Differences

This shows you the differences between two versions of the page.

--- en:examples:sensor:ultrasonic_distance:srf05 [2010/12/22 10:43] – raivo.sell
+++ en:examples:sensor:ultrasonic_distance:srf05 [2020/07/20 12:00] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+====== Ultrasonic distance sensor SRF05 ======
+[{{  :examples:sensor:ultrasonic_distance:srf05.jpg?160|Ultrasonic distance sensor SRF05}}]
+The SRF05 is an evolutionary step from the SRF04, and has been designed to increase flexibility, increase range, and to reduce costs still further. As such, the SRF05 is fully compatible with the SRF04. Range is increased from 3 meters to 4 meters. A new operating mode (tying the mode pin to ground) allows the SRF05 to use a single pin for both trigger and echo.
+When the mode pin is left unconnected, the SRF05 operates with separate trigger and echo pins, like the SRF04. The SRF05 includes a small delay before the echo pulse.
+{{  :examples:sensor:ultrasonic_distance:srf05p1.jpg?580  }}
+{{  :examples:sensor:ultrasonic_distance:srf05tmb.gif?580  }}
+Following example uses one pin mode of SRF05.
+Code is based on the slightly modified HomeLab library 1.03 ultrasonic_measure function.
+Example is intended for the ATmega128 controller module and Sensor module (v5).
+<code c>
+#include <homelab/delay.h>
+#include <homelab/module/lcd_gfx.h>
+#include <homelab/timer.h>
+#include "homelab/common.h"
+#include "homelab/pin.h"
+#define ULTRASONIC_SPEED_OF_SOUND    33000 // cm/s
+//SRF05 1 pin mode
+pin srf05 = PIN(F,3);
+//external sensor selection (make sure that the resistor is monted on the RC socket)
+pin ext_sensors = PIN(G, 0);
+//////////////////////////// UH measure //////////////
+unsigned short ultrasonic_measure(pin srf05)
+{
+    // Pin setup
+    pin_setup_output(srf05);
+    // Set timer 3 to normal mode
+    // with period of F_CPU / 8
+    timer3_init_normal(TIMER3_PRESCALE_8);
+    // Create trigger pulse
+    pin_set(srf05);
+    // Reset timer
+    timer3_overflow_flag_clear();
+    timer3_set_value(0);
+    // Wait ~10 us
+    while (timer3_get_value() < 18) {}
+    // End trigger pulse
+    pin_clear(srf05);
+    //short delay
+    sw_delay_ms(1);
+    //set the pin as input
+    pin_setup_input_with_pullup(srf05);
+    // Wait for echo start
+    while (!pin_get_value(srf05))
+    {
+        // Timeout ?
+        if (timer3_overflow_flag_is_set())
+        {
+            return 0;
+        }
+    }
+    // Reset timer again
+    timer3_set_value(0);
+    // Wait for echo end
+    while (pin_get_value(srf05))
+    {
+        // Timeout ?
+        if (timer3_overflow_flag_is_set())
+        {
+            return 0;
+        }
+    }
+    // Convert time to distance:
+    //   distance = timer * (1 / (F_CPU / 8)) * speed / 2
+    return (unsigned long)timer3_get_value() *
+        ULTRASONIC_SPEED_OF_SOUND / (F_CPU / 4);
+}
+/////////////////////////   Main program  /////////////////////////////
+int main(void)
+{
+    int dist;
+    char text[16];
+    //set external sensor
+    pin_setup_output(ext_sensors);
+    pin_set(ext_sensors);
+    // LCD init
+    lcd_gfx_init();
+    lcd_gfx_clear();
+    while (true)
+    {
+        //Measure
+        dist = ultrasonic_measure(srf05);
+        //print to LCD
+        sprintf(text,"Distance: %d cm",dist);
+        lcd_gfx_goto_char_xy(0, 0);
+        lcd_gfx_write_string(text);
+        //0,5 s delay
+        sw_delay_ms(50);
+        //Clear LCD
+        lcd_gfx_clear();
+    }
+}
+</code>