// Filtered joystick read and report.

union {
    uint32_t accum;
    struct {
	uint16_t lower;
	uint16_t upper;
    } words;
} potval_X, potval_Y;;

unsigned long oldmillis;

void setup() {
    Serial.begin(115200);
    oldmillis = millis();
}

#define WEIGHT 64 // Must be power of two.
#define FREQ 1000 // Millis between reports when no change.

void loop() {
    uint32_t X_Value = (uint32_t)analogRead(A0) << 16;
    uint32_t Y_Value = (uint32_t)analogRead(A1) << 16;
    uint16_t oldval_X = potval_X.words.upper;
    uint16_t oldval_Y = potval_Y.words.upper;
    
    potval_X.accum =
	((WEIGHT - 1) * potval_X.accum + X_Value + 32768) / WEIGHT;
    potval_Y.accum =
	((WEIGHT - 1) * potval_Y.accum + Y_Value + 32768) / WEIGHT;


    unsigned long newmillis = millis();
    if (potval_X.words.upper != oldval_X ||
    potval_Y.words.upper != oldval_Y ||
    newmillis - oldmillis >= FREQ) {
        oldmillis = newmillis;
	Serial.write(':');
	Serial.print(potval_X.words.upper);
	Serial.write(' ');
	Serial.print(potval_Y.words.upper);
	Serial.write(10);
    }
}