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@@ -1,5 +1,5 @@
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/*
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- * clockworkpi devterm trackball
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+ * ClockworkPi DevTerm Trackball
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*/
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#include "keys_io_map.h"
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@@ -9,122 +9,213 @@
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#include <USBComposite.h>
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-
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#include "trackball.h"
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-
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-#include "ratemeter.h"
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-#include "glider.h"
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#include "math.h"
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-
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-
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-enum Axis: uint8_t {
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- AXIS_X,
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- AXIS_Y,
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- AXIS_NUM,
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+// Choose the type of filter (add a `_` to the #define you're not using):
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+// - FIR uses more memory and takes longer to run, but you can tweak the FILTER_SIZE
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+// - IIR is faster (has less coefficients), but the coefficients are pre-calculated (via scipy)
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+#define _USE_FIR
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+#define USE_IIR
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+
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+// Enable debug messages via serial
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+#define _DEBUG_TRACKBALL
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+
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+// Source: https://github.com/dangpzanco/dsp
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+#include <dsp_filters.h>
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+
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+// Simple trackball pin direction counter
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+enum TrackballPin : uint8_t
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+{
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+ PIN_LEFT,
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+ PIN_RIGHT,
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+ PIN_UP,
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+ PIN_DOWN,
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+ PIN_NUM,
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};
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-static TrackballMode lastMode;
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-static int8_t distances[AXIS_NUM];
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-static RateMeter rateMeter[AXIS_NUM];
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-static Glider glider[AXIS_NUM];
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-
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-static const int8_t WHEEL_DENOM = 2;
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-static int8_t wheelBuffer;
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-
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-static float rateToVelocityCurve(float input) {
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- //return std::pow(std::abs(input) / 50, 1.4);
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- return std::abs(input) / 30;
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-}
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-
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-template<Axis AXIS, int8_t Direction >
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-static void interrupt( ) {
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- distances[AXIS] += Direction;
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- rateMeter[AXIS].onInterrupt();
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- glider[AXIS].setDirection(Direction);
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-
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- const auto rx = rateMeter[AXIS_X].rate();
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- const auto ry = rateMeter[AXIS_Y].rate();
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-
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- const auto rate = std::sqrt(rx * rx + ry * ry);
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- const auto ratio = rateToVelocityCurve(rate) / rate;
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-
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- const auto vx = rx * ratio;
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- const auto vy = ry * ratio;
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-
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- if (AXIS == AXIS_X) {
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- glider[AXIS_X].update(vx, std::sqrt(rateMeter[AXIS_X].delta()));
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- glider[AXIS_Y].updateSpeed(vy);
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-
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- } else {
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- glider[AXIS_X].updateSpeed(vx);
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- glider[AXIS_Y].update(vy, std::sqrt(rateMeter[AXIS_Y].delta()));
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-
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- }
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-
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-
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+static uint8_t direction_counter[PIN_NUM] = {0};
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+
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+// Mouse and Wheel sensitivity values
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+static const float MOUSE_SENSITIVITY = 10.0f;
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+static const float WHEEL_SENSITIVITY = 0.25f;
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+
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+#ifdef USE_IIR
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+// Infinite Impulse Response (IIR) Filter
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+// Filter design (https://docs.scipy.org/doc/scipy/reference/signal.html):
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+// Low-pass Butterworth filter [b, a = scipy.signal.butter(N=2, Wn=0.1)]
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+static const int8_t IIR_SIZE = 3;
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+static float iir_coeffs_b[IIR_SIZE] = {0.020083365564211232, 0.040166731128422464, 0.020083365564211232};
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+static float iir_coeffs_a[IIR_SIZE] = {1.0, -1.5610180758007182, 0.6413515380575631};
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+IIR iir_x, iir_y;
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+#endif
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+
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+#ifdef USE_FIR
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+// FIR Filter
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+static const int8_t FILTER_SIZE = 10;
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+static float fir_coeffs[FILTER_SIZE];
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+FIR fir_x, fir_y;
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+
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+static void init_fir()
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+{
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+ // Moving Average Finite Impulse Response (FIR) Filter:
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+ // - Smooths out corners (the trackball normally only moves in 90 degree angles)
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+ // - Filters out noisy data (avoids glitchy movements)
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+ // - Adds delay to the movement. To tweak this:
