i2c scanner does not detects my i2c device

Projects Networking, Protocols, and Devices
1

I am connecting a azoteq track pad module(https://www.azoteq.com/product/i2c-trackpad-modules/) to arduino uno via i2c . The arduino sample code that was provided with azoteq module works correctly and consistently, but when I use i2c scanner . it shows "no devices detected " . If i remove power to the module and connect it then it detects for the first time and after that again it shows " no devices detected" .

Could you please help me understand this behaviour , my objective is to be able to consistently see the device address using the i2c scanner .

Many thanks for the help .

2

My guess is an error in the circuit but you failed to provide a wiring diagram as well as the used code.

Problematic is that the UNO works on 5V while the track pad allows only 3.3V. Nevertheless, if the example code works a correct I2C scanner should detect the device.

3

I see that the scanner from the playground simply sends an empty message to each address on the bus and if it gets a response, knows that there is an I2C device there.

Perhaps this device doesn't respond to a null message or, since it apparently does respond once, perhaps such a message either crashes it or configures it in some way.

Perhaps you could try using a legitimate message instead - ask the device for it's version number for example. There's code to do that in the example app apparently.

4

I see that the scanner from the playground simply sends an empty message to each address on the bus and if it gets a response, knows that there is an I2C device there.

This is not completely correct. It sends the address to the I2C bus and an active I2C device must respond with an ACK response. Devices that don't respond that way are not I2C compatible.

Perhaps you could try using a legitimate message instead - ask the device for it's version number for example. There's code to do that in the example app apparently.

That probably won't succeed. The only way I can see is if the device doesn't support any write instruction but only allows reading but a track pad isn't that simple that only readings may be sufficient to use the device.