Scrap the 4017 idea. I've decide I'm going to run a 4-Bit counter into a 4-to-16 decoder.
Simple Clockable Decoder Chip
Started by ●May 3, 2008
Reply by ●May 4, 20082008-05-04
Reply by ●May 4, 20082008-05-04
On May 4, 11:24 am, Hans-Bernhard Br=F6ker <HBBroe...@t-online.de> wrote:> rickman wrote: > > Let's face it, if this were a commercial project, you would just pick > > a larger MCU and be done with it. > > I wouldn't, and precisely _because_ it's a commercial project. Hobbyist > or one-off in-house projects often have virtually no cost constraints. > It's the commercial ones that do. > > > Of course if you are making a > > million of them a larger CPU is likely more expensive than a 4000 > > series chip. > > Exactly. And below a million pieces, some might not consider it a > commercial project ;-)Obviously you only work on one type of commercial project. Mine are mostly space constrained. I don't have the luxury of using large package devices where I can do the job in a much smaller part, no matter how many I am building.
Reply by ●May 5, 20082008-05-05
Tomás Ó hÉilidhe <toe@lavabit.com> writes:> The only problem though is that I need a chip that will count to 16 > instead of 10. Does anyone know of a similar chip that will cycle thru > 16 different outputs?Sure, a CPLD. Xilinx XC9536 (5V) or XC9536XL (3.3V) come to mind.
Reply by ●May 5, 20082008-05-05
On May 5, 9:33=A0pm, Eric Smith <e...@brouhaha.com> wrote:> Tom=E1s =D3 h=C9ilidhe <t...@lavabit.com> writes: > > > The only problem though is that I need a chip that will count to 16 > > instead of 10. Does anyone know of a similar chip that will cycle thru > > 16 different outputs? > > Sure, a CPLD. =A0Xilinx XC9536 (5V) or XC9536XL (3.3V) come to mind.Too expensive. As I said elsethread, I've decided to run a 4-Bit counter into a 4- to-16 decoder.
Reply by ●May 6, 20082008-05-06
Tomás Ó hÉilidhe wrote:> As I said elsethread, I've decided to run a 4-Bit counter into a 4- > to-16 decoder.That will work fine, as long as you don't mind the decoding glitches.
Reply by ●May 6, 20082008-05-06
On May 6, 8:10=A0am, Eric Smith <e...@brouhaha.com> wrote:> Tom=E1s =D3 h=C9ilidhe wrote: > > As I said elsethread, I've decided to run a 4-Bit counter into a 4- > > to-16 decoder. > > That will work fine, as long as you don't mind the decoding glitches.Decoding glitches? Please explain.
Reply by ●May 6, 20082008-05-06
On May 5, 5:12 pm, Tom=E1s =D3 h=C9ilidhe <t...@lavabit.com> wrote:> On May 5, 9:33 pm, Eric Smith <e...@brouhaha.com> wrote: > > > Tom=E1s =D3 h=C9ilidhe <t...@lavabit.com> writes: > > > > The only problem though is that I need a chip that will count to 16 > > > instead of 10. Does anyone know of a similar chip that will cycle thru=> > > 16 different outputs? > > > Sure, a CPLD. Xilinx XC9536 (5V) or XC9536XL (3.3V) come to mind. > > Too expensive. > > As I said elsethread, I've decided to run a 4-Bit counter into a 4- > to-16 decoder.What is your cost limit? CPLDs are pretty cheap. I want to say I have seen devices for around a dollar US. Even obsolete logic chips aren't much cheaper than that. Is this intended to teach you something? If so, I would *require* you to use a CPLD if I were the instructor. There is very little value in learning to use chips that were designed long before the PC. Does your instructor also ask you to use a dial phone? Do you connect to your computer using a TTY? (do you know what a TTY is?) Rick
Reply by ●May 6, 20082008-05-06
On May 6, 6:24 am, rickman <gnu...@gmail.com> wrote:> On May 5, 5:12 pm, Tom=E1s =D3 h=C9ilidhe <t...@lavabit.com> wrote: > > > On May 5, 9:33 pm, Eric Smith <e...@brouhaha.com> wrote: > > > > Tom=E1s =D3 h=C9ilidhe <t...@lavabit.com> writes: > > > > > The only problem though is that I need a chip that will count to 16 > > > > instead of 10. Does anyone know of a similar chip that will cycle th=ru> > > > 16 different outputs? > > > > Sure, a CPLD. Xilinx XC9536 (5V) or XC9536XL (3.3V) come to mind. > > > Too expensive.$1.07 qty 1 at digikey: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=3D122-1385-= ND> > > As I said elsethread, I've decided to run a 4-Bit counter into a 4- > > to-16 decoder. > > What is your cost limit? CPLDs are pretty cheap. I want to say I > have seen devices for around a dollar US. Even obsolete logic chips > aren't much cheaper than that.Only if you can find them.> > Is this intended to teach you something?The idea is to teach him what not to do in real life. In real apps, we would not be constrainted to a 20 pins PIC. All his logics can be replaced with a 44 pins uC for 50 cents.> If so, I would *require* you > to use a CPLD if I were the instructor. There is very little value in > learning to use chips that were designed long before the PC. Does > your instructor also ask you to use a dial phone? Do you connect to > your computer using a TTY? (do you know what a TTY is?) > > Rick
Reply by ●May 6, 20082008-05-06
On May 5, 5:12 pm, Tom=E1s =D3 h=C9ilidhe <t...@lavabit.com> wrote:> As I said elsethread, I've decided to run a 4-Bit counter into a 4- > to-16 decoder.In what way is that superior to daisy chaining two shift-register type devices? The only justification I see is if you either also have a use for the binary coded count, or you have those two parts in your junk box and don't have a pair of the others, or something similarly out-of-band (like a different logic family that doesn't include that function, whatever)
Reply by ●May 6, 20082008-05-06
On May 6, 9:24 am, rickman <gnu...@gmail.com> wrote:> Is this intended to teach you something? If so, I would *require* you > to use a CPLD if I were the instructor. There is very little value in > learning to use chips that were designed long before the PC. Does > your instructor also ask you to use a dial phone? Do you connect to > your computer using a TTY? (do you know what a TTY is?)If there's a part available off the shelf for 10 cents, that's likely going to beat the programmable logic solution in most cases. Where it won't is if you don't have those, or don't want to stock them, and go through small CPLD's like jelly beans. Then the cost of programming the CPLDs might possibly beat the cost of inventory. Or if the 10 cent part (or pair of them) won't do the whole job. If you need the CPLD anyway, then this function is no longer the justification for it. But usually, if you can buy your whole solution, it's better to do that than make a custom one. And for that reason, a lot of old technology chips survive, albeit in often in smaller modern packages. There's just no reason to drop them. Rotary dial phones? They had some real issues (finger hurt really badly trying to win radio station call in prizes). TTY? Well, I use software emulation of one almost every day... that basic idea is sound, but printing on paper isn't usually needed.