Arduino MKR1000 output, 3.3 / 5 volts

A stupid question maybe but I have been doing my Googling and still don't understand this.

The Arduino MKR1000 can max tolerate 3.3 Volt into its pins, it can output 5 volts, but I can not use this 5 volts for an MQ-4 sensor, since the returning volts will be too high and therefore damage the pins on the MKR1000?

I read about level shifting, but is there easier solutions? Can I set a regular pin as + 3.3 volts in the code and use it for the MQ-4 sensor? Or can I use the VCC pin as 3.3 volts?

I am planning to connect many low consumption sensors to the MKR1000.

Thanks for all help!

To answer my own question; I have to use the 5 volts output from the MKR1000, but the “answer” from the sensor needs to go through an i2c Level Shifting module 5 - 3v that I can buy on Ebay for a cheap price.

5volt on a MK1000 is not really regulated. It's just USB power (or V-in) with a mosfet switch in between.
Not sure if USB power is accurate enough (±0.1V) for stability of the readout.
It seems that VCC of the sensor is independent of heater voltage, so try to connect sensor VCC to 3.3volt.
Then you won't need a voltage divider (level shifters are digital, so can't be used here).

Thanks for answering Leo.

I just order the Adafruit level shifter: 4-channel I2C-safe Bi-directional Logic Level Converter [BSS138] : ID 757 : $3.95 : Adafruit Industries, Unique & fun DIY electronics and kits but what I really would need if I was using the 5 volt out is a voltage divider?

But anyhow I will try the MQ-4 with the VCC pin :slight_smile:

Isn't i2c open drain? That should mean you can run yor pullups to 3.3v and it won't bother the mkr.

OP is trying to connect an analogue sensor to the MKR1000.
A (digital) level shifter won't work.

Hi westfw, I don't know what open drain means?

This is one of the sensors I plan to use:

It say operating volt 5V. Analog output; the higher the concentration, the higher the voltage. The VCC for the MKR 1000 has 3.3V.

The Level Shift I bought; 8-channel Bi-directional Logic Level Converter [TXB0108] : ID 395 : $7.95 : Adafruit Industries, Unique & fun DIY electronics and kits is not meant for this kind of variable voltage if I understand it correct. It is maybe meant for Pin volt ON and OFF? Is that what you mean with (digital) Level Shifter Leo?

What would you recomend is the best way of connecting this? This is just hobby but it could be fun to make it work as best it can.

The sensor has two internal parts.

  1. the heater, which has to operate at 5volt (± 0.1volt).

  2. analogue measuring part (should be able to run on 3.3volt).