Welcome to EnviroDIY, a community for do-it-yourself environmental science and monitoring. EnviroDIY is part of WikiWatershed, a web toolkit designed to help citizens, conservation practitioners, municipal decision-makers, researchers, educators, and students advance knowledge and stewardship of fresh water. New to EnviroDIY? Start here

Reply To: MS One-Wire Power

Home Forums Environmental Sensors MS One-Wire Power Reply To: MS One-Wire Power

Shannon Hicks

    Onewire sensors like the DS18b20 don’t like to have their bus power cycled on and off.   Back when I last experimented with them (with a different sketch not related to ModularSensors), if you’ve got the sensor connected to the switched power supply, you had to do “DSsensors.begin();” each time the logger woke and powered up the switched power bus.  Only then will the DS18b20 be seen by the Mayfly.  So I just put that command in the loop right after the Mayfly wakes up from sleep.

    The easy solution to this is to just connect the DS18b20 to the Mayfly’s D5-6 Grove jack and put the power-select jumper to “3.3v const”(it’s default position) that way the Onewire sensor is constantly powered and won’t “disappear” after the pin 22 switched power is cycled.  Having a constantly powered Grove jack for I2C and Onewire peripherals is exactly why I designed the Mayfly’s D5-6 jack power selection options.