I have an Arduino monitoring several sensors (barometric pressure, several temperatures, light, etc.) and sending the results out an XBee to my computer. This works well for about 24 hours, and then things start to deteriorate. The Arduino used to just hang, until I put the watchdog in, and now the Arduino keeping running, but the sensors (mainly the ones on the I2C bus) go though long periods of returning bogus results. My guess is it is probably something about the barometric pressure sensor, but all the problems could be solved by simply resetting all the sensors during the watchdog reset.
The only way to really do this is to shutoff the power supply to everything for a second and bring it back up. The system is currently supplied through a 12V battery charged through a solar cell, and the 12 Volts is fed into a $2 ebay USB car charger power supply based on the MC34063. I was thinking in order to implement a resetting power supply, I would make a power supply using a switching converter that had an enable pin, like the NCP3064, and drive that pin with a 555 setup as a monostable. In the watchdog interrupt, I would just trigger the monostable to shutdown the switching converter for a second, and everything should come up cleanly.
I'm a little worried that this seems a little complicated to do something that is probably pretty common. Is there a simpler way to trigger an full power cycle through the watchdog timer (or an external one)?