66 lines
1.9 KiB
C++
66 lines
1.9 KiB
C++
// This file is part of Necroware's GamePort adapter firmware.
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// Copyright (C) 2021 Necroware
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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#pragma once
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#include <Arduino.h>
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/// Class to read analog axis.
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///
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/// Usually PC joystick axes are specified to have 100 Ohm resistance, but
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/// many analog joysticks have old, bad, or just wrong resistors. This ends
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/// up in incorrect positions and is especially bad for games, which don't
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/// have calibration features. This class takes care of this issue and
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/// applies automatic calibration on every read.
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template <int ID>
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class AnalogAxis {
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public:
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/// Constructor.
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///
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/// The initial state of the joystick is considered as middle
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/// which is used for autocalibration.
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AnalogAxis() {
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pinMode(ID, INPUT);
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m_mid = analogRead(ID);
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m_min = m_mid - 100;
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m_max = m_mid + 100;
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}
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/// Gets the axis state.
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///
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/// This function automatically recalculates the outer limits and
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/// readjusts the position of the joystick.
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/// @returns a value between 0 and 1023
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uint16_t get() {
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const auto value = analogRead(ID);
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if (value < m_min) {
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m_min = value;
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} else if (value > m_max) {
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m_max = value;
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}
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if (value < m_mid) {
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return map(value, m_min, m_mid, 1023, 512);
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}
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return map(value, m_mid, m_max, 511, 0);
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}
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private:
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int m_mid;
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int m_min;
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int m_max;
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};
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