Just to let everyone know...  I'm using a 3DR 900mhz air module with a 3.3V TTL serial cable.  

It's the cheapest Chinese 3.3V TTL cable you can buy and it's working just fine.  I've had some firmware update problems, but those happen on both air and ground modems, so it's not a communication problem with the cable.

I've tested the radio pair both plugged into my laptop and typed back and forth each way through com port terminal windows.

Hopefully this can save someone from having to buy an oldskool 5V FTDI style cable.


I sure wish they had put all the level shifters on the APM2.0 board instead of putting them on everything else.  The processors on the APM2.0 are the only thing still using archaic 5V signaling AFAIK.  The GPS, gyros, accelerometers, Si1000 radio, and everything else I'm aware of uses 3.3V.

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Can you share a link to your cable?

Hi Jake, the 3DR Radios have always worked with 3V3 serial cables. That's how they get flashed during assembly.

IIRC this is my adapter I use...



Suntekstore.com and goodluckbuy.com are some cheap Chinese sources.  Ebay is also usually pretty easy and cheap.


Since it's a 5V interface I thought people would like to know it happens to work with 3.3v also.  The APM is the only 5V microcontroller or IC I ever use anymore, so it's nice that 3.3v works with the radio.

It would have been nice if they put level shifters on all the APM IO instead of putting them on every other device.

So after my post on sensor and imu, can you say me if i can power and interface 3dr radio with 3.3V power and serial signal?

Thank you


You need 5V power for the radio, but you can use 3.3v signal.

OK thank you very much!!



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