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How to measure noise levels with Wio Terminal

Overview‚Äč

This example showing how perfectly display the Decibel Meter on the Wio Terminal.

Part list‚Äč

note

Please visit the Audio Overview for the Hardware Connection.

Features‚Äč

  • The dB can be presented in the dial plate, reading and line-chart respectively.
  • It has a guide to introduce what the number of dB mean.

Getting Started‚Äč

To get started with the Audio library for Wio Terminal, please follow through the followings:

library Installation‚Äč

  1. Install the Audio library Seeed_Arduino_Audio, Please visit the Audio Overview for more information.

  2. Install the LCD screen Library Seeed_Arduino_LCD, please visit Wio Terminal LCD for more information.

  3. Now, the library can be installed to the Arduino IDE. Open the Arduino IDE, and click sketch -> Include Library -> Add .ZIP Library, and choose the Seeed_Arduino_Audio file that you've have just downloaded.

InstallLibrary

Dispaly the dB value on the Arduino Monitor‚Äč

This example is display the dB value on the arduino Monitor, so we can have a test dB code.

note

The code is quite long, so you can just click 'copy to clipboard' then put on the Arduino IDE.

#include <Audio.h>
#include <Wire.h>
#include <SD.h>

int i;
float v[512] = {0};
float magnitude = 0;
float dB_holder;
float a_weight[512] = {0.000491601, 0.007439144, 0.026456683, 0.057237193, 0.097648235, 0.145530499, 0.19895028, 0.256192702, 0.315753433, 0.376341431, 0.436880336, 0.496502258, 0.554533348, 0.610473237, 0.663971116, 0.714800959, 0.762837753, 0.808035908, 0.85041046, 0.890021233, 0.926959868, 0.961339445, 0.993286373, 1.022934171, 1.050418819, 1.075875354, 1.099435459, 1.12122582, 1.141367062, 1.159973138, 1.177151032, 1.193000704, 1.207615207, 1.221080906, 1.233477786, 1.244879798, 1.255355228, 1.264967081, 1.273773452, 1.281827897, 1.289179783, 1.29587462, 1.301954369, 1.307457742, 1.312420463, 1.316875521, 1.320853401, 1.324382291, 1.327488281, 1.330195534, 1.332526449, 1.334501812, 1.336140927, 1.337461742, 1.338480956, 1.339214128, 1.339675764, 1.339879407, 1.33983771, 1.33956251, 1.339064892, 1.338355246, 1.337443324, 1.336338287, 1.33504875, 1.333582824, 1.331948154, 1.330151954, 1.328201037, 1.326101843, 1.323860472, 1.3214827, 1.318974007, 1.316339599, 1.313584419, 1.310713175, 1.307730349, 1.304640214, 1.301446848, 1.298154147, 1.294765835, 1.291285478, 1.28771649, 1.284062146, 1.280325589, 1.276509835, 1.272617788, 1.268652238, 1.264615874, 1.260511287, 1.256340974, 1.252107348, 1.247812737, 1.243459393, 1.239049492, 1.234585143, 1.230068386, 1.2255012, 1.220885501, 1.216223152, 1.211515958, 1.206765674, 1.201974005, 1.19714261, 1.1922731, 1.187367045, 1.182425973, 1.177451372, 1.172444693, 1.167407348, 1.162340715, 1.157246139, 1.152124932, 1.146978373, 1.141807712, 1.136614169, 1.131398936, 1.126163178, 1.120908033, 1.115634612, 1.110344003, 1.105037268, 1.099715447, 1.094379556, 1.08903059, 1.083669521, 1.078297301, 1.072914859, 1.067523108, 1.062122937, 1.05671522, 1.05130081, 1.045880542, 1.040455233, 1.035025683, 1.029592675, 1.024156975, 1.018719333, 1.013280482, 1.00784114, 1.00240201, 0.996963778, 0.991527118, 0.986092686, 0.980661126, 0.975233068, 0.969809127, 0.964389904, 0.958975988, 0.953567954, 0.948166364, 0.942771769, 0.937384705, 0.932005696, 0.926635255, 0.921273883, 0.915922069, 0.91058029, 0.905249011, 0.899928687, 0.894619763, 0.88932267, 0.88403783, 0.878765656, 0.873506548, 0.868260896, 0.863029082, 0.857811477, 0.852608441, 0.847420326, 0.842247473, 0.837090216, 0.831948877, 0.826823771, 0.821715204, 0.816623471, 0.811548862, 0.806491654, 0.80145212, 0.796430522, 0.791427115, 0.786442146, 0.781475853, 0.776528467, 0.771600212, 0.766691304, 0.761801951, 0.756932355, 0.752082709, 0.747253202, 0.742444013, 0.737655316, 0.732887277, 0.728140056, 0.723413808, 0.71870868, 0.714024813, 0.709362343, 0.704721397, 0.700102099, 0.695504567, 0.690928912, 