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Topic: Arduino Pro Mini 3V3 with TTL-232R-3V3 gives 5V (Read 4 times) previous topic - next topic


I bought 10 cables directly at FTDI; TTL-232R-3V3. They all give 5V output for the supply and 3V3 levels for TTL. Could it be that FTDI changed it since than ? I bought them about 1,5 year ago



The cables have always supplied 5v, it's just passed straight through from the usb power lines.

The FTDI chip provides a regulated 3v3 supply on one of its pins. It can only supply a small amount of current so is of limited use.

Different adapters can obviously break different pins out.


This topic refers to a specific product (a cable) from Future Technology Devices International (what a name) or FTDI for short.


The FTDI cables bring out USB 5V to Vcc irrespective of logic level. Another issue to note is that DTR (used for auto reset on Arduino) is not available (they have RTS and CTS brought out).

These cables (the real thing if you like) have been around for a long time, but they've been copied and modified by other companies to meet different requirements. It is somewhat confusing because the 6 pin connector is the same (and they often trade by the same or similar name), but pins to signal mapping is different.

Se, check before buying and make sure you order something that fit your requirements.


Uh-oh -- now I gots the heebie-jeebies about connecting the TTL-232R 3V3 to my Pro Mini.  I also have an FTDI Basic Breakout board that does provide 3.3V, but I'd sure like to use the FTDI cable instead.  Not at the cost of frying my little Pro Mini, however.


You're cool - check the specs from the hardware web page:

Microcontroller ATmega168 -> now 328s actually
Operating Voltage 3.3V or 5V (depending on model)
Input Voltage 3.35 -12 V (3.3V model) or 5 - 12 V (5V model) (on the RAW pin)

Just a slightly different regulator between the 2 parts.
The 8MHz promini will work just fine at 5V as well - check 28.3 of the atmega spec.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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