Embedded hardware solutions are always project specific.
Here are some different hardware solutions that are used for a number of my projects.
A velomobile board computer
An LPC1754 based custom board controls not only the front and tail light but also includes blinker LEDs, an LC-Display and a wireless tranceiver to communicate with speed sensor, an SRM power meter and a heart rate strap.
This makes it more than just lighting control; a completely integrated board computer that controls all electronics and monitors the engine status.
LPC1754 Target Board
As I was working on the specification for my Velomobile Board Computer, there were a few hardware requirements that were more or less clear: an lpc17xx controller, (micro)-SD card, EEPROM, battery backup, USB connector and ... I needed more I/O lines than available on the standard LPCXpresso modules.
But there were still a lot of hardware issues to be resolved. Reason enough to create a universal target board.
The PCB for the design was made by EuroCircuits. 10 boards were delivered in June 2011 and 3 of those board have been soldered by hand and after two small modifications (2 pins swapped on the micro-SD connector and the pull-up resistor on the USB plug) all of these boards are working OK. Actually I made one more (big) mistake; there is no JTAG connector on the board and I now need to connect a non-standard cable to the IDC header (which is not mounted on two of the freshly assembled boards)