Add deadzone option to pedal serial calibration

This allows the user to set independent 'start' and 'end' deadzones for their pedal serial calibration. The purpose is to prevent pedals from being slightly pressed in their resting position, and to prevent pedals from reaching their 100% "pressed" position at full extension.

By default, this uses a 1% deadzone for the start of travel and a 2.5% deadzone for the end of travel.

I'm trying to be conservative here, because the last thing I want is for a user to set a large deadzone and then be unable to compensate for it when using the pedals as an HID device. Still, I think a tiny bit of fuzzing is good and can compensate for noise at the input extremes.

Author: dmadison

src/SimRacing.cpp

@@ -447,8 +447,61 @@ void Pedals::serialCalibration(Stream& iface) {
 		pedalData[i].read();  // read position
 		pedalCal[i].max = pedalData[i].getPositionRaw();  // set max to the recorded position
 	}
+
+	// deadzone options
+	iface.println(separator);
+	iface.println();
+
+	float DeadzoneMin = 0.01;  // by default, 1% (trying to keep things responsive)
+	float DeadzoneMax = 0.025;  // by default, 2.5%
+
+	iface.println(F("These settings are optional. Send 'y' to customize. Send any other character to continue with the default values."));
+
+	iface.print(F("  * Pedal Travel Deadzone, Start: \t"));
+	iface.print(DeadzoneMin);
+	iface.println(F("  (Used to avoid the pedal always being slightly pressed)"));
+
+	iface.print(F("  * Pedal Travel Deadzone, End:   \t"));
+	iface.print(DeadzoneMax);
+	iface.println(F("  (Used to guarantee that the pedal can be fully pressed)"));
+
 	iface.println();
 
+	waitClient(iface);
+
+	if (iface.read() == 'y') {
+		iface.println(F("Set the pedal travel starting deadzone as a floating point percentage."));
+		readFloat(DeadzoneMin, iface);
+		iface.println();
+
+		iface.println(F("Set the pedal travel ending deadzone as a floating point percentage."));
+		readFloat(DeadzoneMax, iface);
+		iface.println();
+	}
+
+	flushClient(iface);
+
+	// calculate deadzone offsets
+	for (int i = 0; (i < getNumPedals()) && (i < MaxPedals); i++) {
+		auto &cMin = pedalCal[i].min;
+		auto &cMax = pedalCal[i].max;
+
+		const int range = abs(cMax - cMin);
+		const int dzMin = DeadzoneMin * (float)range;
+		const int dzMax = DeadzoneMax * (float)range;
+
+		// non-inverted
+		if (cMax >= cMin) {
+			cMax -= dzMax;  // 'cut' into the range so it limits sooner
+			cMin += dzMin;
+		}
+		// inverted
+		else {
+			cMax += dzMax;
+			cMin -= dzMin;
+		}
+	}
+
 	// print finished calibration
 	iface.println(F("Here is your calibration:"));
 	iface.println(separator);