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[on:]

Hi,
really newbie in big troubles!
I'm trying to get readings from a Devantech SRF08 ultrasound sensor
connected to an Arduino using I2C/TWI
(actually I'm using digital input 0 and 1 on Arduino for the SCL and SDA: is it correct?).

I've found some code made by
Nicholas Zambetti <http://www.zambetti.com> and James Tichenor <http://www.jamestichenor.net>
but when I try to upload it to the board I always get a message saying
"Sketch too big; try deleting code, removing floats, or see (...)
Binary sketch size: 7970bytes (of a 7168 byte maximum)"
I can't delete pieces of code, maybe some lines in the "TwoWire.h" included but really don't know...

What can I do to make it work?
Can Arduino be used with this sonar or
do I have to get something else? (another sonar or another board)

Please help, I'm stuck on this!
gio

- SRF08 code-------------------

#include <TwoWire.h>

void setup()
{
  Wire.begin();                // join i2c bus (address optional for master)
  Serial.begin(19200);          // start serial communication at 19200bps
}

int reading = 0;

void loop()
{
  // step 1: instruct sensor to read echoes
  Wire.beginTransmission(112); // transmit to device #112 (0x70)
  // the address specified in the datasheet is 224 (0xE0)
  // but i2c adressing uses the high 7 bits so it's 112
  Wire.send(0x00);             // sets register pointer to the command register (0x00)  
  Wire.send(0x51);             // command sensor to measure in cm (0x51)
  // use 0x52 for ping microseconds
  Wire.endTransmission();      // stop transmitting

  // step 2: wait for readings to happen
  delay(70);                   // datasheet suggests at least 65 milliseconds

  // step 3: instruct sensor to return a particular echo reading
  Wire.beginTransmission(112); // transmit to device #112
  Wire.send(0x02);             // sets register pointer to echo #1 register (0x02)
  Wire.endTransmission();      // stop transmitting

  // step 4: request reading from sensor
  Wire.requestFrom(112, 2);    // request 2 bytes from slave device #112

    // step 5: receive reading from sensor
  if(2 <= Wire.available())    // if two bytes were received
  {
    reading = Wire.receive();  // receive high byte (overwrites previous reading)
    reading = reading << 8;    // shift high byte to be high 8 bits
    reading |= Wire.receive(); // receive low byte as lower 8 bits
    Serial.println(reading);   // print the reading
  }

  delay(250);                  // wait 250ms
}

[Reply #1 on:]

i'll reply to myself,
you can't use srf08 with arduino,
get maxbotix ez-1 instead,
it's cheaper, got the same range and is much simpler to use (interfacing+coding)

[Reply #2 on:]

I am too researching on ultrasonic distance measuring and came across the MaxSonar-EZ1. As of today I wasn't able to find dealers (in germany) selling the PING made by Parallax, which seem to be sold as units of 4 devices  :-? but I still need to find a supplier of the EZ1 here in germany.

What did you finally do to resolve the problem concerning the size of the sketch?

Did you see this article http://itp.nyu.edu/physcomp/sensors/Reports/SRF04SonarRangerfor interfacing with the SRF?

[Reply #3 on:]

Hi,
maybe the new arduino software release (0005 - 2006.09.06 )
can solve the problem, if the extra 1k memory
"Smaller core libraries (~4.5 KB instead of 5.5 KB)"
is enough to store the i2c code...
don't have much time to do this now, I'll let you know if I manage to make it work.
Anyway you can but the ez1 sonar from www.sparkfun.com,
if you need something already working and tested, get the ez1.
Have nice days,
ciao
gio

[Reply #4 on:]

You may as well buy them directly from maxbotix.com, payments via PayPal or credit cards accepted. Why bother a supplier  
Once I'll have enough dough for three units, I'll have a got at them too!