Navigation :

Near/mid-field Sounds

Near/mid-field sounds refer to rather directed areas where you wish to detect and sense for audio. Even though we are using similar types of electret microphones, we're not explicitly recording audio in this recipe.

Instead, we are detecting the sound pressure level (SPL) of the area the microphone is pointed at, which in turn generates an analog voltage change that our Photon can read.

Again, consider how such a sensor can be used – it's not just good for detecting voices, but also knocks, footsteps, perhaps even wind, once you design the right porting and enclosure for it!

More information on this sensor: https://www.adafruit.com/product/1063

Libraries Used

(learn how to import them in the Build IDE):

none

Code

 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


// how long between each log update? feel free to change this value,
// but this must not be anything less than 1000 milliseconds!
#define INTERVAL_BETWEEN_LOGS 5000

// initialise the timer
Timer dataTimer(INTERVAL_BETWEEN_LOGS, doDataUpdate);


// code in this setup function runs just once, when Photon is powered up or reset
void setup() {
    Serial.begin(9600);         // Open a connection via the Serial port / USB cable – useful for debugging
    delay(5000);                // Common practice to allow board to 'settle' after connecting online

    dataTimer.start();

    // note: analogue pins do not need to be initialised as they are INPUTs by default
}

// code in this loop function runs forever, until you cut power!
// for the A/D blackbox, there is nothing to do in here because data updates are handled by our timer
void loop() {

}

// doDataUpdate runs every interval set in INTERVAL_BETWEEN_LOGS
void doDataUpdate() {
    // IMPORTANT: to prevent server overload, the Particle cloud can only accept
    // update rates of once per second, with the option to 'burst' 4 updates in a
    // second (but then you'll get blocked for the next 4 seconds). 'Ration' your
    // INTERVAL_BETWEEN_LOGS and the number of readings you are publishing; in our
    // default example, we are frugally using just 1 publish, by concatenating
    // all the data we want into a single publish statement

    // first we save what we want to read into temporary variables first.
    // feel free to add/remove these lines as you see fit in your application:

    int A0State = analogRead(A0); // read an analogue range (0-4095) from A0

    // now we form the concatenated string to put them all together. This String
    // must NOT exceed 255 characters!
    String output = "A0:" + String(A0State);

    // prints this out the Serial port (coolterm) for us HUMANS to verify and
    // debug; comment the next line if you don't want to see it in Coolterm
    Serial.println(output);

    // finally, send it out (and have sensored.mdit.space receive it):
    Particle.publish("sensorData", output);
}