Here are some of the things I've designed in the past. I'm not going to go into any great depth
but I hope it will give you some ideas or inspiration to try things.
One of the projects I worked on was this cute little LCD clock module. It was designed as a cooker timer and was designed to run off of 2 AA batteries. There was no LCD driver as the microcontroller used was an Atmel 90S8515 (surface mount variety). The various voltages for the backplane and segment drives were derived by a bit of trickery. If an output pin has a potential divider network connected to it (100K to +ve and 100K to 0V) then the output voltage can be +ve or 0V or in the middle. The middle voltage is derived by making the output pin an input thus making it high-impedence and the voltage is then the voltage from the potential divider. Neat. By sending the MCU to sleep and only waking it up whenever the backplane and segment voltages needed to change (and time updating) the circuit could run for months on 2 AA batteries. The LCD driving technique is explained in great detail on various sites across the Internet so I won't go into it here. This particular display was multiplexed and required a quite complex driver program. Simple non-multiplexed displays don't require the resistors mentioned above. The scalpel gives an idea of size. |
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This picture shows another cooker clock. This one is actually an oven programmer and uses a capacitive dropper type supply to reduce mains voltage to low voltage dc. The microcontroller used was a COP8 and this wasn't the kind with Flash memory and so needed an emulator to help in its programming. Thankfully, COP8 emulators are very cheap compared to some MCU emulators. Cooker time was kept accurate by counting mains pulses. |
| This picture is just a close-up of the prototype clock. The display was multiplexed to keep pin count on the MCU to a minimum and to reduce the power requirements. |  |