Abstract: In view of the fact that the reed failure of tipping bucket rain sensor can not be found in time, a tipping bucket rain gauge which can monitor the state of the sensor on-line is designed. The original normally open reed tube is changed to the normally closed reed tube for counting. At the same time, a detection circuit is added to judge the reed state by STM32 minimum system. At the same time, the reed fault information is timely transmitted by the door circuit signal Inform, easy to maintain. The developed tipping bucket rain gauge, which can monitor the status of the sensor on-line, can monitor the working state of the tipping bucket rain sensor in time, which is convenient for the maintenance personnel to arrive at the site for maintenance in time, and fill the gap that the tipping bucket rain gauge cannot monitor the status online in China.

Key words: normally-closed reed, relay, gate circuit, STM32