0.686375241, 0.681843653, 0.677334244, 0.672847104, 0.668382317, 0.663939963, 0.659520116, 0.655122846, 0.650748219, 0.646396293, 0.642067124, 0.637760764, 0.633477258, 0.629216649, 0.624978975, 0.620764269, 0.616572561, 0.612403877, 0.608258238, 0.604135661, 0.600036161, 0.595959749, 0.59190643, 0.587876209, 0.583869084, 0.579885053, 0.575924108, 0.571986239, 0.568071433, 0.564179674, 0.560310942, 0.556465216, 0.552642469, 0.548842674, 0.5450658, 0.541311815, 0.537580682, 0.533872363, 0.530186816, 0.526524, 0.522883867, 0.519266371, 0.51567146, 0.512099084, 0.508549187, 0.505021714, 0.501516605, 0.498033801, 0.49457324, 0.491134857, 0.487718587, 0.484324362, 0.480952113, 0.47760177, 0.47427326, 0.47096651, 0.467681443, 0.464417985, 0.461176056, 0.457955577, 0.454756467, 0.451578645, 0.448422028, 0.445286531, 0.442172069, 0.439078556, 0.436005904, 0.432954025, 0.429922829, 0.426912226, 0.423922125, 0.420952434, 0.41800306, 0.41507391, 0.412164889, 0.409275902, 0.406406853, 0.403557647, 0.400728185, 0.397918372, 0.395128108, 0.392357295, 0.389605834, 0.386873625, 0.384160569, 0.381466565, 0.378791512, 0.37613531, 0.373497856, 0.37087905, 0.368278789, 0.36569697, 0.363133492, 0.360588252, 0.358061147, 0.355552074, 0.353060929, 0.35058761, 0.348132012, 0.345694033, 0.343273569, 0.340870517, 0.338484772, 0.336116231, 0.333764791, 0.331430348, 0.329112798, 0.326812038, 0.324527964, 0.322260474, 0.320009464, 0.31777483, 0.315556471, 0.313354282, 0.311168162, 0.308998008, 0.306843717, 0.304705188, 0.302582319, 0.300475007, 0.298383152, 0.296306653, 0.294245408, 0.292199316, 0.290168278, 0.288152193, 0.286150961, 0.284164484, 0.28219266, 0.280235393, 0.278292582, 0.276364131, 0.27444994, 0.272549913, 0.270663953, 0.268791961, 0.266933843, 0.265089501, 0.263258841, 0.261441767, 0.259638183, 0.257847996, 0.256071111, 0.254307435, 0.252556875, 0.250819337, 0.249094729, 0.247382959, 0.245683935, 0.243997567, 0.242323763, 0.240662434, 0.239013489, 0.23737684, 0.235752397, 0.234140071, 0.232539776, 0.230951422, 0.229374924, 0.227810195, 0.226257148, 0.224715697, 0.223185759, 0.221667247, 0.220160077, 0.218664167, 0.217179432, 0.215705789, 0.214243158, 0.212791454, 0.211350598, 0.209920507, 0.208501103, 0.207092304, 0.205694032, 0.204306207, 0.202928752, 0.201561587, 0.200204635, 0.19885782, 0.197521065, 0.196194293, 0.19487743, 0.193570399, 0.192273127, 0.19098554, 0.189707563, 0.188439124, 0.187180149, 0.185930567, 0.184690306, 0.183459294, 0.182237461, 0.181024737, 0.179821051, 0.178626335, 0.177440519, 0.176263535, 0.175095315, 0.173935792, 0.172784898, 0.171642567, 0.170508733, 0.16938333, 0.168266293, 0.167157558, 0.166057059, 0.164964734, 0.163880519, 0.162804351, 0.161736168, 0.160675908, 0.159623508, 0.158578909, 0.157542048, 0.156512867, 0.155491306, 0.154477304, 0.153470803, 0.152471745, 0.151480071, 0.150495724, 0.149518647, 0.148548783, 0.147586076, 0.146630469, 0.145681907, 0.144740336, 0.143805699, 0.142877944, 0.141957016, 0.141042862, 0.140135428, 0.139234663, 0.138340513, 0.137452928, 0.136571854, 0.135697243, 0.134829041, 0.133967201, 0.133111671, 0.132262402, 0.131419345, 0.130582451, 0.129751671, 0.128926959, 0.128108265, 0.127295544, 0.126488747, 0.125687829, 0.124892743, 0.124103444, 0.123319885, 0.122542022, 0.121769811, 0.121003206, 0.120242164, 0.119486641, 0.118736594, 0.117991979, 0.117252754, 0.116518877, 0.115790306, 0.115066999, 0.114348914, 0.113636011, 0.112928249, 0.112225587, 0.111527986, 0.110835406, 0.110147807, 0.109465151, 0.108787398, 0.108114511, 0.10744645, 0.106783179, 0.106124659, 0.105470853, 0.104821725, 0.104177238, 0.103537355, 0.10290204, 0.102271258, 0.101644973, 0.10102315, 0.100405754, 0.09979275, 0.099184104, 0.098579782, 0.09797975, 0.097383975, 0.096792423, 0.096205061, 0.095621857, 0.095042778, 0.094467792, 0.093896867, 0.093329972, 0.092767075, 0.092208144, 0.091653149, 0.09110206, 0.090554845, 0.090011475, 0.08947192, 0.088936151, 0.088404136, 0.087875849, 0.087351259, 0.086830338};