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+ // 1. Change the FILTER_SIZE (delay is proportional to the size, use millis() to measure time)
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+ // 2. Redesign the filter with the desired delay
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+ for (int8_t i = 0; i < FILTER_SIZE; i++)
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+ fir_coeffs[i] = 1.0f / FILTER_SIZE;
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}
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-
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-void trackball_task(DEVTERM*dv) {
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- int8_t x = 0, y = 0, w = 0;
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- noInterrupts();
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- const auto mode = dv->state->moveTrackball();
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- if (lastMode != mode) {
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- rateMeter[AXIS_X].expire();
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- rateMeter[AXIS_Y].expire();
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- wheelBuffer = 0;
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- }
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- else {
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- rateMeter[AXIS_X].tick(dv->delta);
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- rateMeter[AXIS_Y].tick(dv->delta);
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- }
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- lastMode = mode;
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-
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- switch(mode){
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- case TrackballMode::Mouse: {
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- const auto rX = glider[AXIS_X].glide(dv->delta);
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- const auto rY = glider[AXIS_Y].glide(dv->delta);
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- x = rX.value;
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- y = rY.value;
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- if (rX.stopped) {
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- glider[AXIS_Y].stop();
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- }
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- if (rY.stopped) {
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- glider[AXIS_Y].stop();
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- }
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-
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- break;
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+#endif
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+
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+#ifdef DEBUG_TRACKBALL
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+static uint32_t time = millis();
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+
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+// Useful debug function
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+template <typename T>
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+void print_vec(DEVTERM *dv, T *vec, uint32_t size, bool newline = true)
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+{
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+ for (int8_t i = 0; i < size - 1; i++)
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+ {
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+ dv->_Serial->print(vec[i]);
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+ dv->_Serial->print(",");
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}
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- case TrackballMode::Wheel: {
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- wheelBuffer += distances[AXIS_Y];
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- w = wheelBuffer / WHEEL_DENOM;
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- wheelBuffer -= w * WHEEL_DENOM;
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- if(w != 0){
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- dv->state->setScrolled();
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- }
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- break;
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+ if (newline)
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+ {
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+ dv->_Serial->println(vec[size - 1]);
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}
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- }
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- distances[AXIS_X] = 0;
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- distances[AXIS_Y] = 0;
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- interrupts();
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-
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- if(x !=0 || y != 0 || -w!=0) {
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- dv->Mouse->move(x, y, -w);
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- }
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-
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+ else
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+ {
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+ dv->_Serial->print(vec[size - 1]);
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+ dv->_Serial->print(",");
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+ }
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+}
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+#endif
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+
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+template <TrackballPin PIN>
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+static void interrupt()
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+{
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+ // Count the number of times the trackball rolls towards a certain direction
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+ // (when the corresponding PIN changes its value). This part of the code should be minimal,
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+ // so that the next interrupts are not blocked from happening.
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+ direction_counter[PIN] += 1;
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}
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+static float position_scale(float x)
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+{
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+ // Exponential scaling of the mouse movement:
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+ // - Small values remain small (precise movement)
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+ // - Slightly larger values get much larger (fast movement)
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+ // This function may be tweaked further, but it's good enough for now.
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+ return MOUSE_SENSITIVITY * sign(x) * std::exp(std::abs(x) / std::sqrt(MOUSE_SENSITIVITY));
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+}
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-void trackball_init(DEVTERM*dv){
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+void trackball_task(DEVTERM *dv)
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+{
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+
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+#ifdef DEBUG_TRACKBALL
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+ // Measure elapsed time
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+ uint32_t elapsed = millis() - time;
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+ time += elapsed;
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+
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+ // Send raw data via serial (CSV format)
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+ dv->_Serial->print(elapsed);
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+ dv->_Serial->print(",");
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+ print_vec(dv, direction_counter, PIN_NUM);
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+#endif
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+
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+
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+ // Stop interrupts from happening. Don't forget to re-enable them!
