Are there any dual programmable timers like the CD4541 or HCF4541B - Page 1
Forum section: electronics / projects

author: gilligan
author_rank: Contributor
timestamp: August 27, 2022, 09:51:42 pm
content: I'm looking for a chip that can do essentially what these guys do but with independent on/off duty cycles.So, come on for 10 mins and go off for 120 mins kind of thing.And it would automatically cycle just like these chips can.As to why not just use a microcontroller, because I literally just need to turn one output on and off in a continuous cycle. So a potentiometer to set the on-duty and one to set the off-duty... no need for displays or anything else fancy.Turn it on and it starts cycling.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 27, 2022, 11:30:22 pm
content: you have some projects with the famous 555 or the dual 556 ??

author: gilligan
author_rank: Contributor
timestamp: August 28, 2022, 12:13:25 am
content: I need to be on for at least 10 mins and off for like an hour or so.Maybe as low of an on time as 5 mins and off time as long as 24 hours.

author: MikeK
author_rank: Super Contributor
timestamp: August 28, 2022, 12:41:45 am
content: The CSS555 is a programmable 555. The datasheet says "Delay times from microseconds to days".

author: coromonadalix
author_rank: Super Contributor
timestamp: August 28, 2022, 01:31:49 am
content: https://www.nutsvolts.com/magazine/article/february2016_CSS555TimerICs

author: Zero999
author_rank: Super Contributor
timestamp: August 28, 2022, 08:46:38 am
content: Quote from: gilligan on August 27, 2022, 09:51:42 pmThere are very simple microcontrollers designed for this kind of application.http://ww1.microchip.com/downloads/en/DeviceDoc/ATtiny202-402-AVR-MCU-with-Core-Independent-Peripherals_and-picoPower-40001969A.pdf

author: tooki
author_rank: Super Contributor
timestamp: August 28, 2022, 11:29:02 am
content: Quote from: gilligan on August 27, 2022, 09:51:42 pmYou do realize that you aren’t required by law to attach a display to an MCU? And that practically all of them have ADCs, so you can easily read a pot? Small MCUs will require fewer external components than, say, a 555 timer, which also means the total cost may end up lower than a discrete solution. And you have the added benefit that if your needs ever change and you want a more complex timing scheme, you can just reprogram it?

author: gilligan
author_rank: Contributor
timestamp: August 28, 2022, 12:56:33 pm
content: My only micro controller experience is with Arduino and I don't feel like they are as reliable as I'd want this to be.I mean why do they make the CD4541 if it would be cheaper to just drop in a micro controller?Altronix used these guys and charges a good penny on their 6062 timer boards. I also assume they are sturdy and well trusted, hence the premium price and popularity.

author: gilligan
author_rank: Contributor
timestamp: August 28, 2022, 05:31:51 pm
content: For those talking about "all the additional components" the 4541 requires 3 resistors and 1 capacitor to go from 15 seconds to 10 hours.I would think dropping in a micro controller would require potentially more than that just to function plus the programming... Send like a couple of 4541s triggering each other would be better than a micro controller and probably more reliable.

author: Zero999
author_rank: Super Contributor
timestamp: August 28, 2022, 06:14:38 pm
content: It depends on what you want to do. Modern microcontrollers don't need many external components. Often a decouping capacitor is all that's required. Many MCUs have built-in pull-up resistors and the internal RC oscillator is more accurate than discrete cheap capacitors and resistors.I've not had much experience with MCUs and I'd certainly use one for this project. Here's an example of a simple timer project I made using the old 12F509. It emulates the NE556 and only requires a 100nF decoupling capacitor, the current limiting resistors for the LEDs, a switch and a 3V to 5V power supply. Of course I'd recommend something more modern and if you want it to be adjustable with a potentiometer, then you need an ADC input.https://www.eevblog.com/forum/beginners/my-first-c-program/

author: gilligan
author_rank: Contributor
timestamp: August 28, 2022, 08:24:05 pm
content: But why not just buy an off the shelf product that is purpose designed to do what I'm after.

