Software apps and online services
Hand tools and fabrication machines
This is my fourth project with Arduino.
This device measures the temperature and is self-sufficient from a power supply. It uses a rechargeable battery with 1.100 mAh and 3.7V. With the deep sleep modus of the WEMOS mini it can sustain operation for a period of 10 days.
The WEMOS Mini, the DS 18B20 and the battery shield are attached on a dual shield. In order to be able to measure the voltage, it is necessary to attach a 100 kilo ohm resistor between the positive pole and the input a0 on the battery shield.
Pay attention to the poles of the battery and the battery shield. Sometimes they are swapped.
Please note. Each time a sketch is uploaded, the RST connection with D0 must be disconnected. After the upload of the sketch restore the connection, otherwise deep sleep mode is not possible.
The box is made of a 4 mm thick poplar plywood and cut with a laser cutter. The front and top of the box are not glued for maintenance.
The data are displayed on an e-paper display as well in the BLYNK app. If the battery voltage is low, a warning will be displayed on the e-paper display as well as in the Blynk app. The temperature and voltage are shown in diagrams in the app.
During the charging process, the transmission of the temperature is interrupted because the heat - generated during charging - falsifies the measured value. Even if the voltage is too low, the temperature is not transmitted because the sensor determines incorrect values in this state.
.) operated by battery
.) low battery
.) battery loading
The charging connector is on the bottom of the box.