A small and colourful project to visually and audibly notify that 15 minutes have expired.
This design has not been compliance tested and will not be. If replicated and damage is caused I take no responsibility for this. I accept no responsibility for any damage to any equipment that results from the use of this design and its components. IT IS ENTIRELY AT YOUR OWN RISK!
This project was designed to be used as a "home work" timer for pre-school student without the use of countdown numbers. Rather it simply fades a PL9823 8mm LED from Green through to Red over a period of 15 minutes.
At the start and end of the time period a beeper is sounded.
Prototype:
My design goals for this design were to:
- Have a quickly working prototype which could be immediately used.
- Compact and have the opportunity to be powered via USB or 3 Volts.
For connections, as there are only 3 GPIOs used, refer to the source code for connections. Internal pullups are used where required and this no external resistor were used.
For those wanting to build their own hardware, here is the BOM;
| Reference(s) | Value |
|---|---|
| Micro | ATTiny85 |
| LED | PL9823 8mm |
| Buzzer | Piezo Passive Buzzer |
| Switch | N/O Push Button |
For this design, I used the following open source libraries:
- https://github.com/pkourany/clickButton
- WS2811 RGB LED driver by Alan Burlison, alan@bleaklow.com.
These libraries were modified to work with the ATTiny85 and / or the connected Hardware. Please refer to the updated history of the references sources.