AudioInputI2S i2s1; //xy=204.00000381469727,247.00000381469727
AudioMixer4 mixer1; //xy=402,248
AudioAnalyzeFFT1024 fft1024_1; //xy=635.0000076293945,249.00000381469727
AudioConnection patchCord1(i2s1, 0, mixer1, 0);
AudioConnection patchCord2(i2s1, 1, mixer1, 1);
AudioConnection patchCord3(mixer1, fft1024_1);
// GUItool: end automatically generated code

AudioControlWM8960 wm8960;

const int myInput = AUDIO_INPUT_LINEIN;

void setup() {
analogReadResolution(16);
AudioMemory(60);
Serial.begin(9600);
fft1024_1.windowFunction(AudioWindowHanning1024);

wm8960.enable();
wm8960.inputSelect(myInput);
wm8960.volume(0.5);
}

void loop() {
if (fft1024_1.available()) {
magnitude = 0;
dB_holder = 0;
float v[512] = {0};

for (i=0; i<512; i++) {
v[i] = fft1024_1.read(i) * a_weight[i];
magnitude = magnitude + sq(v[i]);
}
magnitude = sqrt(magnitude);

dB_holder = log10f(magnitude) * 20 + 97.05;
Serial.println(dB_holder,2); // f[23] = 1kHz, f[82] = 3.5kHz, f[252] = 12kHz
}
}

The value of dB is presented.

The Decibel Meter Demo‚Äč

This example detects dB using the mic on ReSpeaker 2-Mic Hat, The around evirnment is detected, then displayed on the display.

