I am looking for a device which I do not know exists.
I would like to store the state of a number of analog switches, perhaps driven by a D Type Flip Flop.
I'd like to drive the flip flop and set values with a momentary toggle switch.
What I am looking for is a type of analog switch, which could store memory and survive power downs without relying on some sort of constant power source like a small battery. Basically a parallel accessed EEPROM with direct access to each of the bits through a single pin, or something that behaves in a similar fashion.
Can anyone think of a solution to this problem? Does something like this exist? My research came up with bistable multivibrators, but I could not find information that indicates if those would survive a power down or not. Cost and size are of concern to the design, of course.
Best Answer
The easiest solution by far is going to be to use a microcontroller with built-in EEPROM and some analog switches.
For example, you could use a micro with a hardware SPI interface and 16 MAX335 analog switches. There are many small micros you could use. Something that supports your digital supply and has on-board EEPROM would be simplest. You should also make sure it has a good reset circuit or provide an external one.
When power is applied, or is interrupted, the micro resets, reads 16 bytes of data from the EEPROM and shifts it out to the serially controlled switches.
You can also get crosspoint switches which may be easier to use, if that is your end goal.