Function/Reset pushbutton

STM6519?

There look to be others. You could also use a microcontroller, perhaps.

Best regards, Spehro Pefhany

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A 10 second RC is not unreasonable. A 10 uF ceramic cap and a meg or two. 10 seconds sounds a bit much, maybe.

But I bet most gadgets do it in software, so it's not a truly hard reset.

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Thanks, that's exactly it.

MCU is just another part that has to be programmed and tested. And it is prone to hangups, too.

Vladimir Vassilevsky DSP and Mixed Signal Designs

One could use an 8-pin (or 6-pin) processor whose entire job in life is to generate that reset pulse. That would at least minimize the number of lines of code for a bug to hide in.

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On a sunny day (Thu, 11 Apr 2013 21:38:24 -0500) it happened Vladimir Vassilevsky wrote in :

I have that as some extra code in the PIC, for example in my gamma spectrometer, 10 seonds push on the red button wil power it down,

10 seconds to prevent accidently switching it off. The PIC does a lot more, but for simple cases a PIC (with internal osillator) may even be cheaper than some RC stuff, and certainly more accurate (2%). And it can drive LEDs and other things too, current consumption in the uA range. More keys (gamma spectrometer has 18 push buttons), all in one PIC.

In short: it is all digital.

On a sunny day (Thu, 11 Apr 2013 22:31:15 -0500) it happened Vladimir Vassilevsky wrote in :

Only if your code makes it do that ;-)

Digikey has STM6519 for $0.97 for one unit, .675 for 100 10f204 for $0.65 for one unit, .38 for 100

How many do you need for your products ?

The CD4060 is a low cost IC to do long-delay stuff with. Or the 74HC4060 version if you are dealing with lower supply voltages. Essentially it contains an oscillator running at some reasonable clock and a long divider, saving you from having to deal with leakage in electrolytic timing caps.

The CD-series is especially nice because of its wide operating voltage range which makes it easy to run them on an unregulated battery voltage. The more fancy chips are often process-limited to 6V or so.

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Every other programmable component on the assembly is PITA for manufacturing. As it has to be programmed (loaded with software) and tested. And then there is always a question if this revision of MCU software is compatible with PCB revision X and FPGA revision Y, etc, etc.

Vladimir Vassilevsky DSP and Mixed Signal Designs

Seems to me this kind of functionality only makes sense in the context of micro-controller-based gadgets. Its implementation comes down to a few lines of code.

In a well-designed gadget, who needs a reset, anyway?

Jeroen Belleman

On a sunny day (Fri, 12 Apr 2013 10:26:45 -0500) it happened Vladimir Vassilevsky wrote in :

Come on, if you have a FPGA on board use a counter in that.

Uhm, no.

Take a screwdriver and poke with it around a microcontroller. After some time of poking, the micro will hang up till powerdown. It is no matter how good is your code and how good is schematics and layout; despite of all watchdogs and supervisors.

Vladimir Vassilevsky DSP and Mixed Signal Designs

That's software solution; not real hardware reset.

VLV

On a sunny day (Fri, 12 Apr 2013 10:36:55 -0500) it happened Vladimir Vassilevsky wrote in :

Do the same with your eye and it will stop working too. What is your point?

On a sunny day (Fri, 12 Apr 2013 10:43:58 -0500) it happened Vladimir Vassilevsky wrote in :

What does HDL mean to you????

Sure, but not if the circuitry works with regular logic instead of a uC.

The user does, after he finds out it's not so well designed as the designer thought it was :-)

It still rings in my ears. Major luxury CAD vendor, expensive CAD suite. Did not have a reset, you had to do CTRL-ALT-DEL when it crashed. So I called it in because I couldn't work like that. "No this can't be, can we do an online session where you give us control of your desktop" ... "Sure" ... another support engineer walk into room ... then the manager walks in as well ... at some point one of the guys exclaims "I can't believe this is happening!"

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Regards, Joerg 

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My point: Hardware reset must be true hardware reset. It should work no matter what.

Vladimir Vassilevsky DSP and Mixed Signal Designs

That it can hang.

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On a sunny day (Fri, 12 Apr 2013 08:59:47 -0700) it happened Joerg wrote in :

HDL stands for Hardware Description Language. It specifies some hardware configuration. In FPGA how all gates and flipflops, registers and other stuff is connected together. Once configured it is just like the little peeseebees you make, but internal to the chip. Pure hardware.

Sure you can make it go wrong by poking a screwdriver on some FPGA pins, and I am sure I can make your peeseebee designs go wrong by sticking a screwdriver in the right (or wrong depending on POV) places. You are more likely to kill you CD40XXx counter (needs a crystal too!) by poking then to somehow hit and affect an internal counter in FPGA. Even more chances to short some supply rail. Have you even ever programmed a FPGA or written some HDL? Or Vladimir? Silly answers.