This release includes changes to support the new PM sensor batch behavior (zero readings problem), and some other fixes: Fix PM reporting zero on first two readings Needed for old PM sensors: longer Serial timeout, more strict command verification, and clearing buffer Avoid turning off PM sensor on sleep when reading interval is too short Implemented PM passive mode Added PM send command function Added PM send command retry Added PM sensor debug messages PM last reading now uses rtc instead of millis and warmUp as trigger period Empty Serial buffer on getReading to be sure no old data is consumed PM old sensors set passive mode on each wakeUp and add small delay between commands Added Support for external SHT35 Temperature and Humidity sensor Updated some Libraries Some minor fixes in building and flashing script make.py Updated production test code Fix typo on new read interval evaluation Fix disabling urban sensors persistence Fix error on enable/disable PM/PN sensor groups Added Sd card detection debouncing Fix Sanity reset not always triggering Longer (10 min) force publishing every minute period. Full Changelog: https://github.com/fablabbcn/smartcitizen-kit-21/compare/0.9.8...0.9.8-PM To update your kit you can follow this guide, only SAM update is needed.