Do I have Weak Fingers?
Maybe its me but occasionally questions pop into my head that no one else seems to ask. This happened recently when we were talking about map lights found in cars. My car is five years old now and the map light switch is the classical push-to-make/push-to-break switch. The latching action is accomplished with a combination of plastic and springs inside the switch. In more recent or maybe just more expensive cars (note to myself: check the bosses car) the push-button is a very delicate push-button. The latching action has probably been accomplished by a small micro. The implication is that we all want delicate push-buttons with electronic control to replace the firmer push-buttons. This is when that question filtered into my conscious – do I have weak fingers?
Putting that complex question aside for another time I soon realized that F-RAM could be part of a rather neat solution for the weak-fingered applications. The problem with the electronic control is that connecting the vehicle battery after servicing could power up the light in the on state and that could drain the vehicle battery. In the schematic below a Ramtron F-RAM State Saver is used to remember the status. This is a simple D-type latch where the output uses F-RAM to recall the previous state. This means that if the lamp was off before the vehicle battery was removed it will be off after the vehicle battery is reconnected. It doesn’t get much simpler than that. Now, I wonder how to measure finger strength?
F-RAM Design Hints | Duncan Bennett | 
March 29, 2010 12:29 pm
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