manually operated 2 digit up/down counter

I'm with "Telecom" on this one.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

This project screams "synchronous binary counter" aka state machine.

You can implement that easily within one PALx chip. Probably a

22v10 considering the number of outputs youd need

Check out the datasheets for the CD4029 presettable Up/Down counter, and the CD4056 BCD-7 segment decoder-driver. They will do what you need, in addition to giving you the ability to preset a count into the counters. You'll need additional logic to prevent the count from going from 00 to 99 in case of a down command when the count is at 00. Alternatively, a PIC is a very good choice here, but requires a bit of coding to be done. Do whichever is more comfortable for you

--
Dave M
MasonDG44 at comcast dot net  (Just subsitute the appropriate characters in 
the address)

Never take a laxative and a sleeping pill at the same time!!
>

To heck with PICs and programming and incomprehensible instructions, or using a whole big computer!

I suggest using a couple of CD40110BE ICs which are exactly what you want, they are cascadable up-down decade counters with separate up and down inputs, with 7-segment decoder-driver built in. They are not so popular any more but TI still makes them and Digi-Key has zillions (hundreds, anyway) in stock at about $1 each.

You need resistors to limit the current to the CC readouts, and you might need a bounceless pushbutton circuit on the inputs. The latter can be made with an SPDT switch and cross-coupled CMOS inverters, with no other parts needed. You also need a Reset button or else power-on reset.

Hi,

I need to build a 2 digit (00-99) up/down counter.

the system must have an "count up" button and a "count down" button.

when the "count up" button is pressed the counter must add 1 tot it's current amount similar for "count down" ...

somebody is operating the count up, and someone else is operating the count down button, to monitor a production process. Every time an order comes in, a person presses the "count up" button. someone else produces the order, and when ready presses the "count down" button

this way everyone can see how many more oders are "pending" ...

I'm sure there is a simple solution for this, but I haven't found it yet

Please help

Thanks

Pascal

P.S. To reply, remove the "+" from the Email adress

Get an old 386/486 machine running MS-DOS (used to be a few dollars at any thrift store but I think they quit accepting computers this old) and write a quickbasic program to do this function. Have one key be "count up" and another key be "count down."

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Sure did, pretty much in one sitting. I always wonder what interesting stuff the author might have left out for whatever reasons, but that's another story. ;-) Thanks for the pointer.

For the OP:

Here's a slightly arcane fragment of midrange PIC code from Dimitry Kiryashov for increment of a packed BCD number (the PIC does not have a decimal adjust instruction so you have to write code to correct using the DC (digit carry) flag): reg is some arbitrary byte in the current ram bank.

incf reg,F movlw 0x66 addwf reg,F skpndc andlw 0xF0 skpnc andlw 0x0F subwf reg,F

The zero flag is valid at the end so you can use that to indicate when a carry should take place if you have multiple bytes

And for decrement:

movlw 0x01 subwf reg,W skpdc xorlw 0x06 skpc xorlw 0x60 movwf reg

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Search for "up/down counter", or check out PIC's.

Ken

The 40110 idea seems best, and the circuit would look something like this: View in a fixed-width font such as Courier.

common cathode +-CD40110B-+ +---------+ --- | | | | +---o o-+ +---------|RST a|-R---| | | sw1 | UP | | | | a | | | +---+ | | b|-R---| --- | | +--|OS1|---|--------->CKUP | | | | | | +---+ | | c|-R---| f| |b | | +---+ | | | | --- | | +--|OS2|---|--------->CKDN d|-R---| e| g | | | | +---+ | | | | | |c | | --- | DWN | |___ e|-R---| --- | +---o o-+ | +----|TEN | | d | | sw2 | | | f|-R---| | --- | | | | | | /// | +----|LEN g|-R---| | | | | | +----+----+ | --- | | | | /// |BRW CRY | --- | +----------+ /// | | | | | | VDD | +-------+ | | | | | | --- | | +---------+ +---o o---+ | | common sw3 | | | cathode | | | +-CD40110B-+ +---------+ +---+ | | | | | | | +--|OS3|--+---------|RST a|-R---| | | +---+ | | | | | a | | RST | | | b|-R---| --- | | | +-->CKUP | | | | | | | | c|-R---| f| |b | | | | | | --- | | +----->CKDN d|-R---| e| g | | | | | | | |c | | |___ e|-R---| --- | | +-----|TEN | | d | | | | f|-R---| | | | | | | | | +-----|LEN g|-R---| | | | | | +----+----+ | --- | | | | /// |BRW CRY | --- | +----------+ /// | | | | +---------------------+

SW1 UP COUNT MOMENTARY NORMALLY OPEN

SW2 DOWN COUNT MOMENTARY NORMALLY OPEN

SW3 RESET MOMENTARY NORMALLY OPEN

OS1,OS2 DEBOUNCE ONE-SHOTS

OS3 RESET ONE-SHOT

OS1,OS2 DEBOUNCE ONE-SHOT CKTS (2)

VDD | +---------+---+ | | | | +------------LM555 [100K] | VDD RST | | | | | | | | | OUT |-----> output from >--[470]---+---|THRESH | switch | | | +---|TRIG DIS | | | | | | CON | | | | === | GND | 0.47U| +---------------+ | | | | +-----------+ | --- ///

OS3 RESET ONE-SHOT CKT

+----------+ | | --- | /// +-------CD4013 | SET | | | VDD>----|D Q|------+--[10K]--> output | | | | | [100K] from >---------->CK | | BRW | _| | | Q|--||--+ | RST | 0.1U | +-----------+ | | | | | +---[1M]-----+

+---------+ | | | +-------CD4013 | | SET | | | | +---|D Q|- | | | | | | +--->CK | | | _| | | Q|- | | RST | | +-----------+ | | +---------+ | --- ///

For VDD=5V supply make display R=220 ohms, for VDD=12V use R=1K.

Don't tell me you actually *read* the book? :-)

Ken

Glad you enjoyed it. We had a great time on the island, and I had a lot of fun rebuilding a telco. I'm off to Pitcairn Island in a few weeks to look at their infrastructure - fun in the sun! :-)

Anyhoo, many moons ago I built a chess timer based on one of the 74C92x family (I forget which one now), which is essentially the same idea. However by the time you put all the glue bits next to any of these 74xxx family chips to get a display counter going, you may as well use a PIC which can then do 'other stuff' as it is required (and it will be).

One thing I'd be dubious about in an application such as the OP is looking at is what happens when both orderer and picker push a button at the same time, or maybe you want to have several people doing either or each task and therefore increase the risk of simultaneous events. Having done a much larger system (full inventory tracking as well as pick-list functionality), I can appreciate the need for an orderly and predictable handling of such events..

Cheers.

Ken

In the extremely unlikely event the orderer and picker press their switches within 0.0000001 seconds of each other, the result will be that a count *may* not register for one of them but not both. Both users have visual feedback by way of the display, so that the orderer is expecting either an increment or stay the same, and a lost count would mean he/she sees a decrement. My, my, my, ooh and ahhh, what a catastrophe, he/she merely re-presses the momentary. The case of picker expecting either decrement or stay the same seeing an increment is likewise the same.

Ehhh big deal- then each switch registers with a task latch that is sequentially serviced by a simple scan circuit and cleared afterwards- nothing insurmountable there.

IOW, something that is conceptually simple....

.... becomes yet another microcontroller project. ;)

Jon