Syed Aftab

Important changes to forums and questions

All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.

10 years, 7 months ago.

Can Mbed I2C Master drive a slave working at 3.5 volts?

Hi

I have a problem i am trying to connect my mbed with a PLC kit i brought from cypress it works at 3.5 as input for I2C. Can the Mbed drive a slave with these specifications ??

as it outputs 3.3 volts ...

can anyone help ??

1 Answer

Wim Huiskamp
10 years, 7 months ago.

The 3v3 outputs should work. Use pullups resistors to mbeds 3v3 vout. You can also use levelconverters like those offered by sparkfun and others, but in this case the leveldifference is small and should not be a problem, in particular when no other slave or masterdevices are using the same bus.

Accepted Answer

Thanks Wim

I am trying to use mbed with PLC kit by cypress i.e. http://www.cypress.com/?rID=38024

I have been trying to communicate with the kit using I2C but Master (mbed) does not write anything to the device. It just gets stuck during the write operation and never returns ?? what could the problem be ??

posted by Syed Aftab 19 Sep 2013

Mbed will get stuck when pullup Rs are missing or when sda and scl are reversed. Also make sure you have a common ground.

posted by Wim Huiskamp 19 Sep 2013