Complete Code‚Äč


#include <Audio.h>
#include <Wire.h>
#include <SD.h>
#include <TFT_eSPI.h> // Hardware-specific library
#include <SPI.h>
#include <Bounce.h>
#include"seeed_line_chart.h" //include the library
TFT_eSPI tft = TFT_eSPI(); // Invoke custom library
#define TFT_GREY 0x5AEB
#define LOOP_PERIOD 35 // Display updates every 35 ms

#define max_size 20 //maximum size of data
doubles data; //Initilising a doubles type to store data
TFT_eSprite spr = TFT_eSprite(&tft); // Sprite
TFT_eSprite spr2 = TFT_eSprite(&tft);

float ltx = 0; // Saved x coord of bottom of needle
uint16_t osx = 120, osy = 120; // Saved x & y coords
uint32_t updateTime = 0; // time for next update

int old_analog = -999; // Value last displayed

int mode = 0; // 1=display_information

int i;
float v[512] = {0};
float magnitude = 0;
float dB_holder;
float a_weight[512] = {0.000491601, 0.007439144, 0.026456683, 0.057237193, 0.097648235, 0.145530499, 0.19895028, 0.256192702, 0.315753433, 0.376341431, 0.436880336, 0.496502258, 0.554533348, 0.610473237, 0.663971116, 0.714800959, 0.762837753, 0.808035908, 0.85041046, 0.890021233, 0.926959868, 0.961339445, 0.993286373, 1.022934171, 1.050418819, 1.075875354, 1.099435459, 1.12122582, 1.141367062, 1.159973138, 1.177151032, 1.193000704, 1.207615207, 1.221080906, 1.233477786, 1.244879798, 1.255355228, 1.264967081, 1.273773452, 1.281827897, 1.289179783, 1.29587462, 1.301954369, 1.307457742, 1.312420463, 1.316875521, 1.320853401, 1.324382291, 1.327488281, 1.330195534, 1.332526449, 1.334501812, 1.336140927, 1.337461742, 1.338480956, 1.339214128, 1.339675764, 1.339879407, 1.33983771, 1.33956251, 1.339064892, 1.338355246, 1.337443324, 1.336338287, 1.33504875, 1.333582824, 1.331948154, 1.330151954, 1.328201037, 1.326101843, 1.323860472, 1.3214827, 1.318974007, 1.316339599, 1.313584419, 1.310713175, 1.307730349, 1.304640214, 1.301446848, 1.298154147, 1.294765835, 1.291285478, 1.28771649, 1.284062146, 1.280325589, 1.276509835, 1.272617788, 1.268652238, 1.264615874, 1.260511287, 1.256340974, 1.252107348, 1.247812737, 1.243459393, 1.239049492, 1.234585143, 1.230068386, 1.2255012, 1.220885501, 1.216223152, 1.211515958, 1.206765674, 1.201974005, 1.19714261, 1.1922731, 1.187367045, 1.182425973, 1.177451372, 1.172444693, 1.167407348, 1.162340715, 1.157246139, 1.152124932, 1.146978373, 1.141807712, 1.136614169, 1.131398936, 1.126163178, 1.120908033, 1.115634612, 1.110344003, 1.105037268, 1.099715447, 1.094379556, 1.08903059, 1.083669521, 1.078297301, 1.072914859, 1.067523108, 1.062122937, 1.05671522, 1.05130081, 1.045880542, 1.040455233, 1.035025683, 1.029592675, 1.024156975, 1.018719333, 1.013280482, 1.00784114, 1.00240201, 0.996963778, 0.991527118, 0.986092686, 0.980661126, 0.975233068, 0.969809127, 0.964389904, 0.958975988, 0.953567954, 0.948166364, 0.942771769, 0.937384705, 0.932005696, 0.926635255, 0.921273883, 0.915922069, 0.91058029, 0.905249011, 0.899928687, 0.894619763, 0.88932267, 0.88403783, 0.878765656, 0.873506548, 0.868260896, 0.863029082, 0.857811477, 0.852608441, 0.847420326, 0.842247473, 0.837090216, 0.831948877, 0.826823771, 0.821715204, 0.816623471, 0.811548862, 0.806491654, 0.80145212, 0.796430522, 0.791427115, 0.786442146, 0.781475853, 0.776528467, 0.771600212, 0.766691304, 0.761801951, 0.756932355, 0.752082709, 0.747253202, 0.742444013, 0.737655316, 0.732887277, 0.728140056, 0.723413808, 0.71870868, 0.714024813, 0.709362343, 0.704721397, 0.700102099, 0.695504567, 0.690928912, 0.686375241, 0.681843653, 0.677334244, 0.672847104, 0.668382317, 0.663939963, 0.659520116, 0.655122846, 0.650748219, 0.646396293, 0.642067124, 0.637760764, 0.633477258, 0.629216649, 0.624978975, 0.620764269, 0.616572561, 0.612403877, 0.608258238, 0.604135661, 0.600036161, 0.595959749, 