FTDI module

  • Hello,

    I purchased an AliExpress FTDI FT232RL USB to TTL Serial Converter Adapter Module. It has a jumper for either 5v or 3.3v operantion. It has FTD1232 marked on the back side.

    It will be hooked up to program a 3.3v Arduino Pro Mini.

    In the 3.3v position, any thoughts on whether I can connect a USB port from my laptop? And will it power the Pro Mini in that position?

    Or do you think I need to provide the 3.3v from the Pro Mini?

    I'm thinking that power from Either the 3.3v Pro Mini or USB will work with the jumper in the 3.3v position.


  • Mod

    I'm not sure what you are trying to do but this is the most common way:

    Connect the FTDI to your computer with an USB cable.
    Set the jumper to 3.3V
    Connect Vcc on the FTDI to Vcc on the Pro Mini
    Connect GND on the FTDI to GND on the Pro Mini.

    The FTDI can not deliver a lot of power though. For most sensors the FTDI is enough, but to run power-hungry stuff such as power amplified radios or servos you'll need a separate power source.

    USB power is 5V so if you want to use that you need to connect 5V to the RAW pin on the Pro mini.

  • So maybe this is why my sketch is probably not working on a 3.3v Pro Mini being powered from the FTDI.

    I'm running the ReadAnalogVoltage sketch in the Arduino Basic Examples. It runs fine on a 5v Pro Mini being powered from the FTDI, outputting the read voltage to the Serial Monitor just fine.

    However, on a 3.3v Pro Mini being powered from the FTDI, the sketch runs but the serial monitor displays gibberish...

    Not enough power going back to the USB from the FTDI?

  • Mod

    Reading the power level consumes almost no power so that shouldn't be a problem.

    Which serial speed are you using? The 3.3V Pro Minis are usually run at 8MHz while the 5V variants use 16MHz. 8MHz is sometimes not enough for high speeds. If you use > 38,400 try lowering the setting. 9,600 is enough for debugging. Don't forget to change both in the sketch and in the Serial Monitor.

  • Speed is set to 9600baud in the Sketch. I have hooked up everything per your original reply. Using 3.3v Pro Mini, and jumper is set to 3.3v on ftdi board. Power is being supplied from USB.

    Still getting garbled data on the Arduino IDE Serial Monitor. If I change the SERIAL Monitor to 4800 baud, I CAN read everything!!

    However, if I leave the Sketch to 9600 baud and change the Arduinio Pro Mini to a 5v unit, and just chang the FTDI to the 5v strapping, everything is readable with the Serial Monitor set to 9600 baud.

    I don't get it.

  • Problem Solved! When compiling, you must select Processor: ATmega 328 (3.3v, 8Mhz). Then the Serial Monitor will be fine at 9600 baud with the 3.3v Pro Mini.