author: Ian.M
author_rank: Super Contributor
timestamp: August 28, 2022, 08:40:24 pm
content: The market niche such dedicated long period timer chips fell in has been severely eroded by sub $0.50 low pin count MCUs and virtually wiped out by sub $0.10 MCUs like Padauk's offerings, so good luck finding any. If you *DO* find a niche long period timer from an obscure manufacturer, its probably going to be a custom programmed MCU sold at a x10 markup!

author: Zero999
author_rank: Super Contributor
timestamp: August 28, 2022, 09:06:36 pm
content: Quote from: gilligan on August 28, 2022, 08:24:05 pmYou tell me?I'd personally learn more using a microcontroller. Using a dedicated timer chip won't teach you much except for a bit of soldering practise, as most of the parts are in the IC, which just needs to be connected up properly. I can already solder well enough, so it wouldn't gain me any new experience. Using a microcontroller would make me more proficient at using C.If you want a challenge, you could also learn assembly. I did that a long time ago and didn't find it too hard, but I already had some experience, with other CPUs.https://www.eevblog.com/forum/projects/my-first-pic-program/

author: tooki
author_rank: Super Contributor
timestamp: August 28, 2022, 10:29:24 pm
content: Quote from: gilligan on August 28, 2022, 12:56:33 pmSo, the literally billions of microcontrollers in use in essentially every device and appliance made in the last 20-30 years aren’t proof enough of their fundamental reliability?Quote from: gilligan on August 28, 2022, 12:56:33 pmExisting designs, special applications where dedicated hardware is mandated, for fun, …Quote from: gilligan on August 28, 2022, 05:31:51 pmI said:Quote from: tooki on August 28, 2022, 11:29:02 amemphasis added.Quote from: gilligan on August 28, 2022, 05:31:51 pmSounds to me like you’reassuming, not researching.As others said: many microcontrollers today require few external components at all. Some don’t require any whatsoever, especially very small ones.Ultimately, it sounds to me like you want others to affirm your desired approach, not actually explore what’s available.Also, why haven’t you explored the chip manufacturers’ selections of timer ICs? The days of “dumb” timers like the 4541 are mostly over, but nowadays we have much smarter timer/clock generator chips that can do a lot more.And of course, another reason discrete chips are not as popular as in the past is because of FPGAs, which are configurable hardware logic. That gives you the deterministic behavior of bare-metal logic, but with the configurability of a “blank slate”.

author: gilligan
author_rank: Contributor
timestamp: August 30, 2022, 12:32:09 am
content: But a 555 wouldn't fit the bill so I just assumed you were referencing the timer chip that I was specifically talking about in my subject.

author: gilligan
author_rank: Contributor
timestamp: August 30, 2022, 12:34:05 am
content: Also I stated, in the bit you quoted me on, that my only experience is an Arduino and I don't feel like THAT is reliable.Obviously micro controllers are reliable but the more "user friendly" it seems the flakier they can be.

author: tooki
author_rank: Super Contributor
timestamp: August 30, 2022, 06:12:38 am
content: Quote from: gilligan on August 30, 2022, 12:32:09 amI’m not a huge fan of the 555 like so many people are, but it certainly could be pressed into service for this application.Quote from: gilligan on August 30, 2022, 12:34:05 amWhile it’s certainly true that the quality of third-party Arduino libraries varies wildly, the core Arduino code is quite battle tested. Ultimately, reliability is achieved through systematic design and testing, regardless of what foundation you’re using. (Many people say that the libraries from the MCU manufacturers are buggy, too…)FYI, just because TONS of people are unclear about this (including lots of very experienced electronics people): Arduino is really two main things, a simple-to-set-up but simplistic code editor with programmer, and some libraries that provide easier commands for some common operations. That’s it. Beyond that, Arduino is actually just a totally normal* C++ embedded programming environment. Nothing stops you from completely ignoring the “Arduino” commands and talking straight to the hardware.*Exactly three things are different from vanilla C++: 1. It implicitly includes the Arduino.h header; 2. It automatically generates function prototypes; 3. It automatically creates wrappers for the “main” function and a loop within it, calling them “setup” and “loop”. If you take a .ino project and include the Arduino.h header, add function prototypes, and move the setup and loop to main and while(1) and save it as a .cpp file, it will compile.

