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It can be done with one or two counters. Which do you think will be simpler?
counting from 10 to 0 decimal
- Thread starter le011
- Start date
From the datasheet:
PD: you should capture the screen with the "Print Screen" button, then cut the image and attach it. That image you uploaded before cannot be read.
A logical ‘‘1’’ preset enable signal allows information at the
‘‘jam’’ inputs to preset the counter to any state asynchro-
nously with the clock. The counter is advanced one count at
the positive-going edge of the clock if the carry in and pre-
set enable inputs are at logical ‘‘0’’. Advancement is inhibit-
ed when either or both of these two inputs is at logical ‘‘1’’.
‘‘jam’’ inputs to preset the counter to any state asynchro-
nously with the clock. The counter is advanced one count at
the positive-going edge of the clock if the carry in and pre-
set enable inputs are at logical ‘‘0’’. Advancement is inhibit-
ed when either or both of these two inputs is at logical ‘‘1’’.
The carry out signal is normally at logical ‘‘1’’ state and goes to logical ‘‘0’’ state when the counter reaches its maximum" count in the ‘‘up’’ mode or the minimum count in the ‘‘down’’ mode provided the carry input is at logical ‘‘0’’ state.
So, you need to get the "preset-enable" input temporarily high at power-on, and you can use the "carry out" signal to disable your clock, or if it's only one digit, maybe connecting it to the "carry in" input.
PD: you should capture the screen with the "Print Screen" button, then cut the image and attach it. That image you uploaded before cannot be read.
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This is your data sheet. FIGURE 13. CASCADING COUNTER PACKAGES clearly shows how to cascade two or more counters. The CD4029BMS consists of a four-stage binary or BCD-decade up/ down counter with provisions for look-ahead carry in both counting modes. The inputs consist of a single CLOCK, CARRY-IN (CLOCK ENABLE), BINARY/DECADE, UP/DOWN, PRESET ENABLE, and four individual JAM signals. Q1, Q2, Q3, Q4 and a CARRY OUT signal are provided as outputs.
The count down from a decimal 10 to 0 is 11 counts (10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0). Each counter will require a BCD to 7 Segment display driver. A single counter will only display 9 through 0 which is what you have so you add another counter and display driver. The counters allow a preset (Q1, Q2, Q3 and Q4). There is also a PRESET-ENABLE allowing you to load your preset value. The Function Table in the data sheet shows the logic levels for the function pins.
What part of this are you not understanding?
Ron
The count down from a decimal 10 to 0 is 11 counts (10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0). Each counter will require a BCD to 7 Segment display driver. A single counter will only display 9 through 0 which is what you have so you add another counter and display driver. The counters allow a preset (Q1, Q2, Q3 and Q4). There is also a PRESET-ENABLE allowing you to load your preset value. The Function Table in the data sheet shows the logic levels for the function pins.
What part of this are you not understanding?
Ron
or even from 11..
Does the counter have a feature you could use to cause it to start from 10?
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A high PRESET ENABLE signal allows information on the JAM INPUTS to preset the counter to any state asynchronously with the clock. A low on each JAM line, when the PRESET-ENABLE signal is high, resets the counter to its zero count.
Your PE seems to be tied to Ground? So you are not loading your PE. That's what I see.
Ron
Your PE seems to be tied to Ground? So you are not loading your PE. That's what I see.
Ron
Corrected image from earlier post; missed the fact that you had the A jam input tied HIGH. Also corrected wiring to CI and CLK:
You also have the A jam input tied HIGH on the second counter. Neater wiring might have let you see the mistake more easily.
You also have the A jam input tied HIGH on the second counter. Neater wiring might have let you see the mistake more easily.
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I don't know what is the usual way of doing this, but you can probably use an RC circuit to drive the "preset enable" pins high for an instant during power on. Some ICs don't like slowly changing inputs, so if the ICs acts funny with the RC circuit, add a schmitt trigger gate before the PE pins.
Schmitt trigger inverters coupled with RC circuits can also be used to make an oscillator for the clock signal.
You need to use the "jam inputs" to preset a "1" on the left digit and a "0" on the right digit. Probably defaults to 0, and there's no need to preload that one. Check that.
Schmitt trigger inverters coupled with RC circuits can also be used to make an oscillator for the clock signal.
You need to use the "jam inputs" to preset a "1" on the left digit and a "0" on the right digit. Probably defaults to 0, and there's no need to preload that one. Check that.
This is your homework. Tell us what you've tried. You've already been given a big hint.
You added a gate and a switch and managed to make the schematic hard to read again. Try being neater. In the long run, it will help you and anyone who has to read your schematic.
You've implemented preset backwards and the AND gate is unnecessary.
preset backwards WHATS THAT MEANS?
Preset is HIGH active and you connected them to a pull-up resistor. You should have connected them to a pull-down resistor and have the switch pull it HIGH when it's closed.
In other words, preset is normally not active and is activated by the switch.
OK..I SEE NOW.TY I WILL TRY IT.
WHAT ABOUT THE AND GATE?WHAY IT IS NOT NESSARY?
No good. You still have to activate the switch before the counters can count.
If you want a power on reset, you can add circuitry to do that. This is a common practice because counters aren't guaranteed to power on in a specific state.