0.59190643, 0.587876209, 0.583869084, 0.579885053, 0.575924108, 0.571986239, 0.568071433, 0.564179674, 0.560310942, 0.556465216, 0.552642469, 0.548842674, 0.5450658, 0.541311815, 0.537580682, 0.533872363, 0.530186816, 0.526524, 0.522883867, 0.519266371, 0.51567146, 0.512099084, 0.508549187, 0.505021714, 0.501516605, 0.498033801, 0.49457324, 0.491134857, 0.487718587, 0.484324362, 0.480952113, 0.47760177, 0.47427326, 0.47096651, 0.467681443, 0.464417985, 0.461176056, 0.457955577, 0.454756467, 0.451578645, 0.448422028, 0.445286531, 0.442172069, 0.439078556, 0.436005904, 0.432954025, 0.429922829, 0.426912226, 0.423922125, 0.420952434, 0.41800306, 0.41507391, 0.412164889, 0.409275902, 0.406406853, 0.403557647, 0.400728185, 0.397918372, 0.395128108, 0.392357295, 0.389605834, 0.386873625, 0.384160569, 0.381466565, 0.378791512, 0.37613531, 0.373497856, 0.37087905, 0.368278789, 0.36569697, 0.363133492, 0.360588252, 0.358061147, 0.355552074, 0.353060929, 0.35058761, 0.348132012, 0.345694033, 0.343273569, 0.340870517, 0.338484772, 0.336116231, 0.333764791, 0.331430348, 0.329112798, 0.326812038, 0.324527964, 0.322260474, 0.320009464, 0.31777483, 0.315556471, 0.313354282, 0.311168162, 0.308998008, 0.306843717, 0.304705188, 0.302582319, 0.300475007, 0.298383152, 0.296306653, 0.294245408, 0.292199316, 0.290168278, 0.288152193, 0.286150961, 0.284164484, 0.28219266, 0.280235393, 0.278292582, 0.276364131, 0.27444994, 0.272549913, 0.270663953, 0.268791961, 0.266933843, 0.265089501, 0.263258841, 0.261441767, 0.259638183, 0.257847996, 0.256071111, 0.254307435, 0.252556875, 0.250819337, 0.249094729, 0.247382959, 0.245683935, 0.243997567, 0.242323763, 0.240662434, 0.239013489, 0.23737684, 0.235752397, 0.234140071, 0.232539776, 0.230951422, 0.229374924, 0.227810195, 0.226257148, 0.224715697, 0.223185759, 0.221667247, 0.220160077, 0.218664167, 0.217179432, 0.215705789, 0.214243158, 0.212791454, 0.211350598, 0.209920507, 0.208501103, 0.207092304, 0.205694032, 0.204306207, 0.202928752, 0.201561587, 0.200204635, 0.19885782, 0.197521065, 0.196194293, 0.19487743, 0.193570399, 0.192273127, 0.19098554, 0.189707563, 0.188439124, 0.187180149, 0.185930567, 0.184690306, 0.183459294, 0.182237461, 0.181024737, 0.179821051, 0.178626335, 0.177440519, 0.176263535, 0.175095315, 0.173935792, 0.172784898, 0.171642567, 0.170508733, 0.16938333, 0.168266293, 0.167157558, 0.166057059, 0.164964734, 0.163880519, 0.162804351, 0.161736168, 0.160675908, 0.159623508, 0.158578909, 0.157542048, 0.156512867, 0.155491306, 0.154477304, 0.153470803, 0.152471745, 0.151480071, 0.150495724, 0.149518647, 0.148548783, 0.147586076, 0.146630469, 0.145681907, 0.144740336, 0.143805699, 0.142877944, 0.141957016, 0.141042862, 0.140135428, 0.139234663, 0.138340513, 0.137452928, 0.136571854, 0.135697243, 0.134829041, 0.133967201, 0.133111671, 0.132262402, 0.131419345, 0.130582451, 0.129751671, 0.128926959, 0.128108265, 0.127295544, 0.126488747, 0.125687829, 0.124892743, 0.124103444, 0.123319885, 0.122542022, 0.121769811, 0.121003206, 0.120242164, 0.119486641, 0.118736594, 0.117991979, 0.117252754, 0.116518877, 0.115790306, 0.115066999, 0.114348914, 0.113636011, 0.112928249, 0.112225587, 0.111527986, 0.110835406, 0.110147807, 0.109465151, 0.108787398, 0.108114511, 0.10744645, 0.106783179, 0.106124659, 0.105470853, 0.104821725, 0.104177238, 0.103537355, 0.10290204, 0.102271258, 0.101644973, 0.10102315, 0.100405754, 0.09979275, 0.099184104, 0.098579782, 0.09797975, 0.097383975, 0.096792423, 0.096205061, 0.095621857, 0.095042778, 0.094467792, 0.093896867, 0.093329972, 0.092767075, 0.092208144, 0.091653149, 0.09110206, 0.090554845, 0.090011475, 0.08947192, 0.088936151, 0.088404136, 0.087875849, 0.087351259, 0.086830338};
float init_value = 95.05;

