Post by thread:[EE]: 74LS164/clock design

On 23 May 01, at 20:01, Jinx wrote: > I recently made this display > > http://home.clear.net.nz/pages/joecolquitt/2wireled.html > Oh my God ! I like your pcb's ! Intersting design Joe ! I must upgrade my site too, with my 3 wire driven display with Romanian CMOS chip MMC22925 or MMC22926 It's like yours except bcd/7seg is done internally and can be cascaded Cheers, Vasile -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Intersting design Joe ! I must upgrade my site too, with my 3 wire > driven display with Romanian CMOS chip MMC22925 or > MMC22926 hmmm, don't know those > It's like yours except bcd/7seg is done internally and can be > cascaded The one I'm working on now I thought would use 4017s as the digit select but after a little work it looks as though I'l just cascade two 164s (16 bits for 4 data and 12 digit selects) and replace transistors with ULN darlington drivers. Costs about the same, tidier and will still be two-wire -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Howzabout - MM5450 / 525x 2 wire 32 to 34 segments depending on variant. Settable segment current No drive resistors needed. Non Multiplexed Can do extra segments with multiplex (eg 62 segments with 1 or 2 transistors plus IC. Ye Olde tech but a goodie. {Quote hidden}> > Intersting design Joe ! I must upgrade my site too, with my 3 wire > > driven display with Romanian CMOS chip MMC22925 or > > MMC22926 > > hmmm, don't know those > > > It's like yours except bcd/7seg is done internally and can be > > cascaded > > The one I'm working on now I thought would use 4017s as the digit > select but after a little work it looks as though I'l just cascade two > 164s (16 bits for 4 data and 12 digit selects) and replace transistors > with ULN darlington drivers. Costs about the same, tidier and will > still be two-wire -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

>I like your pcb's ! Thanks, I've just added a component overlay diagram to the zip -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Howzabout - > > MM5450 I looked at this, nice chip. Problem. It's marked for deletion by NatSemi and currently stocks around the place are the big fat 0. RS have them for $25. At that price they can keep them. There are others but cobbling your own out of the bits drawer is more fun -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

I bought a couple from digikey. I thought they were around $5. Ron Jinx wrote: {Quote hidden}> > Howzabout - > > > > MM5450 > > I looked at this, nice chip. Problem. It's marked for deletion > by NatSemi and currently stocks around the place are the > big fat 0. RS have them for $25. At that price they can keep > them. There are others but cobbling your own out of the bits > drawer is more fun > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> I bought a couple from digikey. I thought they were around $5. > Ron Thanks, but you can imagine the fuss to get them to NZ. Awful exchange rate, P&P, tax, god knows what else. I already have ULN2003s so it's a no-brainer -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Jinx wrote: Actually it was Russell who wrote > > > Howzabout - > > > MM5450 > > I looked at this, nice chip. Problem. It's marked for deletion > > by NatSemi and currently stocks around the place are the > > big fat 0. RS have them for $25. At that price they can keep > > them. There are others but cobbling your own out of the bits > > drawer is more fun Farnell have them for $NZ16 in tens = $US7 or so. Considering this is a 34 digit driver that's fairly reasonable. Also an LCD version available. ONE IC (albeit a large one). NO other support parts up to 34 segments (or a couple of resistors for current level set). 2 wire drive. Non multiplexed. No timing constraints - drive easily from eg parallel port or any micro. Minimal extra parts to double (or triple or quadruple) the capacity with multiplexing. A truly excellent device (bodacious even) whose day appears to be gone - now replaced by less capable parts :-) RM -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Farnell have them for $NZ16 in tens = $US7 or so. > A truly excellent device (bodacious even) whose day appears > to be gone - now replaced by less capable parts :-) > RM "I" hear what you're saying. The Scottish tinkerer in me doesn't -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Why not design a clock using a PIC ? Or two PICs ? Why do you need a shift register ? Peter -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Think of the '164 as an I/O expander. Douglas Wood Software Engineer spam_OUTdbwoodTakeThisOuTkc.rr.com Home of the EPICIS Development System for the PIC and SX http://epicis.piclist.com {Original Message removed}

> Why not design a clock using a PIC ? Or two PICs ? Why do you > need a shift register ? For that particular job I needed 4 x 4 digit displays. Portb can handle the lot. In fact, although I still had a4 left over, if I'd needed to claw Portb pins back the s/w could probably have driven all the CP lines with one pin and four others for data. That's not bad, 5 pins for 112 segments -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> the CP lines with one pin and four others for data. That's not > bad, 5 pins for 112 segments To be even more frugal - one pin clocks the display 164s, one pin outputs data to one or more "data 164" (which feed the display 164s with data), a third pin clocks it. Possibly one pin for BI on the 4511 if ghost segments are a problem. That's at least 8 x 4-digit displays using just 3(4) pins at an acceptable refresh rate. Latches could be used to fix the brightness if necessary -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> 112 segments on 5 pins And you could have used a single 16C64 or F877 with two ULN2803A to drive the lot (with common cathode). Peter -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

> > 112 segments on 5 pins > > And you could have used a single 16C64 or F877 If I had any instead of tubes of F84/F628 -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body