Novelty clock with connectivity.
I always needed a clock with climate sensors in my room, but despite the cheap ones available (including the flippy one from IKEA which my mom uses in the kitchen) I never got around buying one. A while ago I set up a GPS-based Stratum 1 NTP server using one of my spare Raspberry Pi's. Now how about building a clock, with not only climate sensors, but also can receive time over NTP?
The clock needs to sit in my bookshelf. It joins my home network to gain access to the NTP server (or anyone else's over Internet) to pull the time. And maybe it can collect the report the collected climate data to a server.
Thus, here is the design goals:
- Temperature and humidity sensors.
- Have a display to show the current date, time, temperature and humidity.
- Battery-powered device.
- Wi-Fi capable.
I am aware of the ESP8266-based systems, however I cannot keep the wireless on all the time in order not to drain the batteries too quickly. Instead a separate microcontroller is used for the system operation, and the ESP8266 module is on only during the NTP time sync or batched data reporting process.
The overall hardware includes:
- Processor: STM32F103CBT6 or STM32F303CCT6
- Climate Sensor: DHT12
- Wireless Module: ESP-12E ESP8266 based module
- Display: 16x2 HD44780-compatible LCD
- Connectivity: USB for communication and charging, Wi-Fi, Serial and JTAG
This is open source hardware, licensed under the 3-clause BSD license.