8 years, 2 months ago.

SRF08 not working??

Hi

frist the program code

#include "mbed.h"

Serial pc(USBTX,USBRX);     // Tx, Rx Pin, default boud = 9600
I2C i2c(p9, p10);          // SDA, SCL

int main()
{
    char cmd[2];            // Command
    char echo[2];           // Echo result data (8bit)
    char echo2[2];
    int  addr  = 0xE0;      // Defalut I2C address of SRF08
    float  range = 0;         // Rage data (16bit, cm)
    float  range2 = 0;         // Rage data (16bit, cm)

    i2c.frequency(40000);
    while(1) {
        cmd[0] = 0x00;          // Register(Command)
        cmd[1] = 0x51;          // Ranging mode - Result in centimeters
        if(!i2c.write(addr,cmd,2)) {
            pc.printf("Raging ACK ");
            wait(0.17);
            cmd[0] = 0x02;          // Register(1st Echo)
            if(!i2c.write(addr,cmd,1,1)) {
                // Send I2C data (8bit*1)
                pc.printf("1st echo write ACK ");
                if(!i2c.read(addr,echo,2)) {
                    pc.printf("1st echo read ACK ");
                    int cm = ((echo[0]<<8)+echo[1]);
                    range = ((echo[0]<<8)+echo[1]);
                    pc.printf("Range : %d cm \n",cm);
                } else {
                    pc.printf("1st echo read NOT ACK\n");
                }

            } else {
                pc.printf("1st echo write NOT ACK\n");
            }
        } else {
            pc.printf("Raging NOT ACK\n");
        }
        wait(0.5);
    }
}

My problem is that the sonar sensor only gives me three values 5,6 and 7? what is the meaning of this? what am i doing wrong?

the sensor is set to the default values, 6m, max gain.

Thank you

2 Answers

8 years, 2 months ago.

You are running I2C at 40 kHz.? Is that what you want? Guenter.

8 years, 2 months ago.

Yes i am running at 40 kHz, my problem is that SRF08 does not work for inches and miliSeconds, only fo Centimeters, but even in cm it returns constant values.

Can anyone help?

Maybe the sensor is broken?