![]() What we need to do is reduce this voltage to somewhere between 2.4v and 3.3v. When the FTDI adapter transmits a '1' it sends its output to 5v. We don't have to worry about the '0' case because the Tx output is 0v-5v so a '0' is going to be 0v whatever happens. The output from the FTDI adapter is 0v and 5v for '0' and '1' respectively. The microcontroller input will register a '0' if the voltage is below 0.5v and it will register a '1' if the input voltage is greater than 2.4v. We will deal with the 5v TX from the FTDI adapter driving the 3.3v microcontroller input first. First there is the 5v Tx driving a 3.3v input and there is also the 3.3v Tx driving a 5v input in the opposite direction. Three resistors and a couple of cuts in the copper traces.īefore we start soldering components indiscriminately onto the board it would be a good idea to first do a little design work. Thinking that this might not be the only time that such a little circuit might come in handy I thought that I would build it onto a little piece of copper stripboard to make it easier to use. So I decided to use a simple level converter using a few resistors. This project needed doing and it needed doing now! ![]() I felt stupid for not checking the listing properly before ordering but I was stuck with it and no time to wait for an alternative to arrive. Not wanting to blow up my Pro Mini I checked the FTDI board only to realize that I had bought a 5v unit and not a 3.3v version. It was pretty easy to find so popped one into my shopping cart together with an FTDI adapter so that I could talk to the serial port on the Pro Mini. I needed a low power microcontroller for a project so I headed over to Amazon to look for a 3.3v Arduino Pro Mini compatible board. ![]()
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