serial port xbee.setSerial(beeSerial); // start Mozzi startMozzi(CONTROL_RATE); // set output frequency to the lowest value //aSin.setFreq(FREQ_LOW); } unsigned int duration, attack, decay, sustain, release_ms; void updateControl() { // send packet to node xbee.send(pingRequest); // try to receive pong packet if (xbee.readPacket(XBEE_PACKET_TIMEOUT)) { if (xbee.getResponse().isAvailable()) { if (xbee.getResponse().getApiId() == 16) { xbee.getResponse().getZBRxResponse(rx); uint16_t sender = rx.getRemoteAddress16(); //DEBUG_PRINTLN(sender); if (sender == 18431) { // try to read raw RSSI value int rssiRaw = pulseIn(RSSI_PIN, HIGH, RSSI_READING_TIMEOUT); // check if the read was successful if (rssiRaw > 0) { if (rssiRaw <= RSSI_LOW) { RSSI_LOW = rssiRaw; } if (rssiRaw >= RSSI_HIGH) { RSSI_HIGH = rssiRaw; } // if so, map the raw RSSI value to frequency range int rssiMapped = map(rssiRaw, RSSI_LOW, RSSI_HIGH, ATTACK_LOW, ATTACK_HIGH); // filter RSSI value rssiAttack = movingAverage(rssiSamples, rssiMapped, pos); // check array position overflow if (pos == SAMPLES - 1) { pos = 0; } else { pos++; } // print both values to PC for debugging /*DEBUG_PRINT(rssiRaw); DEBUG_PRINT('\t'); DEBUG_PRINT(rssiMapped); DEBUG_PRINT('\t'); DEBUG_PRINTLN(rssiFiltered);*/ } } else if (sender == 24063) { int rssiRaw = pulseIn(RSSI_PIN, HIGH, RSSI_READING_TIMEOUT); // check if the read was successful if (rssiRaw > 0) { if (rssiRaw <= RSSI_LOW_2) { RSSI_LOW_2 = rssiRaw; } if (rssiRaw >= RSSI_HIGH_2) { RSSI_HIGH_2 = rssiRaw; } // if so, map the raw RSSI value to frequency range int rssiMapped = map(rssiRaw, RSSI_LOW_2, RSSI_HIGH_2, DECAY_LOW, DECAY_HIGH); // filter RSSI value rssiDecay = movingAverage(rssiSamples, rssiMapped, pos); // check array position overflow if (pos == SAMPLES - 1) { pos = 0; } else { pos++; } // print both values to PC for debugging /*DEBUG_PRINT(rssiRaw); DEBUG_PRINT('\t'); DEBUG_PRINT(rssiMapped); DEBUG_PRINT('\t'); DEBUG_PRINTLN(rssiFiltered);*/ } } else if (sender == 20479) { int rssiRaw = pulseIn(RSSI_PIN, HIGH, RSSI_READING_TIMEOUT); // check if the read was successful if (rssiRaw > 0) { if (rssiRaw <= RSSI_LOW_3) { RSSI_LOW_3 = rssiRaw; } if (rssiRaw >= RSSI_HIGH_3) { RSSI_HIGH_3 = rssiRaw; } // if so, map the raw RSSI value to frequency range int rssiMapped = map(rssiRaw, RSSI_LOW_3, RSSI_HIGH_3, SUSTAIN_LOW, SUSTAIN_HIGH); // filter RSSI value rssiSustain = movingAverage(rssiSamples, rssiMapped, pos); // check array position overflow if (pos == SAMPLES - 1) { pos = 0; } else { pos++; } // print both values to PC for debugging /*DEBUG_PRINT(rssiRaw); DEBUG_PRINT('\t'); DEBUG_PRINT(rssiMapped); DEBUG_PRINT('\t'); DEBUG_PRINTLN(rssiFiltered);*/ } } } } } if (noteDelay.ready()) { // choose envelope levels byte attack_level = rand(128) + 127; byte decay_level = rand(255); envelope.setADLevels(attack_level, decay_level); // generate a random new adsr parameter value in milliseconds int r = rand(1000) - rand(1000); unsigned int new_value = abs(r); release_ms = new_value; // randomly choose one of the adsr parameters and set the new value /*switch (rand(4)){ case 0: attack = new_value; break; case 1: decay = new_value; break; case 2: sustain = new_value; break; case 3: release_ms = new_value; break; }*/ attack = rssiAttack; decay = rssiDecay; sustain = rssiSustain; envelope.setTimes(attack, decay, sustain, release_ms); envelope.noteOn(); byte midi_note = rand(107) + 20; aOscil.setFreq((int)mtof(midi_note)); DEBUG_PRINT("ATTACK - "); DEBUG_PRINTLN(attack); DEBUG_PRINT("DECAY - "); DEBUG_PRINTLN(decay); DEBUG_PRINT("SUSTAIN - "); DEBUG_PRINTLN(sustain); // print to screen /*Serial.print("midi_note\t"); Serial.println(midi_note); Serial.print("attack_level\t"); Serial.println(attack_level); Serial.print("decay_level\t"); Serial.println(decay_level); Serial.print("attack\t\t"); Serial.println(attack); Serial.print("decay\t\t"); Serial.println(decay); Serial.print("sustain\t\t"); Serial.println(sustain); Serial.print("release\t\t"); Serial.println(release_ms); Serial.println();*/ noteDelay.start(attack + decay + sustain + release_ms); } envelope.update(); gain = envelope.next(); // this is where it's different to an audio rate envelope } int updateAudio() { return (int) (gain * aOscil.next()) >> 8; } void loop() { audioHook(); }
And the three nodes:
// include all libraries #include <XBee.h> #include <SoftwareSerial.h> #include <MozziGuts.h> #include <Oscil.h> // oscillator template #include <tables/sin2048_int8.h> // sine table for oscillator #include <RollingAverage.h> #include <ControlDelay.h> // uncomment the following line to enable debug output #define DEBUG // debug macros #ifdef DEBUG #define DEBUG_BEGIN(x) Serial.begin (x) #define DEBUG_PRINT(x) Serial.print (x) #define DEBUG_PRINTLN(x) Serial.println (x) #else #define DEBUG_BEGIN(x) #define DEBUG_PRINT(x) #define DEBUG_PRINTLN(x) #endif unsigned int echo_cells_1 = 32; unsigned int echo_cells_2 = 60; unsigned int echo_cells_3 = 127; // Mozzi control rate in Hz ControlDelay <128, int> kDelay; // 2seconds // oscils to compare bumpy to averaged control input Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin0(SIN2048_DATA); Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin1(SIN2048_DATA); Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin2(SIN2048_DATA); Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin3(SIN2048_DATA); // use: RollingAverage <number_type, how_many_to_average> myThing RollingAverage <int, 32> kAverage; // how_many_to_average has to be power of 2 int averaged; float rssiFiltered = 512; // XBee packet reception timeout in ms #define XBEE_PACKET_TIMEOUT 250 // RSSI reading timeout in us #define RSSI_READING_TIMEOUT 100 // Arduino pin connections #define RSSI_PIN 5 #define XBEE_DOUT 6 #define XBEE_DIN 7 #define AUDIO_PIN 9 // freqency range bounds in Hz #define FREQ_LOW 512 #define FREQ_HIGH 1023 // RSSI range bounds int RSSI_LOW = 11; int RSSI_HIGH = 20; // number of samples for moving average filter #define SAMPLES 10 // XBee object instance XBee xbee = XBee(); // address of destination XBee (coordinator address) XBeeAddress64 addr64 = XBeeAddress64(0x0013a200, 0x4176E94F); // packet to be sent to coordinator uint8_t pong[] = {0xAA, 0xAA}; ZBTxRequest pongRequest = ZBTxRequest(addr64, pong, sizeof(pong)); XBeeResponse response = XBeeResponse(); // create reusable response objects for responses we expect to handle ZBRxResponse rx = ZBRxResponse(); // SoftwareSerial port SoftwareSerial beeSerial(XBEE_DOUT, XBEE_DIN); // Mozzi