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If you have access to an eprom programmer, it is simple to program in a lookup table.Dagon said:Thanks, I could use the Binary to BCD decoder but I can't figure out how to join them. That is the main problem.
There was a chip, the 74185, but is obsolet, the thing doesn't appear in CircuitMaker.
:?
According to what I can find, the 74185 was a mask-programmed ROM. It wasn't made of logic gates.Dagon said:Thanks for your replies.
Anyone knows how it work the 74185 chip?
What logical gates form it?
Sorry, I can't make lookup tables, I'm a newbie at this.![]()
mbramwel said:an eprom has many input pins and 8 output pins.
think of the 8 output pins as 2 groups of 4. If you were to connect them to a bcd-to-led driver chip, you could drive 2 7segment displays.
if i had to translate it without using any programmable device
and - only to drive display, i would try to think of alternative approach.
something that is easy to troubleshoot... for example, an eye is quite
slow and there is no need to make "instant" conversion (result is for
indication only - not to drive other circuitry that would do some
sort of processing).
so for example, I would use two independant sets of counters
one binary and one BCD, both would be reset together and
both would be clocked together.
the BCD ones would be used to drive 7-seg displays, while binary one
would be used for comparison with input value.
as long as there is no match, simple AND gate would open and clock both counters.
once there is a match, both counters would stop and BCD would display value.
clock speed is not critical. make it faster for faster circuit response...
even with only 1kHz, 8-bit number (256 possible combinations)
would be decoded in only 256/1000Hz=0.256second and this is worst case
scenario. that's about 4 updates per second even for changing input.
that is pretty much as fast as display update on good multimeter but you
can clock it much faster than that. 10MHz clock would make it 10000x faster.
Well, one out of four ain't bad. :?Dagon said:The number comes from an input of 7 logical switches.
It can change, say you want the number 2 the switch #6 would be on.
Ron H said:Well, one out of four ain't bad. :?Dagon said:The number comes from an input of 7 logical switches.
It can change, say you want the number 2 the switch #6 would be on.
(I asked four questions - you answered the first one).
Are the switches manually controlled? What about the supply voltage?