Why 32768 hz clock

RE: Why Indeed, this is my understanding. I believe a lot of RTC chips rely on that exact division to stop errors creeping in. As to the speed. Generally, it is taken that the faster something oscillates, the more accurate it is.

New Member. It's mostly because Economies of scale dictate that they will always be cheap - a few pence in most cases. So finally, it boils down to what is cheaper and practical to use. And because we had been using Otherwise, given an option, I would have liked to use a XTAL with lower frequency so that accumulated error becomes smaller. It doesn't quite work like that. The lower the frequency, the more difficult it is to get crystals and the frequency tolerance is poor.

And, you can get a precise 1 second period 1 Hz frequency by using a 15 stage binary counter. Practically, in majority of the applications, particularly digital, the current consumption has to be as low as possible to preserve battery life.

So, this frequency is selected as a best compromise between low frequency and convenient manufacture with market availability and real estate in term of physical dimensions while designing board, where low frequency generally means the quartz is physically bigger.

The number is a power of 2, i. If you have a Having a 1Hz frequency means you have a clock signal which provides 1s time resolution: count the seconds with a counter, do the math and you have a Real-Time Clock RTC.

It's primarily due to cost. For a watch crystal, you want to be able to use simple clock dividers and get to a 1s timebase. So a 15 stage binary counter will cycle at 1 Hz. A 16 bit unsigned binary number can represent 0 through Thus :.

I would be VERY surprised if anyone was foolish enough to put a 16 bit processor in a watch. I would expect them to be 4 bit if they are even true micros but would expect that more likely they are dedicated ASICs where each point in the data path is no wider than it absolutely has to be.

There is LOTs of time to process data and if you can save the silicon that an inverter, let along a register, requires you add millions to the bottom line of the profit sheet over time.

I will certainly second this endorsement. Fast reading and filled with a lot of surround that ties so much together - James Cook, the Bounty, pirates, a bunch of cloak-and-dagger, political intrigue, international tensions, personal and professional rivalry and sculduggery. A really fascinating read. Where did you receive your education in Digital electronics or Horology for that matter?

Read Knuth. I don't speak for DSC. But is IS the meaning explicitly defined by the person I was responding to. Not even swiss army watches use, let alone need, a 16 bit processor. In fact most watches do not contain any processor at all. Since there is no processor mostly , this description is far to complicated. A toggle flip flop is one of the most basic digital circuits; it changes its output on every input clock pulse, thus dividing the input frequency by 2.

Obviously, there is no need for a processor so far. With more sophisticated chips, it would of course be possible to use any crystal; but the manufacturers seem to prefer crystal frequencies that are powers of 2, for sake of simplicity. But lower frequency crystals normally lead to less power consumption in digital circuits; that makes Hz crystals the most common ones in battery powered clocks.

Regards Michael. Cut one up and look! Yep, I have an old WW2 Blighley crystal made like this. My opinion on this subject is probably not going to account for much, but I too, have heard of and seen tuning fork shaped crystals. As far as education goes your grammer seems to put you in the latter class. Besides some crystals used in x-tal's are shaped like tuning forks. Let us please remain on topic. I have snipped the original tuning fork reference, and I will follow my interpretation of what the author meant.

He didn't mean that the quartz was cut in the shape of a tuning fork. The parentheses indicate that his meaning was quartz is cut and shaped to resonate a particular way, not in the same SHAPE as a tuning fork, but to achieve a similar result. Am I wrong? William L. Does it fit in a byte?

A quick note, I'm sure you know this, but forgot to mention this: Why not just use a 1Hz crystal? Because of limitations of practical crystals, lower frequencies are generally not found. The reason for the even power of two frequency is simply because it is much easier to make a divide by two frequency divider circuit than a divide by three or five, or some other prime. Since you brought that up I have a question.

I have a circuit I've been wanting to build for some time that calls out a kc x-tal. Anybody know where to find a quantity of one of this seemingly non-existant device.

I've searched for 3 years to no avail except going to a x-tal house and having one custom made. There is no scarcity or loss connected to it. Nothing cost anything. I don't know what you are getting at - especially in the context of this discussion. What are you trying to say when you say, " is multiple of 8 1byte "? Yes, is a multiple of 8, but so is 16 and so is And what is the 1 byte is the above statement supposed to indicate?

It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. Why do we use What will happen if I use a 35 or 25 kHz crystal? Is it that true? The frequency of a real time clock varies with the application. The frequency Hz And, you can get a precise 1 second period 1 Hz frequency by using a 15 stage binary counter.

Practically, in majority of the applications, particularly digital, the current consumption has to be as low as possible to preserve battery life.

So, this frequency is selected as a best compromise between low frequency and convenient manufacture with market availability and real estate in term of physical dimensions while designing board, where low frequency generally means the quartz is physically bigger. The number is a power of 2, i. If you have a Having a 1Hz frequency means you have a clock signal which provides 1s time resolution: count the seconds with a counter, do the math and you have a Real-Time Clock RTC.

It's primarily due to cost. These particular crystals are dirt cheap due to the watch industry. This answer provides more detail, here's an excerpt:. There are 1.