sine oscillator Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin(SIN2048_DATA); // array to hold RSSI samples for filter float rssiSamples[SAMPLES]; // current position in array int pos = 0; // moving average filter float movingAverage(float* arr, int newValue, int pos) { // update array arr[pos] = newValue; // get array total float total = 0; for (int i = 0; i < SAMPLES; i++) { total += arr[i]; } // get average float average = total / (float)SAMPLES; return (average); } void setup() { // begin Serial communication with PC DEBUG_BEGIN(9600); // set pin modes pinMode(RSSI_PIN, INPUT); pinMode(AUDIO_PIN, OUTPUT); // initialize array contents to 0 for (int i = 0; i < SAMPLES; i++) { rssiSamples[i] = 0; } // begin Serial communication with XBee beeSerial.begin(9600); // set XBee serial port xbee.setSerial(beeSerial); // start Mozzi kDelay.set(echo_cells_1); startMozzi(); // set output frequency to the lowest value //aSin.setFreq(FREQ_LOW); } void updateControl() { // try to receive ping packet with 250 ms timeout if (xbee.readPacket(XBEE_PACKET_TIMEOUT)) { if (xbee.getResponse().isAvailable()) { //DEBUG_PRINTLN(xbee.getResponse().getApiId()); if (xbee.getResponse().getApiId() == 16) { xbee.getResponse().getZBRxResponse(rx); uint16_t sender = rx.getRemoteAddress16(); //DEBUG_PRINTLN(sender); } } // try to read raw RSSI value with 100 us timeout int rssiRaw = pulseIn(RSSI_PIN, LOW, RSSI_READING_TIMEOUT); // check if the read was successful if (rssiRaw > 0) { // if so, map the raw RSSI value to frequency range if (rssiRaw <= RSSI_LOW) { RSSI_LOW = rssiRaw; } if (rssiRaw >= RSSI_HIGH) { RSSI_HIGH = rssiRaw; } int rssiMapped = map(rssiRaw, RSSI_LOW, RSSI_HIGH, FREQ_LOW, FREQ_HIGH); // filter RSSI value rssiFiltered = movingAverage(rssiSamples, rssiMapped, pos); // check array position overflow if (pos == SAMPLES - 1) { pos = 0; } else { pos++; } // print both values to PC for debugging /*DEBUG_PRINT(rssiRaw); DEBUG_PRINT('\t'); DEBUG_PRINT(rssiMapped); DEBUG_PRINT('\t'); DEBUG_PRINTLN(rssiFiltered);*/ DEBUG_PRINT(rssiFiltered); DEBUG_PRINT(" - "); DEBUG_PRINT(RSSI_LOW); DEBUG_PRINT(" - "); DEBUG_PRINTLN(RSSI_HIGH); //rssiFiltered); // adjust sine wave frequency //aSin.setFreq(rssiFiltered); } } averaged = kAverage.next(rssiFiltered); aSin0.setFreq(averaged); aSin1.setFreq(kDelay.next(averaged)); aSin2.setFreq(kDelay.read(echo_cells_2)); aSin3.setFreq(kDelay.read(echo_cells_3)); // send packet to coordinator xbee.send(pongRequest); // delay(2000); } int updateAudio() { return 3 * ((int)aSin0.next() + aSin1.next() + (aSin2.next() >> 1) + (aSin3.next() >> 2)) >> 3; //return aSin.next(); } void loop() { pong[0] = 100 >> 8 & 0xff; pong[1] = 100 & 0xff; audioHook(); }
Here’s a sneak preview of the We Are Here exhibition catalogue.
Installation proof-of-concept video.
Finally have some code that changes the synths on the Space Rock sound modules, based on the distance between Rocks.
Some ideas for the stands for the Space Rocks. Plus revised drawing of exhibition set-up. The stands would be milled from wood.
Noise Generation. Playing with Mozzi & XBee RSSI values to manipulate sound. Note sound changes as RSSI feed connected to pin D5.
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