AnalogBurst.ino

Captures 500 samples of A0 at 20000 samples per second with analogReadBurst(), plots them in the Serial Plotter and prints the rate, lowest, highest and mean. The hardware takes the samples at evenly spaced times, so the plot shows the true waveform.

Wiring

A wire from D2 to A0: the sketch plays a 500 Hz test tone on D2. Or a signal generator on A0 (0-3.3 V), and remove the tone() line.

Output

Tools → Serial Plotter at 115200 baud: a square wave, then a line such as

Rate 20000 Hz, lowest 3, highest 4093, mean 2049

Notes

Highest rates: A0-A2 500000 samples/s, A3-A5 300000 samples/s. Change PIN, RATE_HZ and SAMPLES at the top of the sketch.

// Captures a waveform: 500 samples at a fixed rate, taken by the hardware at
// evenly spaced times, then plotted in the Serial Plotter (Tools > Serial
// Plotter, 115200 baud). Prints the sample rate, lowest, highest and mean too.
//
// Try it with a signal generator, or with tone(2, 500) and a wire from D2 to
// A0 (D2 is 0-3.3 V, so use A0-A2 for it, not A3-A5).
//
// Highest rates: A0-A2 500000 samples/s, A3-A5 300000 samples/s.
 
const pin_size_t PIN = A0;
const uint32_t RATE_HZ = 20000;  // samples per second
const size_t SAMPLES = 500;
 
uint16_t samples[SAMPLES];
 
void setup() {
    Serial.begin(115200);
    while (!Serial) {}
    analogReadResolution(12);
    tone(2, 500);  // test signal on D2; remove if you use your own
}
 
void loop() {
    const uint32_t rate = analogReadBurst(PIN, samples, SAMPLES, RATE_HZ);
    if (rate == 0) {
        Serial.println("Burst refused: check PIN and RATE_HZ");
        delay(2000);
        return;
    }
 
    uint16_t lowest = 4095;
    uint16_t highest = 0;
    uint32_t sum = 0;
    for (size_t i = 0; i < SAMPLES; i++) {
        if (samples[i] < lowest) lowest = samples[i];
        if (samples[i] > highest) highest = samples[i];
        sum += samples[i];
        Serial.print("Signal:");
        Serial.println(samples[i]);
    }
 
    Serial.print("Rate ");
    Serial.print(rate);
    Serial.print(" Hz, lowest ");
    Serial.print(lowest);
    Serial.print(", highest ");
    Serial.print(highest);
    Serial.print(", mean ");
    Serial.println(sum / SAMPLES);
    delay(2000);
}