Advanced Clock January 2023

In August 2022 my first aquarium started to leak after more than 10 years, therefore I had to order a new one which I designed together with a glass lid. Since my PICclock light control circuit was also getting old, it seemed a good time to develop the successor. During all these years I have collected many ideas on how I would like to improve the PICclock and together with my expanded knowledge I have embarked on a new journey. The only problem is that with greater knowledge, functionality and complexity comes increased development time.

Initial requirements

A list of requirements is huge:

The clock must have an enclosure with all the necessary components to work from line AC power.
A big display with clear and responsive interface controlled using rotary encoder with button.
Linear regulation for custom made LED lights which would allow sun rising and setting simulation and therefore more natural habitat for fish and plants
Measurement of water temperature.
3V battery for clock retention on power loss.
Capable but simple MCU.
Ports for extensions that could be later programmed to turn on/off at certain clock.

A crude block diagrams for power supplies, signals and connectors were drawn and shown in Figures 1, 2 and 3.

Figure 1: Block diagram of power supply composition

Figure 2: Block diagram of signal part of the circuit

Figure 3: Diagram of connectors needed for the project

Circuit design

Usually I would design circuit first and then ordered components and PCB, but this time the process was reversed due to integrated circuit shortage that started during Corona virus spread in 2020. A quick schematic was drawn with all the components connected together and some basic simulation of analog circuits were done, just to see I am not missing components to ensure desired functionality. After ordering components the schematic was drawn and checked. Then layout started to be drawn. I decided to use 4 layer PCB to get better filtering and signal integrity and make routing easier because 2 layers can be then used exclusively for signals.

Project postponement

Due to lack of time and other issues, I had to postpone the project. Status of PCB layout on December 2022 can be seen in Figure 4. Due to this some quick upgrades were rather made to PICclock.

Figure 4: State of layout design of top and bottom layer