Hi,
I have an Arduino Uno that will talk to a 3.3V device using serial communication. They will both operate from a 3.7V lithium ion battery.
To be able to use the arduino so that it is not running out of spec, should i boost the battery voltage to 5V and then use a logic shifter (https://www.sparkfun.com/products/11978)?
Is this the best way to handle this?
Thanks
Full charge is 4V+ -> I'd give it a shot and keep it in mind if something doesnt work as expected
That's what i was thinking. But if the voltage drops below 3.7V, say 3.5V, i'm not sure what will happen. On the other hand, i think the 5V boost converters can handle very low input voltages and still give 5V.
..Give it a go, If u experience problems you - reduce clock speed.
What voltage and clock speed would i need so that it may work ok?
At 8 mhz and without crystal you can use an Atmega328p safely at 3.3v (or even lower voltage), this is explained here http://arduino.cc/en/Tutorial/ArduinoToBreadboard . But I don't know if you can reduce the clock speed of a Uno
You could also try a Pro-Mini at 3.3v and feed it through the vin pin.
Datasheet.
Elsewhere in this forum you will fins a discussion.. A user ran the 328P , 16MHz below 3V.
Based on that discussion I believe you are relatively safe @ 3.6V (almost flat cell)
Is it possible to run a standalone ATmega168 circuit from a 3.7V lithium ion battery (voltage varies 3.4V to 4.2V) and then send serial to a 3.3V logic device without any potential problems in the long term?
Add a diode, serial to signals out.
Add a diode, serial to signals out.
Will i be able to send and receive serial data with the added diode?
Arduino 3.3V -> sensor power.
Arduino OUT -> D-anode , D-kathode -> sensor in.
Give you a small voltage drop. (it may be neccesary with a 10k pull_down resistor at sensor input)
Signals from sensor to arduino : direct connections
Thanks for your response.
I drew up your circuit for a standalone ATMEGA168 powered by a 3.7V lipo battery connected to the 3.3V logic serial device.
How does this look?
Thanks
The 3.3V device has its own regulator? Will it work with a 3.4V supply? Or does it need some higher amount to get a regulated 3.3V out?
The 3.3V device has its own regulator? Will it work with a 3.4V supply? Or does it need some higher amount to get a regulated 3.3V out?
The device does have a regulator and it will work fine with this setup.
In terms of the serial communication setup between the Arduino and the device, i was wondering whether it will work ok? (please see attached) Any advice is greatly appreciated.
