Added small programming to compute ws2811 timing

Former-commit-id: 3f62bca1476b1cba17946c309482e595f68c1698

test/CMakeLists.txt

@@ -49,6 +49,8 @@ add_executable(spidev_test spidev_test.c)
 
 add_executable(gpio2spi switchPinCtrl.c)
 
+add_executable(determineWs2811Timing DetermineWs2811Timing.cpp)
+
 add_executable(test_rs232highspeed
 		TestRs232HighSpeed.cpp
 		../libsrc/leddevice/LedRs232Device.cpp

test/DetermineWs2811Timing.cpp

@@ -0,0 +1,60 @@
+
+// STl includes
+#include <iostream>
+#include <cmath>
+
+bool requiredTiming(const int tHigh_ns, const int tLow_ns, const int error_ns, const int nrBits)
+{
+	std::cout << "=== " << nrBits << " bits case ===== " << std::endl;
+	double bitLength_ns = (tHigh_ns + tLow_ns)/double(nrBits);
+	double baudrate_Hz  = 1.0 / bitLength_ns * 1e9;
+	std::cout << "Required bit length: " << bitLength_ns << "ns => baudrate = " << baudrate_Hz << std::endl;
+
+	double highBitsExact = tHigh_ns/bitLength_ns;
+	int highBits = std::round(highBitsExact);
+	double lowBitsExact  = tLow_ns/bitLength_ns;
+	int lowBits  = std::round(lowBitsExact);
+	std::cout << "Bit division: high=" << highBits << "(" << highBitsExact << "); low=" << lowBits << "(" << lowBitsExact << ")" << std::endl;
+
+	double highBitsError = std::fabs(highBitsExact - highBits);
+	double lowBitsError  = std::fabs(highBitsExact - highBits);
+	double highError_ns = highBitsError * bitLength_ns;
+	double lowError_ns  = lowBitsError * bitLength_ns;
+
+	if (highError_ns > error_ns || lowError_ns > error_ns)
+	{
+		std::cerr << "Timing error outside specs: " << highError_ns << "; " << lowError_ns << " > " << error_ns << std::endl;
+	}
+	else
+	{
+		std::cout << "Timing within margins: " << highError_ns << "; " << lowError_ns << " < " << error_ns << std::endl;
+	}
+
+
+
+	return true;
+}
+
+int main()
+{
+	// 10bits
+	requiredTiming(400, 850, 150, 10);	// Zero
+	requiredTiming(800, 450, 150, 10);	// One
+
+	// 6bits
+	requiredTiming(400, 850, 150, 6);	// Zero
+	requiredTiming(800, 450, 150, 6);	// One
+
+	// 5bits
+	requiredTiming(400, 850, 150, 5);	// Zero
+	requiredTiming(800, 450, 150, 5);	// One
+
+	// 4bits
+	requiredTiming(400, 850, 150, 4);	// Zero
+	requiredTiming(800, 450, 150, 4);	// One
+
+	// 3bits
+	requiredTiming(400, 850, 150, 3);	// Zero
+	requiredTiming(800, 450, 150, 3);	// One
+	return 0;
+}