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+ noInterrupts();
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+
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+ // Calculate x and y positions
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+ float x = direction_counter[PIN_RIGHT] - direction_counter[PIN_LEFT];
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+ float y = direction_counter[PIN_DOWN] - direction_counter[PIN_UP];
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+
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+ // Clear counters
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+ // memset(direction_counter, 0, sizeof(direction_counter));
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+ std::fill(std::begin(direction_counter), std::end(direction_counter), 0);
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+
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+ // Re-enable interrupts (Mouse.move needs interrupts)
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+ interrupts();
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+
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+ // Non-linear scaling
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+ x = position_scale(x);
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+ y = position_scale(y);
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+
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+ // Wheel rolls with the (reverse) vertical axis (no filter needed)
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+ int8_t w = clamp<int8_t>(-y * WHEEL_SENSITIVITY);
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+
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+ // Filter x and y
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+#ifdef USE_FIR
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+ x = fir_filt(&fir_x, x);
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+ y = fir_filt(&fir_y, y);
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+#endif
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+#ifdef USE_IIR
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+ x = iir_filt(&iir_x, x);
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+ y = iir_filt(&iir_y, y);
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+#endif
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+
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+ // Move Trackball (either Mouse or Wheel)
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+ switch (dv->state->moveTrackball())
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+ {
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+ case TrackballMode::Mouse:
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+ {
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+ // Move mouse
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+ while ((int)x != 0 || (int)y != 0)
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+ {
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+ // Only 8bit values are allowed,
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+ // so clamp and execute move() multiple times
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+ int8_t x_byte = clamp<int8_t>(x);
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+ int8_t y_byte = clamp<int8_t>(y);
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+
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+ // Move mouse with values in the range [-128, 127]
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+ dv->Mouse->move(x_byte, y_byte, 0);
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+
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+ // Decrement the original value, stop if done
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+ x -= x_byte;
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+ y -= y_byte;
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+ }
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+
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+ break;
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+ }
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+ case TrackballMode::Wheel:
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+ {
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+ if (w != 0)
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+ {
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+ // Only scroll the wheel [move cursor by (0,0)]
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+ dv->Mouse->move(0, 0, w);
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+ dv->state->setScrolled();
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+ }
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+
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+ break;
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+ }
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+ }
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+}
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- pinMode(LEFT_PIN, INPUT);
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- pinMode(UP_PIN, INPUT);
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- pinMode(RIGHT_PIN, INPUT);
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- pinMode(DOWN_PIN, INPUT);
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+void trackball_init(DEVTERM *dv)
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+{
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+ // Enable trackball pins
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+ pinMode(LEFT_PIN, INPUT);
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+ pinMode(UP_PIN, INPUT);
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+ pinMode(RIGHT_PIN, INPUT);
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+ pinMode(DOWN_PIN, INPUT);
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+
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+ // Initialize filters
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+#ifdef USE_FIR
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+ init_fir();
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+ fir_init(&fir_x, FILTER_SIZE, fir_coeffs);
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+ fir_init(&fir_y, FILTER_SIZE, fir_coeffs);
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+#endif
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+#ifdef USE_IIR
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+ iir_init(&iir_x, IIR_SIZE, iir_coeffs_b, IIR_SIZE, iir_coeffs_a);
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+ iir_init(&iir_y, IIR_SIZE, iir_coeffs_b, IIR_SIZE, iir_coeffs_a);
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+#endif
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+
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+ // Run interrupt function when corresponding PIN changes its value
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+ attachInterrupt(LEFT_PIN, &interrupt<PIN_LEFT>, ExtIntTriggerMode::CHANGE);
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+ attachInterrupt(RIGHT_PIN, &interrupt<PIN_RIGHT>, ExtIntTriggerMode::CHANGE);
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+ attachInterrupt(UP_PIN, &interrupt<PIN_UP>, ExtIntTriggerMode::CHANGE);
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+ attachInterrupt(DOWN_PIN, &interrupt<PIN_DOWN>, ExtIntTriggerMode::CHANGE);
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- attachInterrupt(LEFT_PIN, &interrupt<AXIS_X,-1> , ExtIntTriggerMode::CHANGE);
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- attachInterrupt(RIGHT_PIN, &interrupt<AXIS_X, 1>, ExtIntTriggerMode::CHANGE);
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- attachInterrupt(UP_PIN, &interrupt<AXIS_Y, -1>, ExtIntTriggerMode::CHANGE);
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- attachInterrupt(DOWN_PIN, &interrupt<AXIS_Y, 1>, ExtIntTriggerMode::CHANGE);
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-
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}
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