To change the I2C address of the SRF02 you must have only one sonar on the bus. Write the 3 sequence

commands in the correct order followed by the address. Example; to change the address of a sonar currently

at 0xE0 (the default shipped address) to 0xF2, write the following to address 0xE0; (0xA0, 0xAA, 0xA5,

0xF2 ). These commands must be sent in the correct sequence to change the I2C address, additionally, No

other command may be issued in the middle of the sequence. The sequence must be sent to the command

register at location 0, which means 4 separate write transactions on the I2C bus. When done, you should

label the sonar with its address, however if you do forget, just power it up without sending any commands.

The SRF02 will flash its address out on the LED. One long flash followed by a number of shorter flashes

indicating its address. The flashing is terminated immediately on sending a command the SRF02.

Take care not to set more than one sonar to the same address, there will be a bus collision and very

unpredictable results.

Note - there is only one module address stored in the SRF02. If you change it, the equivalent Serial Mode

address will also change:

0xE0, 0xE2, 0xE4, 0xE6, 0xE8, 0xEA, 0xEC, 0xEE, 0xF0, 0xF2, 0xF4, 0xF6,

0xF8, 0xFA, 0xFC, 0xFE I2C addresses

0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B,

0x0C, 0x0D, 0x0E, 0x0F Equivalent Serial addresses

AutoTune

The SRF02 does not require any user calibration. You power up and go right ahead and use the SRF02.

Internally, there are tuning cycles happening automatically in the background. After the ultrasonic burst has

been transmitted, the transducer keeps on ringing for a period of time. It is this ringing which limits the

closest range the SRF02 can measure. This time period varies with temperature and from transducer to

transducer, but is normally the equivalent of 11 to 16cm (4" to 6"), a bit more if the transducer is warm. The

SRF02 is able to detect the transducer ring time and move its detection threshold right up to it, giving the

SRF02 the very best performance possible. On power up, the detection threshold is set to 28cm (11"). The

tuning algorithms quickly back this right up to the transducer ring. This happens within 5-6 ranging cycles -

less than half a second at full scan speed. After this the tuning algorithms continue to monitor the transducer,

backing the threshold up even further when possible or easing it out a bit when necessary. The tuning

algorithms work automatically, in the background and with no impact on scan time.

The minimum range can be checked, if required by reading registers 4 and 5. This value is returned in uS,

cm or inches, the same as the range. It is also possible to make the SRF02 re-tune by writing command 96

but you can ignore this command. It is used during our testing.

Address

Long Flash Short flashes

Decimal

Hex

224

E0

1

0

226

E2

1

1

228

E4

1

2

230

E6

1

3

232

E8

1

4

234

EA

1

5

236

EC

1

6

238

EE

1

7

240

F0

1

8

242

F2

1

9

244

F4

1

10

246

F6

1

11

248

F8

1

12

250

FA

1

13

252

FC

1

14

254

FE

1

15