i2c bus goes down when connexting CJMCU-350 Laser Time of flight module to UNO

Using Arduino Sensors
1

Hi folks,

I am fighting to implement the first i2c module on an arduino. After checking quite some time I found out the following.

When starting i2c I get clean signals on my SDA, SCL pins of the Arduino (checked with my scope). But exactly the moment I connect the SDA, SCL to the laser module my bus voltage drops to 2,5 V (both clock and data) and of course the port scan I am running halts.

The same problem occurs if the laser module is not powered and I only connect ehe SDA, SCL lines.

Are there any settings or issues that can couse this behaviour or is the device simply broken (I have only bought one so this is a possibility).

I am using wires that are approximately 50cm which is rather long ... but if this causes problems I would expect that I loose data or the signals get week and not that the bus goes down immidiately

regards
Bumo

2

Ho do you power up a sensor? Is it 3,3V? Please, provide a link to product specification.
Likely, you need a voltage converter module to interface with UNO, 3.3V<->5V

3

With respect to some entries I found on the web I can run with 5V as it has a linear voltage regulator on board (LG33).

Meanwhile I have changed the environment as I have added external pullup resistors of 5k1 to both clock and data.

The scope shows better signals now, without connection, then ...

  1. connecting SDA, SCL first, the volatage levels ot the data signal drop for some signals to 2,5V and stays on 5 V on others.
  2. as soon as I connet 5 V to the sensor the bus hangs

regards
Michael

4

Power line and data lines are different species. Even you can power module from 5V, SDA & SCK are likely still need to see 3.3V level voltage. Conecting to +5V (arduino UNO SDA SCK are 5V) is a way to kill a sensor.