AudioInputI2S i2s1; //xy=204.00000381469727,247.00000381469727
AudioMixer4 mixer1; //xy=402,248
AudioAnalyzeFFT1024 fft1024_1; //xy=635.0000076293945,249.00000381469727
AudioConnection patchCord1(i2s1, 0, mixer1, 0);
AudioConnection patchCord2(i2s1, 1, mixer1, 1);
AudioConnection patchCord3(mixer1, fft1024_1);
// GUItool: end automatically generated code

AudioControlWM8960 wm8960;

// which input on the audio shield will be used?
#ifndef SEEED_WIO_TERMINAL
const int myInput = AUDIO_INPUT_LINEIN;
#else
const int myInput = AUDIO_INPUT_MIC;
#endif

void setup(void) {
tft.init();
tft.setRotation(0);
Serial.begin(57600); // For debug
spr.createSprite(240,160);
tft.fillScreen(TFT_WHITE);
tft.setTextColor(TFT_BLACK, TFT_RED);
tft.setFreeFont(&FreeSansBoldOblique9pt7b);
tft.drawString("dB value guidance", 40, 40);
tft.setTextColor(TFT_BLACK, TFT_YELLOW);
tft.setFreeFont(&FreeSansBoldOblique9pt7b);
tft.drawString("0 - 25 dB Whisper", 20, 80);
tft.drawString("25 - 50 dB Quite library", 20, 110);
tft.drawString("50 - 75 dB Loud Music", 20, 140);
tft.drawString("75 - 100 dB Motorcycle", 20, 170);
delay(5000);
tft.fillScreen(TFT_WHITE);

analogMeter(); // Draw analogue meter

updateTime = millis(); // Next update time

analogReadResolution(16);

AudioMemory(60);

fft1024_1.windowFunction(AudioWindowHanning1024);

wm8960.enable();
wm8960.inputSelect(myInput);


}

void loop() {

if (fft1024_1.available()) {
magnitude = 0;
dB_holder = 0;
float v[512] = {0};

for (i=0; i<512; i++) {
v[i] = fft1024_1.read(i) * a_weight[i];
magnitude = magnitude + sq(v[i]);
}
magnitude = sqrt(magnitude);
dB_holder = log10f(magnitude) * 20 + init_value;

