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BinaryMan32BinaryMan32
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map potentiometer resistance to output range
Add independent mappings for each potentiometer so they can be calibrated based on measured resistances at the limits of the physical range of movement.
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6 files changed

+416
-54
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6 files changed

+416
-54
lines changed

‎examples/phoenix-arduino-test/phoenix-arduino-test.ino

Lines changed: 41 additions & 53 deletions
Original file line numberDiff line numberDiff line change
@@ -19,6 +19,7 @@
1919
* https://playground.arduino.cc/Code/ShiftRegSN74HC165N
2020
*/
2121
#include "hc165.h"
22+
#include "Potentiometer.h"
2223

2324
/* Optional delay between shift register reads.
2425
*/
@@ -52,55 +53,46 @@ hc165_collection_t hc165_collection = {
5253
.size = numButtonGroups,
5354
};
5455

56+
const size_t numAxes = 4;
57+
58+
const Potentiometer axesPotentiometers[numAxes] = {
59+
{Potentiometer::Parameters{
60+
.name = "X",
61+
.analogInputPin = A0,
62+
.referenceResistance = 100,
63+
.resistanceRange = {.min = 0, .max = 87},
64+
.outputRange = {.min = 0, .max = 127},
65+
}},
66+
{Potentiometer::Parameters{
67+
.name = "Y",
68+
.analogInputPin = A1,
69+
.referenceResistance = 100,
70+
.resistanceRange = {.min = 0, .max = 85},
71+
.outputRange = {.min = 0, .max = 127},
72+
}},
73+
{Potentiometer::Parameters{
74+
.name = "R",
75+
.analogInputPin = A4,
76+
.referenceResistance = 100,
77+
.resistanceRange = {.min = 0, .max = 94},
78+
.outputRange = {.min = 0, .max = 127},
79+
}},
80+
{Potentiometer::Parameters{
81+
.name = "T",
82+
.analogInputPin = A5,
83+
.referenceResistance = 100,
84+
.resistanceRange = {.min = 0, .max = 92},
85+
.outputRange = {.min = 0, .max = 127},
86+
}},
87+
};
88+
5589
void setup()
5690
{
5791
Serial.begin(9600);
5892

5993
hc165_collection_setup(hc165_collection);
6094
hc165_collection_read(hc165_collection);
6195
hc165_collection_print(hc165_collection);
62-
63-
analogReference(DEFAULT);
64-
pinMode(A0, INPUT);
65-
pinMode(A1, INPUT);
66-
pinMode(A4, INPUT);
67-
pinMode(A5, INPUT);
68-
}
69-
70-
/*
71-
* Attempting to read the voltage across only a potentiometer will always
72-
* return 1023. The voltage difference is 5V because there is nothing else in
73-
* the circuit. To measure the resistance, we use a reference resistor in
74-
* series with the potentiometer:
75-
*
76-
* 5V --v^v^v-- V1 --v^v^v-- GROUND
77-
* Rpot Rref
78-
*
79-
* To solve for Rpot, use Ohm's law and the fact that 2 resistors in series
80-
* must have the same current:
81-
*
82-
* (Vsupply - V1) / Rpot = (V1 - 0V) / Rref
83-
* (Vsupply - V1) * Rref = V1 * Rpot
84-
* (Vsupply / V1 - 1) * Rref = Rpot
85-
* Vsupply * Rref / V1 - Rref = Rpot
86-
*
87-
* The ADC maps 5V (assumed to be both the ADC reference voltage and the supply
88-
* voltage) to a value 0 - 1023 (kAdcOutputMax). Since only the ratio of
89-
* Vsupply and V1 is important, we can treat both as ADC outputs instead of
90-
* converting from ADC to voltage on both sides.
91-
*
92-
* See http://www.built-to-spec.com/blog/2009/09/10/using-a-pc-joystick-with-the-arduino/
93-
*/
94-
const long kDivResistanceKOhm = 100;
95-
const long kAdcOutputMax = 1023;
96-
97-
uint8_t get_potentiometer_resistance(int adc_in)
98-
{
99-
if(adc_in > 0) {
100-
return uint8_t((kAdcOutputMax * kDivResistanceKOhm) / adc_in - kDivResistanceKOhm);
101-
} else {
102-
return 0;
103-
}
10496
}
10597

