0
\$\begingroup\$

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!

\$\endgroup\$
  • \$\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
2
\$\begingroup\$

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 | |
\$\endgroup\$
  • \$\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

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.