}
Serial.println(dB_holder); // f[23] = 1kHz, f[82] = 3.5kHz, f[252] = 12kHz

// #########################################################################
// dispaly the line charts
// #########################################################################
spr.fillSprite(TFT_WHITE);
if (data.size() == max_size) {
data.pop();//this is used to remove the first read variable
}
data.push(dB_holder); //read variables and store in data

spr2.createSprite(40, 40);
spr2.fillSprite(TFT_WHITE);
spr2.setTextColor(TFT_BLACK, TFT_WHITE);
spr2.setFreeFont(&FreeSansBoldOblique18pt7b);
//char buf_2[0]; dtostrf(dB_holder, 2, 1, buf_2);
spr2.drawNumber(dB_holder, 0, 0);
spr2.pushSprite(80, 140);
spr2.deleteSprite();

//Settings for the line graph title
auto header = text(7, 0)
.value("dB")
.valign(vcenter)
.width(tft.width())
.thickness(2);

header.height(header.font_height() * 1.1);
header.draw(); //Header height is the twice the height of the font

//Settings for the line graph
auto content = line_chart(8, header.height()); //(x,y) where the line graph begins
content
.height(tft.height() - header.height() * 12) //actual height of the line chart
.width(tft.width() - content.x() * 2) //actual width of the line chart
.based_on(0.0) //Starting point of y-axis, must be a float
.show_circle(true) //drawing a cirle at each point, default is on.
.value(data) //passing through the data to line graph
.color(TFT_PURPLE) //Setting the color for the line
.draw();

spr.pushSprite(0, 190);
delay(50);

// #########################################################################

if (updateTime <= millis()) {
updateTime = millis() + LOOP_PERIOD;
int d;
d += 4;
if (d >= 360) {
d = 0;
}
plotNeedle(dB_holder, 0);
}
}

// #########################################################################
// Draw the analogue meter on the screen
// #########################################################################
void analogMeter() {
// Meter outline
tft.fillRect(0, 0, 239, 126, TFT_GREY);
tft.fillRect(5, 3, 230, 119, TFT_WHITE);
tft.setTextColor(TFT_BLACK); // Text colour

// Draw ticks every 5 degrees from -50 to +50 degrees (100 deg. FSD swing)
for (int i = -50; i < 51; i += 5) {
// Long scale tick length
int tl = 15;

// Coodinates of tick to draw
float sx = cos((i - 90) * 0.0174532925);
float sy = sin((i - 90) * 0.0174532925);
uint16_t x0 = sx * (100 + tl) + 120;
uint16_t y0 = sy * (100 + tl) + 140;
uint16_t x1 = sx * 100 + 120;
uint16_t y1 = sy * 100 + 140;

// Coordinates of next tick for zone fill
float sx2 = cos((i + 5 - 90) * 0.0174532925);
float sy2 = sin((i + 5 - 90) * 0.0174532925);
int x2 = sx2 * (100 + tl) + 120;
int y2 = sy2 * (100 + tl) + 140;
int x3 = sx2 * 100 + 120;
int y3 = sy2 * 100 + 140;

// Yellow zone limits
if (i >= -50 && i < 0) {
tft.fillTriangle(x0, y0, x1, y1, x2, y2, TFT_GREEN);
tft.fillTriangle(x1, y1, x2, y2, x3, y3, TFT_GREEN);
}

// Green zone limits
if (i >= 0 && i < 25) {
tft.fillTriangle(x0, y0, x1, y1, x2, y2, TFT_YELLOW);
tft.fillTriangle(x1, y1, x2, y2, x3, y3, TFT_YELLOW);
}

// Orange zone limits
if (i >= 25 && i < 50) {
tft.fillTriangle(x0, y0, x1, y1, x2, y2, TFT_RED);
tft.fillTriangle(x1, y1, x2, y2, x3, y3, TFT_RED);
}

// Short scale tick length
if (i % 25 != 0) {
tl = 8;
}

// Recalculate coords incase tick lenght changed
x0 = sx * (100 + tl) + 120;
y0 = sy * (100 + tl) + 140;
x1 = sx * 100 + 120;
y1 = sy * 100 + 140;

