EPA III wrote:I have been experimenting with some uCs and I did think of that. But then you have to interface the uC to the display. And displays are not cheap. Microprocessor friendly, serial displays are even worse. I have some seven segment LED displays in my junk box. Oh, and you have to program it too. And debug. And I want switching for several different units of measure.
Let me play devil's advocate. We can discuss your project using
hand written notes, and the US mail. We'd not have to learn
typing and computer skills, own a computer, connect to the
internet, and pay the higher electricity bills.
But the Internet thing is so much better overall, that anyone
reading this post has already overcome the objections and
hurdles noted above.
Same deal with the uC project. Once you have programmed
one chip you are set up to do more, do them different, and
do them well for an unlimited variety of new projects (within
reason).
I have driven twin seven segment displays directly from the
small uC chips, and adding ony two transistors and seven
resistors (which you likely have with combinational logic
drivers).
I have driven multiple alphanumeric displays from a uC with
a few dedicated driver ICs. The power of changing fonts,
special characters, and other manipulations is shifted to
firmware coding.
I've used industry standard LCD modules directly on the
uC ports, with both new and surplus (cheap) LCD modules.
I haven't used the serial LCD modules yet, there seems
little advantage over the parallel variety.
EPA III wrote:I think a hardware solution makes sense here and the 74C926 connects directly to the 7 segments with four transistors and seven resistors (also in my present stocks). I plan to just switch different timing resistors in a 555 timer circuit (got those too) for different ranges. Two chips, four transistors, a rotary switch, and a handfull of Rs, Cs, and Ds and it is done. I suspect it will be half the price of a uC circuit.
A medium size 28 pin DIP AVR uC costs $3.66...
Once you have a processor in your project all that other
glue logic and timers etc. goes away. Complex and
costly rotary switches are replaced by simple switches
or better yet a rotary encoder (digital 'volume control').
The transition is not easy. Some companies that made
analog only test equipment took a long time to drink the
all-digital hardware and software Koolaid.
Should be interestnig to see which path you take. They'e
both valid.