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--- en:examples:sensor:lidar [2012/05/30 08:41] – raivo.sell
+++ en:examples:sensor:lidar [2020/07/20 09:00] (current) – external edit 127.0.0.1
@@ Line 4: / Line 4: @@
 //Necessary knowledge: [HW] [[en:hardware:homelab:communication]], [HW] [[en:hardware:homelab:digi]],  [LIB] [[en:software:homelab:library:usart]], [LIB] [[en:software:homelab:library:module:lcd_graphic]], [LIB] [[en:software:homelab:library:module:sensor]]//
+===== Theory =====
-[{{   :en:examples:sensor:lidar3.jpg?220|SICK Laser Rangefinder (LIDAR)}}]
+[{{  :en:examples:sensor:lidar3.jpg?220|SICK Laser Rangefinder (LIDAR)}}]
-===== Theory =====
 LIDAR (Light Detection and Ranging) is an optical remote sensing system which can measure the distance of a target by illuminating it with light. LIDAR technology is being used in Robotics for the perception of the environment as well as object classification. The ability of LIDAR technology to provide 2D elevation maps of the terrain, high precision distance to the ground, and approach velocity can enable safe landing of robotic and manned vehicles with a high degree of precision.
@@ Line 28: / Line 26: @@
 c = f ∙ τ
-where c is the speed of light and f the modulating frequency, and τ the known modulating wavelength.
+where c is the speed of light and f the modulating frequency and τ the known modulating wavelength.
 The total distance D' covered by the emitted light is:
@@ Line 69: / Line 67: @@
 Decimal Form:	        2	0	2	0	32	37	53	8
-Following example shows how to initiate Lidar and measure the distance.
+Following example shows how to initiate Lidar and get the count of package.
 <code c>
+#include <stdio.h>
+#include <homelab/delay.h>
+#include <homelab/pin.h>
+#include <homelab/module/lcd_gfx.h>
+#include <homelab/usart.h>
-</code>
+// Defining USART interface.
+usart port = USART(0);
+// Defining button pins.
+pin button1 = PIN(C, 0);
+pin button2 = PIN(C, 1);
+// Initialize
+static inline void init()
+{
+	// Setting buttons pins as inputs.
+	pin_setup_input_with_pullup(button1);
+	pin_setup_input_with_pullup(button2);
+	// Set-up of the LCD.
+	lcd_gfx_init();
+ 	// Cleaning the screen.
+	lcd_gfx_clear();
+ 	// Switching on the background light.
+	lcd_gfx_backlight(true);
+ 	// Displaying the name of the program.
+	lcd_gfx_goto_char_xy(3, 1);
+	lcd_gfx_write_string("Lidar");
+	// The set-up of the USART interface.
+	usart_init_async
+	(
+		port,
+		USART_DATABITS_8,
+		USART_STOPBITS_ONE,
+		USART_PARITY_NONE,
+		USART_BAUDRATE_ASYNC(9600)
+	);
+}
+// Main program
+int main(void)
+{
+	unsigned char new_value1, new_value2, old_value1 = 0, old_value2 = 0;
+	char c;
+	int i = 0;
+	int count = 0;
+	char text[16];
+	// Initialize
+	init();
+	// Endless cycle
+	while (1)
+	{
+		// Reads buttons states
+		new_value1 = pin_get_debounced_value(button1);
+		new_value2 = pin_get_debounced_value(button2);
+		// Button S1 is pressed.
+		if((!new_value1) && (old_value1))
+		{
+			//Send "02 00 02 00 20 24 34 08" to start scanning.
+			usart_send_char(port, 0x02);
+			usart_send_char(port, 0x00);
+			usart_send_char(port, 0x02);
+			usart_send_char(port, 0x00);
+			usart_send_char(port, 0x20);
+			usart_send_char(port, 0x24);
+			usart_send_char(port, 0x34);
+			usart_send_char(port, 0x08);
+		}
+		// Button S2 is pressed.
+		if((!new_value2) && (old_value2))
+		{
+			//Send "0x 02 00 02 00	20 25 35 08" to stop scanning.
+			usart_send_char(port, 0x02);
+			usart_send_char(port, 0x00);
+			usart_send_char(port, 0x02);
+			usart_send_char(port, 0x00);
+			usart_send_char(port, 0x20);
+			usart_send_char(port, 0x25);
+			usart_send_char(port, 0x35);
+			usart_send_char(port, 0x08);
+		}
+		// Remembers the last keys values.
+		old_value1 = new_value1;
+		old_value2 = new_value2;
+		// Try to read serial port
+		if (usart_try_read_char(port, &c))
+		{
+			// Find a header "0x 02 81 D6 02 B0 69 41"
+			// Very basic package start search.
+			if(c == 0x02) i++;
+			if(c == 0x81) i++;
+			if(c == 0xD6) i++;
+			if(c == 0x02) i++;
+			if(c == 0xB0) i++;
+			if(c == 0x69) i++;
+			if(c == 0x41) i++;
+			//If there is an header
+			if(i >= 7)
+			{
+				//Increse packet counter
+				count++;
+				//Displaying packet count on the LCD.
+				lcd_gfx_goto_char_xy(0, 3);
+				sprintf(text, "Pakette: %i", count);
+				lcd_gfx_write_string(text);
+				i=0;
+			}
+		}
+	}
+}
+</code>

en/examples/sensor/lidar.1338367266.txt.gz · Last modified: 2020/07/20 09:00 (external edit)