So, I am currently working on interfacing a MSP430G2553 and an I2C proximity sensor VL6180X. In order to have consistency in my voltages and hardware design, i choose this I2C device from polulu (https://www.pololu.com/product/2489), that offers level-shifting for I2C pins. For now, everything works well with I2C communication only.

The VL6180X sensor has a GPIO1 pin that can be configured as an interrupt request output. I'd like to connect GPIO1 to my microcontroller and use this function, so that I don't have to poll the sensor for results data.

The GPIO1 pin is not level-shifted, according to the documentation. I tried to make it work by wiring it directly to the micro, but I did not get it to work (maybe I did not try enough).

I am wondering, as my pin is providing 2v8 high level, do I need to level shift it for connection to my 3.3V MSP430 ? If so, what is the smallest circuit that can do this?

Thank you in advance!

  • \$\begingroup\$ The GPIO1 output is open-drain as an interrupt output. Have you connected a pull-up resistor between GPIO1 and 2V8, as per the datasheet? They recommend 47K though I'd use anything to hand from, say, 10K to 47K. Your microcontroller may have a programmable pull-up resistance on it's input I/O pin but this will pull up to 3V3. That isn't disastrous, as the sensor pin will probably clamp what it sees as excessive voltages, but the external resistor is better. \$\endgroup\$ – TonyM Dec 4 '17 at 9:21
  • \$\begingroup\$ The VL6180X from polulu already provide a 47K pull-up, as you can see in the schematic @ pololu.com/product/2489. \$\endgroup\$ – Bibindoum Dec 4 '17 at 9:29

At 3.3 V, the MSP430G2553 requires at most 2.475 V to see a high level:

MSP430G2553 Schmitt-trigger inputs

So it should work directly (as long as you are using the correct polarity).

| improve this answer | |
  • \$\begingroup\$ I might have missed something in my configuration when i wired it directly then. Thank you very much ! \$\endgroup\$ – Bibindoum Dec 4 '17 at 9:56

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