has anyone used latches as short term memory in control applications and if so how?

Question

Right this is an electronics question and i`m new to this but am developing a computer controlled stepper motor drive system .(had some old printers for parts) and I had this idea to make a plugable system so expansion could become easier as my interest grows and uses are found. The idea is to use latching ics like the jk flip flop to collect data from the bus and set the busy signal until the stepper has done its bit and is ready to move again. This would allow the p.c. to do something more interesting instead while the real world does it`s thing. so the real question is how as all the books i've read dont cover this form of application for that i.c.(or do but i'm not smart enough to realise). so a circuit diagram would be groovy but a very good description may well surfice.

look forward to hearing from you soon bye

Answer 1

Not a bad idea, but you do need to learn a bit more about control systems, bus (and CPU) interfaces, etc.

In the generic 'bus interface', the CPU provides some sort of 'device address' as well as data and a 'write' strobe. Your interface must be able to decode the 'device address' and recognize it as being the address of itself, AND this with the write strobe, and use that signal to either enable a latch or clock a 'J-K' or 'D' flip-flop to hold the data until the rest of your interface can do something with it.

If you're thinking about stepper motors, you might want to look into what are called 'state-machines' and then consider 'registered PAL' logic. These are the usual 'weapons of choice' for smaller bus interfaces and stepper motor drivers.

Another good place to go for ideas is the Microchip website. They have a ton of information on their 'PIC' series microcontrollers and lots of applications literature and notes (including schematics) for stepper motor controllers (among many other things ☺). They're an excellent resource and their parts are both readily available (Digi-Key, Mouser, etc.) and relatively inexpensive.

They also have many megabytes of --FREE-- software (compilers, assemblers, etc. as well as a very slick emulator package with an integrated software development environment) that can be had for the effort it takes to download them.

Drop a line if you want to chat.

Doug