Grove PORT A for both Onewire and i2c sensors

  • Question: Grove PORT A for two sensors, i need to measure temp via 1-wire Ds1820, and Humidity, Pressure etc via i2c ENV II Unit. Someone has tried before? Further, is better use LDO (HT7533 or AM1117-3.3) to power DS1820, to avoid burn input pins (aren't 5V tolerant?). Any other minimal solution? (voltage divider etc).

  • Global Moderator

    @glp you shouldn't use input higher than 3.3v to the IO ports (any IO ports) as it will damage the pins.
    do you plan to use M5Stack sensors or external sensors? if you use external sensors just make sure the output to the pins is not higher than 3.3V

  • @zontex thanks to answer, just to have confirm it is "safe" use a LDO to work at 3.3, i'm planning to connect one ENV II unit and at the same grove port A input pin 32 (or 33) of a Core 2. My doubt came from observe ENV unit schematic, where DHT 12 pin have pullup at 5V. Btw i don't have problem to put a LDO, my goal is share both sensors (one M5Stack and another external DS1820 alt text

  • So, to conclude: Is the Grove port on the Core2 5V tolerant or not? In other words - can I connect a I2C sensor powered with 5V of the Grove connector without level shifter? Also, If the pins are not 5V tolerant, why is then 5V available on the Grove port and not 3.3V?

  • Global Moderator

    @innovationsmaker the esp32 and other microcontrollers such as Arduino are not 5v tolerant, they can sustain a max of 3.3v input into their input pins, there is no voltage regulator on the grove pin to lower 5v to 3.3v so connecting it will damage it.

    The output is 5V because it's delivered by the power management chip and doesn't interact with the ESP32, some sensors require 5V, and its much easy to drop 5V to 3.3V than boosting 3.3V to 5V, most if not all of the M5 Units and sensors support 5V be default so no harm will be caused to them.

  • Maybe it would be an idea to use an I2C to 1-Wire converter? Like the DS2482-100. Then you can have several I2C devices on the bus and also 1-Wire devices. I have not tried the chip yet. But I will do that soon.