Hi,

I need to connect a PS/2 keyboard, which is a 5v device, to an FRDM-KL25Z MCU which is a 3.3v device, and would like to use the Freetronics LEVEL.

The clock and data lines need pullups. Does it matter on which side of the level converter they go?

Thanks,
Jim

 

If I remember correct correct .The PS2 keyboard is I2C based. The I2C use a float high, drive low approach. So the correct thing would in this case. Will be to have pullup resistor on the same side as the signal origin.

 

Looking at the circuit for the Freetronics product, it already has 10K pullups on both sides of the transistor that does the actual conversion, so it seems as if all you have to do is connect it up and you're ready to go. It's a clever use of components.

 

I was hoping it would be that simple. Thanks.