SRF02 Ultrasonic range finder

Technical Specification

I2C Mode

I2C Communication

To use the SRF02 in I2C mode, make sure nothing is connected to the mode pin, it must be left

unconnected.

The I2C bus is available on popular controllers such as the OOPic, Stamp BS2p, PicAxe etc. as well as a

wide variety of micro-controllers. To the programmer the SRF02 behaves in the same way as the ubiquitous

24xx series EEPROM's, except that the I2C address is different. The default shipped address of the SRF02 is

F8, FA, FC or FE, therefore up to 16 sonar's can be used.

Connections

The connections to the SRF02 are identical to the SRF08 and SRF10 rangers. The "Mode" pin should be left

unconnected, it has an internal pull-up resistor. The SCL and SDA lines should each have a pull-up resistor

to +5v somewhere on the I2C bus. You only need one pair of resistors, not a pair for every module. They are

normally located with the bus master rather than the slaves. The SRF02 is always a slave - never a bus

master. If you need them, I recommend 1.8k resistors. Some modules such as the OOPic already have pull-

up resistors and you do not need to add any more.

Registers

The SRF02 appears as a set of 6 registers.

Only location 0 can be written to. Location 0 is the command register and is used to start a ranging session.

It cannot be read. Reading from location 0 returns the SRF02 software revision. The ranging lasts up to

65mS, and the SRF02 will not respond to commands on the I2C bus whilst it is ranging.

Location

Read

Write

0

Software

Revision

Command Register

1

Unused (reads

0x80)

N/A

2

Range High Byte

N/A

3

Range Low Byte

N/A

4

Autotune

Minimum - High

Byte

N/A

5

Autotune

Minimum - Low

Byte

N/A