10698
void loop()
@@ -119,17 +111,13 @@ void loop()
119111
}
120112

121113
if(!isButtonPressed) {
122-
Serial.print("Axes: x:");
123-
Serial.print(get_potentiometer_resistance(analogRead(A0)));
124-
Serial.print(" y:");
125-
Serial.print(get_potentiometer_resistance(analogRead(A1)));
126-
Serial.print(" r:");
127-
Serial.print(get_potentiometer_resistance(analogRead(A4)));
128-
Serial.print(" t:");
129-
Serial.print(get_potentiometer_resistance(analogRead(A5)));
130-
Serial.print("\r\n");
114+
Serial.print("axes:");
115+
for(const Potentiometer& axesPotentiometer : axesPotentiometers) {
116+
Serial.print(' ');
117+
Serial.print(axesPotentiometer);
118+
}
119+
Serial.println();
131120
}
132121

133122
delay(POLL_DELAY_MSEC);
134-
}
135-
123+
}

‎library.properties

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,4 +7,4 @@ paragraph=Replaces the main logic board in the Gravis Phoenix with an Arduino.
77
category=Other
88
url=https://github.com/BinaryMan32/phoenix-arduino
99
architectures=avr
10-
includes=hc165.h
10+
includes=hc165.h,Potentiometer.h,Fraction.h

‎src/Fraction.cpp

Lines changed: 118 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,118 @@
1+
#include <Print.h>
2+
3+
#include "Fraction.h"
4+
5+
long gcf(long a, long b)
6+
{
7+
return (b == 0) ? a : gcf(b, a % b);
8+
}
9+
10+
long simplifyFraction(long& numerator, long& denominator)
11+
{
12+
long factor = gcf(numerator, denominator);
13+
if(factor > 1) {
14+
numerator /= factor;
15+
denominator /= factor;
16+
}
17+
return factor;
18+
}
19+
20+
Fraction::Fraction(long numerator, long denominator)
21+
: mNumerator{numerator}, mDenominator{denominator}
22+
{
23+
simplifyFraction(mNumerator, mDenominator);
24+
if(mDenominator < 0) {
25+
mNumerator = -mNumerator;
26+
mDenominator = -mDenominator;
27+
}
28+
}
29+
30+
Fraction Fraction::getInverse() const
31+
{
32+
return Fraction{mDenominator, mNumerator, AlreadySimplifiedTag{}};
33+
}
34+
35+
long Fraction::getResultRounded() const
36+
{
37+
return (mNumerator + mDenominator / 2) / mDenominator;
38+
}
39+
40+
size_t Fraction::printTo(Print& p) const
41+
{
42+
return p.print('(') + p.print(mNumerator) + p.print('/')
43+
+ p.print(mDenominator) + p.print(")~=") + p.print(getResultRounded());
44+
}
45+
46+
Fraction Fraction::operator-() const
47+
{
48+
return Fraction{-mNumerator, mDenominator, AlreadySimplifiedTag{}};
49+
}
50+
51+
Fraction::Fraction(long numerator, long denominator, AlreadySimplifiedTag)
52+
: mNumerator{numerator}, mDenominator{denominator}
53+
{
54+
}
55+
56+
Fraction operator + (long factor, const Fraction& fraction)
57+
{
58+
return Fraction{factor * fraction.mDenominator + fraction.mNumerator,
59+
fraction.mDenominator};
60+
}
61+
62+
Fraction operator + (const Fraction& fraction, long factor)
63+
{
64+
return factor + fraction;
65+
}
66+
67+
Fraction operator + (const Fraction& a, const Fraction& b)
68+
{
69+
const long factor = gcf(a.mDenominator, b.mDenominator);
70+
return Fraction{a.mNumerator * (b.mDenominator / factor) +
71+
b.mNumerator * (a.mDenominator / factor),
72+
(a.mDenominator / factor) * b.mDenominator};
73+
}
74+
75+
Fraction operator - (long factor, const Fraction& fraction)
76+
{
77+
return (-factor) + fraction;
78+
}
79+
80+
Fraction operator - (const Fraction& fraction, long factor)
81+
{
82+
return (-factor) + fraction;
83+
}
84+
85+
Fraction operator - (const Fraction& a, const Fraction& b)
86+
{
87+
return a + (-b);
88+
}
89+
90+
Fraction operator * (long factor, const Fraction& fraction)
91+
{
92+
return Fraction(factor * fraction.mNumerator, fraction.mDenominator);
93+
}
94+
95+
Fraction operator * (const Fraction& fraction, long factor)
96+
{
97+
return factor * fraction;
98+
}
99+
100+
Fraction operator * (const Fraction& a, const Fraction& b)
101+
{
102+
Fraction(a.mNumerator * b.mNumerator, a.mDenominator * b.mDenominator);
103+
}
104+
105+
Fraction operator / (long factor, const Fraction& fraction)
106+
{
107+
return factor * fraction.getInverse();
108+
}
109+
110+
Fraction operator / (const Fraction& fraction, long factor)
111+
{
112+
return fraction * Fraction{1, factor, Fraction::AlreadySimplifiedTag{}};
113+
}
114+
115+
Fraction operator / (const Fraction& a, const Fraction& b)
116+
{
117+
return a * b.getInverse();
118+
}

‎src/Fraction.h

Lines changed: 91 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,91 @@
1+
#ifndef PHOENIX_ARDUINO_FRACTION_H
2+
#define PHOENIX_ARDUINO_FRACTION_H
3+
4+
#include <Printable.h>
5+
6+
/*
7+
* Euclid's algorithm to find GCF (Greatest Common Factor) of a and b.
8+
* Note that gcf(0, X) == gcf(X, 0) == X.
9+
*/
10+
long gcf(long a, long b);
11+
12+
/*
13+
* Simplify a fraction by dividing the numerator and denominator by the GCF
14+
* (Greatest Common Factor). Return the GCF.
15+
*/
16+
long simplifyFraction(long& numerator, long& denominator);
17+
18+
class Fraction : public Printable
19+
{
20+
public:
21+
/**
22+
* Create from numerator and denominator
23+
*/
24+
Fraction(long numerator, long denominator);
25+
26+
/**
27+
* Returns a new Fraction (denominator / numerator).
28+
*/
29+
Fraction getInverse() const;
30+
31+
/**
32+
* Get result of (numerator / denomonator as a rounded whole number
33+
*/
34+
long getResultRounded() const;
35+
36+
/**
37+
* Enables printing the Fraction via Serial.print(Fraction{1, 2})
38+
*/
39+
size_t printTo(Print& p) const override;
40+
41+
/** Unary negation */
42+
Fraction operator-() const;
43+
44+
protected:
45+
/**
46+
* Tag used internally to construct an already simplified fraction.
47+
*/
48+
struct AlreadySimplifiedTag {};
49+
50+
/**
51+
* Construct a Fraction which is already simplified.
52+
*/
53+
Fraction(long numerator, long denominator, AlreadySimplifiedTag);
54+
55+
long mNumerator;
56+
long mDenominator;
57+
58+
friend Fraction operator + (long factor, const Fraction& fraction);
59+
friend Fraction operator + (const Fraction& fraction, long factor);
60+
friend Fraction operator + (const Fraction& a, const Fraction& b);
61+
62+
friend Fraction operator - (long factor, const Fraction& fraction);
63+
friend Fraction operator - (const Fraction& fraction, long factor);
64+
friend Fraction operator - (const Fraction& a, const Fraction& b);
65+
66+
friend Fraction operator * (long factor, const Fraction& fraction);
67+
friend Fraction operator * (const Fraction& fraction, long factor);
68+
friend Fraction operator * (const Fraction& a, const Fraction& b);
69+
70+
friend Fraction operator / (long factor, const Fraction& fraction);
71+
friend Fraction operator / (const Fraction& fraction, long factor);
72+
friend Fraction operator / (const Fraction& a, const Fraction& b);
73+
};
74+
75+
Fraction operator + (long factor, const Fraction& fraction);
76+
Fraction operator + (const Fraction& fraction, long factor);
77+
Fraction operator + (const Fraction& a, const Fraction& b);
78+
79+
Fraction operator - (long factor, const Fraction& fraction);
80+
Fraction operator - (const Fraction& fraction, long factor);
81+
Fraction operator - (const Fraction& a, const Fraction& b);
82+
83+
Fraction operator * (long factor, const Fraction& fraction);
84+
Fraction operator * (const Fraction& fraction, long factor);
85+
Fraction operator * (const Fraction& a, const Fraction& b);
86+
87+
Fraction operator / (long factor, const Fraction& fraction);
88+
Fraction operator / (const Fraction& fraction, long factor);
89+
Fraction operator / (const Fraction& a, const Fraction& b);
90+
91+
#endif /* PHOENIX_ARDUINO_FRACTION_H */

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