Initial upload

examples/PPM-decoder/PPM.cpp

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+/*
+This code is provided under the BSD license.
+Copyright (c) 2014, Emlid Limited. All rights reserved.
+Written by Mikhail Avkhimenia (mikhail.avkhimenia@emlid.com)
+twitter.com/emlidtech || www.emlid.com || info@emlid.com
+
+Application: PPM to PWM decoder for Raspberry Pi with Navio.
+
+Requres pigpio library, please install it first - http://abyz.co.uk/rpi/pigpio/
+To run this app navigate to the directory containing it and run following commands:
+make
+sudo ./PPM
+*/
+
+#include <pigpio.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <darkwater/gpio.h>
+#include "darkwater/PCA9685.h"
+#include "darkwater/Util.h"
+
+//================================ Options =====================================
+
+unsigned int samplingRate      = 1;      // 1 microsecond (can be 1,2,4,5,10)
+unsigned int ppmInputGpio      = 4;      // PPM input on Navio's 2.54 header
+unsigned int ppmSyncLength     = 4000;   // Length of PPM sync pause
+unsigned int ppmChannelsNumber = 8;      // Number of channels packed in PPM
+unsigned int servoFrequency    = 50;     // Servo control frequency
+bool verboseOutputEnabled      = true;   // Output channels values to console
+
+//============================ Objects & data ==================================
+
+PCA9685 *pwm;
+float channels[8];
+
+//============================== PPM decoder ===================================
+
+unsigned int currentChannel = 0;
+unsigned int previousTick;
+unsigned int deltaTime;
+
+void ppmOnEdge(int gpio, int level, uint32_t tick)
+{
+	if (level == 0) {	
+		deltaTime = tick - previousTick;
+		previousTick = tick;
+	
+		if (deltaTime >= ppmSyncLength) { // Sync
+			currentChannel = 0;
+
+			// RC output
+			for (int i = 0; i < ppmChannelsNumber; i++)
+			    pwm->setPWMuS(i + 3, channels[i]); // 1st Navio RC output is 3
+
+			// Console output
+			if (verboseOutputEnabled) {
+				printf("\n");
+				for (int i = 0; i < ppmChannelsNumber; i++)
+					printf("%4.f ", channels[i]);
+			}
+		}
+		else
+			if (currentChannel < ppmChannelsNumber)
+				channels[currentChannel++] = deltaTime;
+	}
+}
+
+//================================== Main ======================================
+
+using namespace Navio;
+
+int main(int argc, char *argv[])
+{
+    static const uint8_t outputEnablePin = RPI_GPIO_27;
+
+    if (check_apm()) {
+        return 1;
+    }
+    
+    Pin pin(outputEnablePin);
+
+    if (pin.init()) {
+        pin.setMode(Pin::GpioModeOutput);
+        pin.write(0); /* drive Output Enable low */
+    } else {
+        fprintf(stderr, "Output Enable not set. Are you root?");
+    }
+
+	// Servo controller setup
+
+	pwm = new PCA9685();
+	pwm->initialize();
+	pwm->setFrequency(servoFrequency);
+
+	// GPIO setup
+
+	gpioCfgClock(samplingRate, PI_DEFAULT_CLK_PERIPHERAL, 0); /* last parameter is deprecated now */
+	gpioInitialise();
+	previousTick = gpioTick();
+	gpioSetAlertFunc(ppmInputGpio, ppmOnEdge);
+
+	// Infinite sleep - all action is now happening in ppmOnEdge() function
+
+	while(1)
+		sleep(10);
+	return 0;
+}