connecting SRF08 ultrasonic sensor to 5700 with I2C

Rabbit
1

Hi everyone!

I recently purchased a rabbit board (5700 kit), and i need to connect it to SRF08 ultrasonic distance measurement sensor. The sensor uses I2C to communicate. I have a problem with connecting the sensor to the board. The sensor requires 5V, and my board only outputs 3.3V.

I’ve created a little schematic, explaining how i meant to connect the sensor to the board. Is connecting in this way allowed. I’m thinking about connecting grounds together, like on schematic, but I’m afraid that using two different power supplies and connecting them together can damage my board.

Data and clock lines would be connected to rabbit’s 3.3V output. Pull up resistors I’m thinking about using are 1.8kOhm.

Is connecting in this way safe, and if not, in what way would you recommend me to connect the sensor and the board.

Thank you!

2

Connecting the way you have shown will almost certainly lead to problems - up to and including damage to the Rabbbit 5000 processor on the board as you are connecting directly to it. There are lots of articles out ther showing how to do this safely - do a search for “interfacing 3.3v to 5v”. A quick look at the results shows a variety of ways to do this without causing damage.

Regards,
Peter