William Marshall / Mbed 2 deprecated EDP_mbed_Demo1

Demonstration program for mbed when plugged into the RS EDP (Embedded Development Platform) environment. Requires an EDP-AM-MC1 motor module with DC motor and an SRF08 Ultrasonic Rangefinder.

Dependencies:   mbed

main.cpp@0:f154cd1e30ff, 2010-12-16 (annotated)

Committer:
billmarshall
Date:
Thu Dec 16 10:52:45 2010 +0000
Revision:
0:f154cd1e30ff

        

        
Who changed what in which revision?

        

            
                
UserRevisionLine numberNew contents of line

            
            


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// EDP & mbed demonstration program using I2C and PWM: W.G.Marshall 2010





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// Requires EDP-AM-MC1 DC motor module





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// Uses SRF08 Ultrasonic Range Finder on I2C address 0xE0





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// Option link J217 on EDP mbed carrier changed from 1-2 to 2-3





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// Jumpers on EDP MC1 module will require setting to suit GPIO signals





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#include "mbed.h"





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I2C sonar(p9, p10);                         // Define SDA, SCL pins





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Serial pc(USBTX, USBRX);                    // Define Tx, Rx pins





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PwmOut motor(p23);                          // Define PWM output (EDP: EVG0_GPIO40)





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DigitalOut Brake(p19);                      // Define brake      (EDP: GPIO0)





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DigitalOut Direction(p24);                  // Define direction  (EDP: EVG1_GPIO42)





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DigitalOut L1(LED1);                        // User LEDs form bargraph





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DigitalOut L2(LED2);





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DigitalOut L3(LED3);





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DigitalOut L4(LED4);





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const int addr = 0xE0;                      // I2C device address for SRF08





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char cmd[2];





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char echo[3];





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// echo[0] = light level





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// echo[1] = MSB echo





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// echo[2] = LSB echo





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float temp8;





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float range;   





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float MotorPWM;





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int main() {





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// Set up SRF08 max range and receiver sensitivity





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    cmd[0] = 0x02;                          // Range register





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    cmd[1] = 0x1C;                          // Set max range about 100cm





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    sonar.write(addr, cmd, 2);





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    cmd[0] = 0x01;                          // Receiver gain register





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    cmd[1] = 0x1B;                          // Set max receiver gain





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    sonar.write(addr, cmd, 2);





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// Set up PWM and motor control





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    motor.period(0.00005);                  // Set PWM frequency = 20kHz





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    motor.write(1);                         // Motor speed = 0





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    Brake = 0;                              // Brake on = 1, Brake off = 0





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    Direction = 0;





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    printf("\n\n\rCollision Avoidance Program Vsn 1.2\n\r");





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    printf("\n\r Range   Light\n\r");





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    while (1) {





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// Get range data and light level from SRF08





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// Send Tx burst command over I2C bus





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        cmd[0] = 0x00;                      // Command register





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        cmd[1] = 0x51;                      // Ranging results in cm





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        sonar.write(addr, cmd, 2);          // Send ranging burst





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        wait(0.07);





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// Read back light level and range over I2C bus





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        cmd[0] = 0x01;                      // Address of light level





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        sonar.write(addr, cmd, 1, 1);       // Send address of light level       





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        sonar.read(addr, echo, 3);          // read light and echo result





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// Generate PWM mark/space ratio from range data





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        range = (echo[1]<<8)+echo[2];





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        MotorPWM = range/100;               // Turn range into PWM ratio





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        if (temp8 != 0) {





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           motor.write(1-MotorPWM);         // Update PWM ratio (0 -> 1.0)





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        }





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        else {





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           motor.write(1);                  // PWM ratio = 0





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        }





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        pc.printf("  %3.0f", range);





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        pc.printf("     %3d\r", echo[0]);





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// Keyboard input to toggle start/stop motor





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        if (pc.readable()) {                // Check for keyboard input





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           pc.getc();                       // Key pressed, clear buffer 





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           if (temp8 == 0) {                // Motor already stopped?





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              Brake = 0;                    // Brake off, start motor





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              temp8 = range;





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           }





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           else {                           // Motor running





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              Brake = 1;                    // Brake on, stop motor





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              temp8 = 0;





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           }





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        }





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        wait(0.1);                          // Wait for 100ms





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// Bargraph with mbed user LEDs





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        if (range > 70) {





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           L1 = 1, L2 = 1, L3 = 1, L4 = 1;





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        }





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        else if (range > 40) {





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           L1 = 1, L2 = 1, L3 = 1, L4 = 0;





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        }





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        else if (range > 25) {





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           L1 = 1, L2 = 1, L3 = 0, L4 = 0;





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        }





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        else if (range > 7) {





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           L1 = 1, L2 = 0, L3 = 0, L4 = 0;





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        }





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        else {





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           L1 = 0, L2 = 0, L3 = 0, L4 = 0;





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        }





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    }





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}