// Draw tick
tft.drawLine(x0, y0, x1, y1, TFT_BLACK);

// Check if labels should be drawn, with position tweaks
if (i % 25 == 0) {
// Calculate label positions
x0 = sx * (100 + tl + 10) + 120;
y0 = sy * (100 + tl + 10) + 140;
switch (i / 25) {
case -2: tft.drawCentreString("0", x0, y0 - 12, 2); break;
case -1: tft.drawCentreString("25", x0, y0 - 9, 2); break;
case 0: tft.drawCentreString("50", x0, y0 - 6, 2); break;
case 1: tft.drawCentreString("75", x0, y0 - 9, 2); break;
case 2: tft.drawCentreString("100", x0, y0 - 12, 2); break;
}
}

// Now draw the arc of the scale
sx = cos((i + 5 - 90) * 0.0174532925);
sy = sin((i + 5 - 90) * 0.0174532925);
x0 = sx * 100 + 120;
y0 = sy * 100 + 140;
// Draw scale arc, don't draw the last part
if (i < 50) {
tft.drawLine(x0, y0, x1, y1, TFT_BLACK);
}
}

//tft.drawString("dB", 5 + 230 - 40, 119 - 20, 2); // Units at bottom right
tft.drawCentreString("dB", 120, 80, 4); // Comment out to avoid font 4
tft.drawRect(5, 3, 230, 119, TFT_BLACK); // Draw bezel line

tft.setTextColor(TFT_BLACK, TFT_WHITE);
tft.setFreeFont(&FreeSansBoldOblique18pt7b);
tft.drawString(" dB",120,140);

plotNeedle(0, 0); // Put meter needle at 0
}



// #########################################################################
// Update needle position
// This function is blocking while needle moves, time depends on ms_delay
// 10ms minimises needle flicker if text is drawn within needle sweep area
// Smaller values OK if text not in sweep area, zero for instant movement but
// does not look realistic... (note: 100 increments for full scale deflection)
// #########################################################################
void plotNeedle(int value, byte ms_delay) {
if (value < -10) {
value = -10; // Limit value to emulate needle end stops
}
if (value > 110) {
value = 110;
}

// Move the needle util new value reached
while (!(value == old_analog)) {
if (old_analog < value) {
old_analog++;
} else {
old_analog--;
}

if (ms_delay == 0) {
old_analog = value; // Update immediately id delay is 0
}

float sdeg = map(old_analog, -10, 110, -150, -30); // Map value to angle
// Calcualte tip of needle coords
float sx = cos(sdeg * 0.0174532925);
float sy = sin(sdeg * 0.0174532925);

// Calculate x delta of needle start (does not start at pivot point)
float tx = tan((sdeg + 90) * 0.0174532925);

// Erase old needle image
tft.drawLine(120 + 20 * ltx - 1, 140 - 20, osx - 1, osy, TFT_WHITE);
tft.drawLine(120 + 20 * ltx, 140 - 20, osx, osy, TFT_WHITE);
tft.drawLine(120 + 20 * ltx + 1, 140 - 20, osx + 1, osy, TFT_WHITE);

// Re-plot text under needle
tft.setTextColor(TFT_BLACK);
tft.drawCentreString("dB", 120, 80, 4); // // Comment out to avoid font 4

// Store new needle end coords for next erase
ltx = tx;
osx = sx * 98 + 120;
osy = sy * 98 + 140;

// Draw the needle in the new postion, magenta makes needle a bit bolder
// draws 3 lines to thicken needle
tft.drawLine(120 + 20 * ltx - 1, 140 - 20, osx - 1, osy, TFT_RED);
tft.drawLine(120 + 20 * ltx, 140 - 20, osx, osy, TFT_MAGENTA);
tft.drawLine(120 + 20 * ltx + 1, 140 - 20, osx + 1, osy, TFT_RED);

// Slow needle down slightly as it approaches new postion
if (abs(old_analog - value) < 10) {
ms_delay += ms_delay / 5;
}
// Wait before next update
delay(ms_delay);
}
}

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