Tiny Mdt a Useful Gadget!

Tiny mdt is a small electronic gadget that measures environmental data and shows it on a small 0.96" OLED display. 

The data is acquired and processed by an ATtiny85 microcontroller.

The device is powered by a 3v CR2032 coin cell

the card only works when the power button is pressed and turns off when released.

So most of the time the device stays off, saving energy.

According to my calculations, with moderate use, the battery should last about 10-12 months.

I created the software with Arduino IDE. The big challenge was to find the lightest libraries to fit in the limited memory of the ATtiny85.

The project is available in 2 versions, with the same PCB (only the sensors to be used and the software to be loaded into the microcontroller change):

Type1: HTT

This variant uses the HTU21D sensor which measures humidity and ambient temperature.

Furthermore, the temperature of an object is also detected using the MLX90614 infrared thermometer.

TYpe 2: HTP

This is a small portable weather station in the palm of your hand!

The board uses the excellent BME280 sensor which measures humidity, temperature and barometric pressure.

1. Tiny mdt PCB.
2. You can buy here: https://www.pcbway.com/project/shareproject/Tiny_mdt_a_useful_tiny_gadget_62d95af3.html
3. Or you can download the gerber files from here: https://github.com/Green-bms/Tiny_mdt/tree/master/Kicad/tiny_dt_0/export
4. 0,96" Oled display (suggested: https://www.pcbway.com/project/gifts_detail/0_96_Inch_Oled_Screen.html
5. Push Button
6. 8p IC socket
7. Attiny85 microcontroller (suggested: https://www.digikey.it/it/products/detail/microchip-technology/ATTINY85-20PU/735469
8. HTU21D sensor (only for type 1): suggested link
9. MLX90614 infrared temperature sensor (only for type 1) suggested link
10. BME280 sensor (only for type 2): suggested link
11. CR2032 cell holder: suggested link
12. 3d base (download attached files and print)
13. 3d cover type 1 (download attached files and print)
14. 3d cover type 2 (download attached files and print)

It's a very simple and quick operation! Because the few components that make up the project are all through hole mounting!

Download the Arduino IDe Type1 (tiny_htt_o.ino) or Type2 (tiny_hpt_o.ino) attached code.

Load it into Attiny85 using the programmer you prefere.

If you want you can use this programmer: "Wemos as ISP" that you find here: https://hackaday.io/project/195118-wemos-as-isp

Don't forget that the card only works when the power button is pressed and turns off when released.

So most of the time the device stays off, saving energy!!!