On Wednesday, July 5, 2023 at 7:10:27 AM UTC+10, Piotr Wyderski wrote:
> John Woodgate wrote: 
> > I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge.
> Any sub-dollar MCU would run from 2^15Hz input and provide you with a 
> timer to divide by 20. Why bother using these ancient CD4000 parts? 

The project has a tutorial element. People have to understand exactly what's going on, and walking them through the source code doesn't seem to be an acceptable way of providing it.

-- 
Bill Sloman, Sydney

On Wed, 05 Jul 2023 01:50:05 +0300, LM <sala.nimi@mail.com> wrote:

>32kHz crystals are very hard to get oscillating.
>Higher frequency oscillate with any circuit.
>
>On Mon, 03 Jul 2023 19:15:34 -0700, John Larkin
><jlarkin@highlandSNIPMEtechnology.com> wrote:
>
>>On Mon, 3 Jul 2023 21:47:37 +0100, piglet <erichpwagner@hotmail.com>
>>wrote:
>>
>>>On 26/06/2023 15:20, John Woodgate wrote:
>>>> I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator.
>>>> 
>>>> I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is  a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine.
>>>
>>>Back in the mid 1970s I was able to make 4013 oscillate but that was 
>>>with the first generation "A" family. Buffered 4013B parts proved 
>>>impossible to make oscillate.
>>>
>>>Sorry to be late to see this thread.
>>>
>>>piglet
>>
>>Anything with power gain can be made to oscillate, but not always with
>>a simple RC or crystal circuit.

I've seen higher frequency xo circuits that weren't reliable in
production. The circuit and the caps have to match up with the crystal
motional equivalents, and thay can vary a lot. Some purchasing agent
buys a different crystal and it doesn't work.

John Larkin wrote:

> The thing that impresses me about the Pi is how they did everything
> right.

1. There's no 64-bit counter that can be clocked from a 32768Hz clock.
2. The interpolators don't work with DMA.
3. The DMA can't auto-restart (without chaining).
4. Many IRQ sources share an IRQ line, so handler dispatching is annoying.

I use the RP2040 to decompress an FPGA bitstream, decode audio files for 
playback and handle the WS2812B status LED chains, as the chip starts 
first. The Artix does the rest.

     Best regards, Piotr

32kHz crystals are very hard to get oscillating.
Higher frequency oscillate with any circuit.

On Mon, 03 Jul 2023 19:15:34 -0700, John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote:

>On Mon, 3 Jul 2023 21:47:37 +0100, piglet <erichpwagner@hotmail.com>
>wrote:
>
>>On 26/06/2023 15:20, John Woodgate wrote:
>>> I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator.
>>> 
>>> I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is  a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine.
>>
>>Back in the mid 1970s I was able to make 4013 oscillate but that was 
>>with the first generation "A" family. Buffered 4013B parts proved 
>>impossible to make oscillate.
>>
>>Sorry to be late to see this thread.
>>
>>piglet
>
>Anything with power gain can be made to oscillate, but not always with
>a simple RC or crystal circuit.

Phil Hobbs wrote:

> Plus a 74HC1G04 or something for the oscillator.

An off-the-shelf oscillator would work far better. RTC oscillators share 
many traits with memcpy(): only selected few can make both *right*. :-)

	Best regards, Piotr

Lasse Langwadt Christensen wrote:

> and it'll have a dac or pwm to do a decent sinewave, but you have to know how to program it ...

All the program needs to do here is to setup a timer for /20 and connect 
it to a GPIO somehow. With all due respect, if that's considered 
difficult, I'd suggest changing the hobby.

     Best regards, Piotr

tirsdag den 4. juli 2023 kl. 23.10.27 UTC+2 skrev Piotr Wyderski:
> John Woodgate wrote: 
> > I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge.
> Any sub-dollar MCU would run from 2^15Hz input and provide you with a 
> timer to divide by 20. Why bother using these ancient CD4000 parts? 

and it'll have a dac or pwm to do a decent sinewave, but you have to know how to program it ...

John Woodgate wrote:
> I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge.

Any sub-dollar MCU would run from 2^15Hz input and provide you with a 
timer to divide by 20. Why bother using these ancient CD4000 parts?

     Best regards, Piotr

On Mon, 3 Jul 2023 21:47:37 +0100, piglet <erichpwagner@hotmail.com>
wrote:

>On 26/06/2023 15:20, John Woodgate wrote:
>> I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator.
>> 
>> I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is  a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine.
>
>Back in the mid 1970s I was able to make 4013 oscillate but that was 
>with the first generation "A" family. Buffered 4013B parts proved 
>impossible to make oscillate.
>
>Sorry to be late to see this thread.
>
>piglet

Anything with power gain can be made to oscillate, but not always with
a simple RC or crystal circuit.

On Monday, July 3, 2023 at 4:47:46 PM UTC-4, piglet wrote:
> On 26/06/2023 15:20, John Woodgate wrote: 
> > I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator. 
> > 
> > I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine.
> Back in the mid 1970s I was able to make 4013 oscillate but that was 
> with the first generation "A" family. Buffered 4013B parts proved 
> impossible to make oscillate. 
> 
> Sorry to be late to see this thread. 

4013A and 4013B are different parts.  They have the same logic functions, but the A is single buffered and the B is double buffered.  As such, the A has a workable range of input voltage which will produce a linear change in output voltage.  The B series has a much, much more narrow range of input that will do anything other than switch the output rail to rail.   

-- 

  Rick C.

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