I have some 3.3V Arduino Pro Mini boards and they require either an FTDI cable or breakout board to be programmed from a USB port.
So far I've been using a board, but it's annoying to have to either solder headers in place or hold the boards carefully every time I make a modification to the code. Also, switching between 3.3V boards and 5V requires resoldering traces on the FTDI board.
The process goes like this:
– ensure FTDI board is soldered for the correct voltage, resolder if necessary.
– connect FTDI board to arduino pro mini.
– plug mini usb cable into FTDI board.
– carefully hold arduino and FTDI board in place.
– click upload in the Arduino IDE.
Then everything works.
I am aware that FTDI cables don't always support 'auto-reset', but I've never had to manually reset my Arduino in order to load new code.
When does one have to press the reset button if using a cable?
before uploading?
afterwards?
What's the deal here?
Also, can I use a USB FTDI cable to load 3.3V and 5V boards?
Best Answer
I keep one FTDI cable around that I've terminated with breadboard pins for quickly connecting to, well, a breadboard! so I don't have a cable always hanging off my prototypes. I haven't bothered to implement auto-reset; I just use a reset button on the board. The timing that almost always works for me (in Eclipse) is to hold the reset button and release it just as I click Eclipse's download button. (Maybe someday I'll make a tiny PC boards to arrange all four pins into a pseudo BB-plug....)
This cable came with NerdKit AVR kit that was 5v based. So are my BB designs, currently. The FTDI head is on the USB-A male end; I just measured the BB end at 5.09v with no load (except, obviously, the meter). I think you only need to provide the appropriate regulator - 3.3v or 5v - as long as the input to it is higher than that (within reason). I power BB's with a 9v battery when I'm not using the cable.