Does this kind of counter IC even exist?

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GoingFastTurningLeft
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Post by GoingFastTurningLeft »

That's what I had in mind and why i wanted to use an asychronous 4-bit up/down in the first place, which apparently doesn't exist.
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MrAl
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Post by MrAl »

Hello again,

If you want to use an async counter use a sync counter and clock
it the way you would clock an async counter. There is no problem
here. You provide the clock, it counts up or down. The 74192 if
i remember right will do this.
On the other hand, do you need the preset function since you can
clock it once per gear shift anyway? What is there to preset?

You start from neutral (switch=0) with the counter reset to 0 on
power up. You shift to first gear, the comparator detects the
gear is greater than the counter output, so you clock up one time
and pulse the 'up' game gear. Now the comparator detects there
is no difference between the gear switch (1) and counter (1) so it outputs
an equals "=" so you dont pulse anything.
You shift to second gear and the comparator detects the gear is
greater than the count, so you pulse both counter and game gear
again.
You shift to third, then to fourth, with the same actions occurring.
Each time when the gear switch equals the counter output there
is no further pulsing.

Now you downshift to first gear (if you dare). The gear switch outputs
a binary 1 (one) and the counter is at binary 4, so the comparator
outputs a 'less than' signal. The less than signal pulses the counter
down one count and also pulses the game gear down button. Now the
count is at 3 and the gear switch is still at 1 and the game gear is also
at 3, and the comparator still outputs a 'less than' signal so you pulse
both the counter and the game gear down again. Now the count
goes to 2, and the comparator still outputs 'less than' so you pulse
the counter again and the game gear down again, and now the
count goes to 1 and the game is at 1 and the switch is still at 1 so
the comparator output goes back to equals "=" so no more pulses.

Shifting 'up' by more than one gear at a time (say from first to third)
does the same thing only pulses the counter up one at at time instead
of down and same with the game gear.

In no case did we need to preset the counter, but it did need to be
reset to zero at power up.

Seems to work ok without any preset for the counter...which means you
can use any counter you wish that will go up and down.
LEDs vs Bulbs, LEDs are winning.
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GoingFastTurningLeft
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Post by GoingFastTurningLeft »

The preset is important because I might start the race in 2nd or 3rd gear depending on the gearing for that track, or i might go into the pits in 4th gear and it'll automatically put it in 2nd coming out.

But doesn't what you described pretty much what I designed anyway?

BTW, this game i have in mind has no neutral like you'd have in an automatic car. Holding down the shift button puts it in neutral, you let go of the button and you're at the next gear. So, the actual shift pattern is R-N-1-N-2-N-3-N-4, as it would be in any mt car.

At this point I'm just going to have to mess around with a sync counter i have lying around and attempt to make a circuit block that makes it behave like I want - Up pulse = up, down pulse = down.
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MrAl
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Post by MrAl »

Hi again,

Ok, no problem...

The 74LS193 comes to mind because it has a preset function.
There is no problem clocking this counter in what you might
call async mode, although it actually clocks in sync mode your
circuit will never know the difference.

From what you are saying, the game starts out in some gear?
This wasnt clear from your previous posts. In other words,
does the game start out sometimes in first gear and sometimes
in second gear?
If it starts out in say first then yes you need to preset the counter
to a binary 1.
This isnt hard to do...simply wire the output of the 8 to 3 line encoder
to the preset inputs and have a button you press to toggle the
preset line to the counter. This will load the counter with the correct
binary count to start out with. This assumes your game is already
in that gear too.

Could you clarify this:
Does the game start out in first gear, second gear, or neutral?

You are very close to a solution now.
LEDs vs Bulbs, LEDs are winning.
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