Timeline for How can i make my mod 10 up/down counter wrap from 0 to 9 when counting down?
Current License: CC BY-SA 4.0
24 events
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| Sep 16, 2019 at 2:53 | comment | added | jonk | @Xaero No problem. Your approach wasn't clear to me. And I only offer answers that are designed for a broad audience and not necessarily only the OP. I'm happy with my addition and hopefully it may help others. I'm sorry it didn't work for you. | |
| Sep 16, 2019 at 2:44 | comment | added | Xaero | @jonk thanks jonk for all the help but at the end of the day i really just wanted to get my own circuit to work. I know all i need to do is fix my reset logic even though using it is bad. I will carry on by myself. The 0-99 counter is for another question not this one. | |
| Sep 15, 2019 at 6:10 | comment | added | jonk | @Xaero If you chain up two of them you'll need a ripple carry out and probably an "enable" input, as well. These are found in the 74160-74163 devices. You should examine their logic. | |
| Sep 15, 2019 at 1:34 | comment | added | Xaero | I should mention that because everyone in class was finding it hard to make a counter 1-99. A 0-99 will be accepted and bonus points for anyone with a 1-99. I really wanted to work on a solution myself that's why i just wanted to make a decade counter using reset logic. I figured if i had a working 0-9 up/down counter i could combine two of them and get a 0-99 counter. I am not very comfortable with asking for outside help, but my tutors have given me nothing. Just vague responses like, there is something wrong with the reset logic. | |
| Sep 15, 2019 at 1:25 | history | edited | Xaero | CC BY-SA 4.0 |
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| Sep 14, 2019 at 19:01 | comment | added | jonk | @Xaero First off, it looks like the assignment says 1-99 and not 0-99. Second, you've changed the question, now. Implementation will require 7 TFFs and a different set of tables to work out the logic if you want to do this all in "one go." Alternately, you can do what is done in the 7400 series devices, which is to break this into two pieces, each the same, but provide a ripple clock (which behaves a little differently depending on count direction) so you can chain two of them together. | |
| Sep 14, 2019 at 17:39 | history | edited | Xaero | CC BY-SA 4.0 |
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| Sep 14, 2019 at 17:35 | comment | added | Xaero | @jonk i am very willing to download it and simulate it. You are right that this task has been a very tedious task to do myself. I was given this task only 3 weeks into the course and the only reason why i even know what a decade counter is, is because i have been looking up circuits that can help me with another task. I have updated the main post to show you what the whole task is. I am so grateful for your help with this | |
| Sep 13, 2019 at 6:29 | comment | added | jonk | @Xaero Would you be willing to download and install Neemann's DIGITAL program? It's much better than Logisim (my opinion.) If you decide to do so, you can then also download this example to test out which simulates this schematic. The point of all this is that it sounds like you have been asked to guess your way forward -- like "hunt and peck." But haven't been provided a good process to get from the beginning to the end. | |
| Sep 13, 2019 at 6:03 | comment | added | Xaero | I can follow the logic its just the whole concept to me is new as i have never seen or used tables like what you wrote to plan out a circuit. I am currently working on the circuit again. I will update on my progress soon. Your help has been great | |
| Sep 13, 2019 at 5:51 | comment | added | jonk | @Xaero Where do you find yourself first getting stuck reading what I wrote? For example, when looking at the wide table I provided, do you find the ideas there difficult? Or is it pretty obvious to you how I laid out the table? The excitation columns are simply 1 where the bits changed and 0 otherwise. I hope you can see that much easily enough. (I also included the illegal value rows and used x to indicate 'don't care'.) | |
| Sep 13, 2019 at 5:45 | comment | added | Xaero | Basically all i have been taught in my computer systems course are basic flips flops, registers and ripple counters. Nothing about k maps or any way to plan out a circuit. Just the very very basic fundamentals of using Logisim. All the info you have given me has helped me understand more and i will give it another try | |
| Sep 12, 2019 at 19:18 | answer | added | jonk | timeline score: 2 | |
| Sep 12, 2019 at 15:58 | comment | added | user57037 | Step 1: validate the logic very carefully at schematic level: Step 2, validate the actual wiring very carefully in the prototype. Pro-tip make sure you have capacitors on all IC's in your prototype placed close from VCC to GND. We can't help with step 2, really, but if you post a photograph of your actual circuit, someone might notice something or have some useful suggestions. | |
| Sep 12, 2019 at 15:01 | answer | added | Cristobol Polychronopolis | timeline score: 0 | |
| Sep 12, 2019 at 13:16 | comment | added | jonk | Have you examined the 74169 or 74191 schematics, for example? Your situation is simpler. In any case, you've only told me what you don't know how to use (k maps for example) but haven't told me what you do know about. So all I can do right now is use ideas you say you are unfamiliar with. A waste of both our times. I need to know what mental tools you do have to apply here. | |
| Sep 12, 2019 at 10:28 | comment | added | Xaero | I'd like to say I've made progress but i haven't. I noticed every Q' output is on when the counter is at 0000 and that when it wraps back to 1111 all Q outputs are on instead. I know i can do something with that i just cant figure it out how to wire it right. | |
| Sep 12, 2019 at 7:22 | comment | added | jonk | Well, the idea of laying out the starting value and the next value, listing what changes between them, is one approach that "just works." It's not the only approach. You should use what works for you and since I don't know what you don't know, it is hard for me to suggest a direction. I was only hoping. Best is to use what you do know. So feel free. And if you have an idea, that's good! | |
| Sep 12, 2019 at 7:12 | comment | added | Xaero | @jonk One idea that comes to mind is using a NAND gate to act as the input of the first FF. I will play around with NAND gates some more, i have some idea on how to proceed now. I wont need to change anything with my direction change will I? Also the K-map tables are something i have not learnt and are a hard to follow | |
| Sep 12, 2019 at 6:06 | comment | added | Xaero | Can't i achieve the same thing with what i already have though? I have made another one with parallel inputs but that one has other problems. i.imgur.com/KYFxBKy.png | |
| Sep 12, 2019 at 6:03 | comment | added | jonk | Why not look through this 4-bit counter example and this simple counter example, for starters. Might provide some ideas. | |
| Sep 12, 2019 at 5:09 | comment | added | analogsystemsrf | you need a counter with 4-bits of parallel inputs, those bits used to initialize the FF values upon a LOAD event. | |
| Sep 12, 2019 at 3:45 | review | First posts | |||
| Sep 12, 2019 at 5:32 | |||||
| Sep 12, 2019 at 3:41 | history | asked | Xaero | CC BY-SA 4.0 |
