Level shifters or voltage dividers for 5v devices on Due ?

Official Hardware Mega Due
1

I've just acquired my first Due a few days ago, and I've been reading about before starting to use it. Now I'm totally paranoid about blowing the thing up !

My plan is to use the Due to replace the Uno in a self-balancing robot, which has the following devices:

  1. MPU6050 accelerometer/gyro - this takes 3.3V in and out so I think should be fine voltage-wise;
  2. HC-06 bluetooth tranceiver - this takes 3.3V in and already has a voltage divider, so I'll feed it 5V;
  3. L298 based motor driver - takes 5V power and hopefully 3.3V from the Due digital pins will be enough to trigger the inputs;
  4. Hall effect rotary encoders on the motors - these take 5V so I assume they output 5V, so these need to be changed;
  5. SRF-04 ultrasonic distance sensor - takes 5V in (fine) but outputs 5V so needs to be changed.

My main question (other than does this look OK :-[ ) is whether a simple 1k/2k voltage divider to take the output to 3.3V will be sufficient for the encoders and SRF-04 or whether I need a level-shifter to make the Due work ?

Thanks,

David

2

If your board is only powered by the USB cable, you can't output more than a total of 500 mA to power all your sensors/encoders/etc.... If your board is powered by a 9V battery pack thru the jack, you can output a maximum of 800 mA. However it's a better option to power directly your sensors from an AC/DC converter and leave the DUE send/receive command signals to/from the sensors. Therefore, logic level shifters (5V <-> 3.3V) are safer and they are really cheap and easy to use.

3

Sounds good, thanks for the advice.

I use these shields (https://m.ebay.co.uk/itm/16340-Battery-Shield-ESP8266-ESP32-Power-Bank-Supply-Module-For-Arduino-UNO-R3-K/283041174988) with two 16340 cells so I probably get 600mA or so.

I'll order some level shifters :slight_smile: