Voltage Upscale and Downscale 2

[techaddiction]

Hi all,

First post! This place seems pretty friendly and full of helpful resources; I hope I can contribute the same amount that I gain from this site =)

Any how here is my question:

I have a system with three main components:

1. microcontroller with VDD @ 5V
2. a pressure sensor with VDD @ 5V
3. a wireless chip with a VDD @ 3V

In order for me to send signals to the wireless chip from the micro; I would need to downscale the voltage 3V instead of 5V.

I was thinking of a voltage divider but for some reason when I attach a load to my micro controller the output voltage drops to about 4.~ volts instead of the usual 5V.

Also, how can I upscale the voltage to 5V when I use it as an input to the micro (5V VDD) from my wireless chip (3V VDD)?

Any insight would be great on this topic. Thanks!

 

[felixc]

If the signals are bidirectional, I have doubts about the reliability of using resistors to match the levels, as the best that you can do with resistors is to offset the 3.3 volt signals to make them fit within the margins of the micro. But anyway you are just making a couple of units.