I have been working on a wireless project that uses the Picaxe 28X1 and an Xbee device. The Picaxe being a 5 volt device and the Xbee a 3.3 volt device leads to interfacing problems. This website recommends using a two resistor voltage divider method of interfacing 3.3 volt and 5 volt devices, but it is uni-directional (operates in one direction only). The PicAxe forums also mentions operating the Picaxe on 3.3 volts, which leads to other problems.
I found a neat circuit that uses two resistors and a Mosfet for a bi-directional interface that has been around for ages it seems. The problem using that circuit is that the Mosfet is in an SOT package and is too small for me to solder reliably. After doing a lot of digging I finally found a Fairchild Mosfet that is in a TO-92 package and easily used in through-hole PCBs as well as conventional breadboards and is available here in the states and might be available across the big waters too. The chip is a 2N7000TA.
Here's the interface that I have been using. It is accurate, reliable and usable for us. I thought that I would pass it on to the group.
I found a neat circuit that uses two resistors and a Mosfet for a bi-directional interface that has been around for ages it seems. The problem using that circuit is that the Mosfet is in an SOT package and is too small for me to solder reliably. After doing a lot of digging I finally found a Fairchild Mosfet that is in a TO-92 package and easily used in through-hole PCBs as well as conventional breadboards and is available here in the states and might be available across the big waters too. The chip is a 2N7000TA.
Here's the interface that I have been using. It is accurate, reliable and usable for us. I thought that I would pass it on to the group.
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