/*
【花雕动手做】音乐可视化系列小项目（02）---OLED频谱灯
项目之三：32段分频0.91寸OLED液晶可视化细条频谱灯
实验接线: max9814接A0
oled模块 Ardunio Uno
GND---------GND接地线
VCC---------5V 接电源
SDA---------A4
SCL ------- A5
*/
#include <fix_fft.h>
#include <ssd1306.h>
#include <nano_engine.h>
// These are user-adjustable
#define LOG_OUTPUT // Uncomment to enable logarithmic output (exchanges absolute resoluton for more readable output; may require different below params)
#define SAMPLING_FREQUENCY 15000 // Sampling frequency (Actual max measured frequency captured is half)
#define TIME_FACTOR 2 // Smoothing factor (lower is more dynamic, higher is smoother) ranging from 1 to 10+
#define SCALE_FACTOR 15 // Direct scaling factor (raise for higher bars, lower for shorter bars)
#ifdef LOG_OUTPUT
const float log_scale = 64. / log(64. / SCALE_FACTOR + 1.); // Attempts to create an equivalent to SCALE_FACTOR for log function
#endif
const float coeff = 1. / TIME_FACTOR; // Time smoothing coefficients (used to factor in previous data)
const float anti_coeff = (TIME_FACTOR - 1.) / TIME_FACTOR;
const unsigned int sampling_period_us = round(1000000 * (2.0 / SAMPLING_FREQUENCY)); // Sampling period (doubled to account for overclock)
int8_t data[64], buff[32]; // used to store FFT input/output and past data
unsigned long microseconds; // used for timekeeping
int summ, avg; // used for DC bias elimination
NanoEngine<TILE_32x32_MONO> engine; // declares nanoengine
void setup()
{
OSCCAL = 240; // Overclocks the MCU to around 30 MHz, set lower if this causes instability, raise if you can/want
ADCSRA &= ~(bit (ADPS0) | bit (ADPS1) | bit (ADPS2)); // clear ADC prescaler bits
ADCSRA |= bit (ADPS2); // sets ADC clock in excess of 10kHz
ADCSRA |= bit (ADPS0);
ssd1306_128x64_i2c_init(); // initializes OLED
ssd1306_clearScreen(); // clears OLED
engine.begin(); // inititalizes nanoengine
};
void loop()
{
summ = 0;
for (int i = 0; i < 64; i++) {
microseconds = micros();
data[i] = ((analogRead(A0)) >> 2) - 128; // Fitting analogRead data (range:0 - 1023) to int8_t array (range:-128 - 127)
summ += data[i];
while (micros() < (microseconds + sampling_period_us)) { // Timing out uC ADC to fulfill sampling frequency requirement
}
}
// Eliminating remaining DC component (produces usable data in FFT bin #0, which is usually swamped by DC bias)
avg = summ / 64;
for (int i = 0; i < 64; i++) {
data[i] -= avg;
}
fix_fftr(data, 6, 0); // Performing real FFT
// Time smoothing by user-determined factor and user-determined scaling
for (int count = 0; count < 32; count++) {
if (data[count] < 0) data[count] = 0; // Eliminating negative output of fix_fftr
#ifdef LOG_OUTPUT
else data[count] = log_scale * log((float)(data[count] + 1)); // Logarithmic function equivalent to SCALING_FACTOR*log2(x+1)
#else
else data[count] *= SCALE_FACTOR; // Linear scaling up according to SCALE_FACTOR
#endif
data[count] = (float)buff[count] * anti_coeff + (float)data[count] * coeff; // Smoothing by factoring in past data
buff[count] = data[count]; // Storing current output as next frame's past data
if (data[count] > 63) data[count] = 63; // Capping output at screen height
}
// Output to SSD1306 using nanoengine canvas from library
engine.refresh(); // Mark entire screen to be refreshed
engine.canvas.clear(); // Clear canvas as previous data
for (int i = 0; i < 8; i++) {
engine.canvas.drawVLine(i * 4, 31 - (data[i] + 1), 31); // Draw to canvas data for lower-leftest sector (FFT bins 0 - 7, lower half)
}
engine.canvas.blt(0, 32); // Outputs canvas to OLED with an offset (x pixels, y pixels)
engine.canvas.clear();
for (int i = 0; i < 8; i++) {
if (data[i] > 31) engine.canvas.drawVLine(i * 4, 31 - (data[i] - 31), 31); // Draw to canvas data for upper-leftest sector (FFT bins 0 - 7, upper half)
}
engine.canvas.blt(0, 0);
engine.canvas.clear();
for (int i = 8; i < 16; i++) {
engine.canvas.drawVLine((i - 8) * 4, 31 - (data[i] + 1), 31); // FFT bins 8 - 15, lower half
}
engine.canvas.blt(32, 32);
engine.canvas.clear();
for (int i = 8; i < 16; i++) {
if (data[i] > 31) engine.canvas.drawVLine((i - 8) * 4, 31 - (data[i] - 31), 31); // FFT bins 9 - 15, upper half
}
engine.canvas.blt(32, 0);
engine.canvas.clear();
for (int i = 16; i < 24; i++) {
engine.canvas.drawVLine((i - 16) * 4, 31 - (data[i] + 1), 31); // FFT bins 16 - 23, lower half
}
engine.canvas.blt(64, 32);
engine.canvas.clear();
for (int i = 16; i < 24; i++) {
if (data[i] > 31) engine.canvas.drawVLine((i - 16) * 4, 31 - (data[i] - 31), 31); // FFT bins 16 - 23, upper half
}
engine.canvas.blt(64, 0);
engine.canvas.clear();
for (int i = 24; i < 32; i++) {
engine.canvas.drawVLine((i - 24) * 4, 31 - (data[i] + 1), 31); // FFT bins 24 - 31, lower half
}
engine.canvas.blt(96, 32);
engine.canvas.clear();
for (int i = 24; i < 32; i++) {
if (data[i] > 31) engine.canvas.drawVLine((i - 24) * 4, 31 - (data[i] - 31), 31); // FFT bins 24 - 31, upper half
}
engine.canvas.blt(96, 0);
}