author: Zero999
author_rank: Super Contributor
timestamp: August 30, 2022, 10:44:42 pm
content: Quote from: gilligan on August 30, 2022, 12:34:05 amHave you considered doing bare metal C programming, rather than Arduino? You might learn a lot more and be able to use a nice cheap 8 pin device, soldered to your own board.If you really don't want to use an MCU, then you're stuck with using two 4541 or CSS555 chips, which I can assure you will take up more space and cost more, when external components are taken into account. There reason why there are no ICs specifically designed for this is because it's much cheaper to use a general purpose microcontroller, which can be made in far greater numbers and is much more flexible.

author: gilligan
author_rank: Contributor
timestamp: August 30, 2022, 11:34:02 pm
content: I'm reading through a tutorial on programming a pic10F200 with assembly right now

author: dobsonr741
author_rank: Frequent Contributor
timestamp: August 31, 2022, 12:34:50 am
content: A recommendation: raspberry pico ($4) with circuitpython. Much more lovable development experience over Pic+assembly.

author: Zero999
author_rank: Super Contributor
timestamp: September 02, 2022, 09:49:52 pm
content: Quote from: dobsonr741 on August 31, 2022, 12:34:50 amIt's often more fun to do it the hard way and you learn more too.Although few people write entire projects in assembly these days, it's still a very good to be familiar with assembly. As far as Python is concerned: I've never used it before and don't see why anyone would seriously consider it for a microcontroller, unless they already know it, but not C and just want it to work.Quote from: gilligan on August 30, 2022, 11:34:02 pmThe PIC10F200 doesn't have an ADC, so you won't be able to use a potentiometer to set the delay. You could use push buttons but it's not possible to program the FLASH during runtime, so the setting will be lost between power cycles.The PIC10F220 has an ADC, is cheaper, the same instruction set as the PIC10F200https://ww1.microchip.com/downloads/en/DeviceDoc/40001239F.pdfThe PIC10F320 supports all the PIC10F200 instructions, plus a few extra, a deeper stack, an ADC and is faster than the PIC10F200.https://ww1.microchip.com/downloads/en/DeviceDoc/40001585D.pdfAnother alternative is the ATiny10, which is even better, but the instruction set is completely different.http://ww1.microchip.com/downloads/en/DeviceDoc/atmel-8127-avr-8-bit-microcontroller-attiny4-attiny5-attiny9-attiny10_datasheet-summary.pdf

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 02, 2022, 09:54:35 pm
content: These days it will indeed be cheaper to do it with a low-cost MCU rather than discrete logic. Almost guaranteed. Sure there will be some time to write the firmware, but for something this simple it shouldn't take long even if you're not familiar with said MCU. The time spent to find a working solution with logic ICs, that areactually available, is likely to be longer.That's a job you could do with a < $0.5 PIC10F/PIC12F or something. Or one of those ATTiny's if you like that better. If you're not afraid of using something largely overkill but only $1, you could also use a RP2040. And then get into the rabbit hole of implementing all kinds of new projects with it, so some learning curve well invested.

author: MikeK
author_rank: Super Contributor
timestamp: September 02, 2022, 10:07:17 pm
content: Quote from: Zero999 on September 02, 2022, 09:49:52 pmThe pot, with a cap, could create an RC delay. No ADC required.

author: Zero999
author_rank: Super Contributor
timestamp: September 03, 2022, 10:00:57 am
content: Quote from: MikeK on September 02, 2022, 10:07:17 pmWith the PIC12F200? How?It doesn't even have a comparator. I suppose it's possible to charge the capacitor by connecting it to an output, via a resistor and monitoring the voltage on the capacitor with an input, but it might be a bit unreliable and one of the advantages of an MCU, is not having to worry about capacitor and resistor tolerances, as the internal RC oscillator is accurate to 1%. Have you done this before?It's much easier to use a device with an ADC input.