I am looking at the mote schematic for r4. I was expecting to see a level shifter to downshift MOSI, CLK, CS from ATMEGA to RFM69...but I couldn't find one? I *thought* the ATMEGA 328 at 5V (digital pin out) and RFM69 w/ 3.3V in would need one?
Thank you!
Moteino actually run at 3.3V, hence no level shifter is required.
yes. I understand Moteino runs at 3.3V. However, isn't the ATMega328 digital out at 5V? Then MOSI, CLK, CS (going from Arduino to Moteino) would need to level shift from 5 v to 3.3v? What am I missing?
No, it's ALL 100% 3.3V. Atmega can run anywhere between 1.8V and 5.5V. See the datasheet: http://www.atmel.com/Images/doc8161.pdf
Thank you. I apologize for my confusion (and obvious lack of more careful research given my knowledge level).
It's no problem, don't need to apologize.
When I said it's ALL 3.3V that's not entirely correct. The input to the Moteino CAN be 5V. However there's the regulator which brings it down to 3.3V before feeding the atmega and transceiver. Maybe that adds a little confusion to the 5V/3.3V specs.
Thanks for your additional thoughts. I'm pretty sure my confusion was equating the Arduino Uno to the ATMega328p(Yah - I realize how silly that may be!). Whereas the Arduino Uno has digital pins output at 5V (more of a 5V device)....the Moteino sticks to 3.3V