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19

32kHz ultra low power oscillator: Used for RTCs (Real-time-clock). These can run in the background and enable time-keeping, even when the controller core is sleeping. This enables to have a running clock without the high power consumption of the controller core. The 32kHz oscillators are pretty precise and typically have an error of less than a minute per ...


10

What these are for: 32kHz low power: "digital watch" crystal. Use this when you want to power down the main oscillator but not lose track of what time it is so you can wake up periodically. 32kHz RC: cheaper (no crystal), but less accurate. When you want a digital watch that doesn't tell the correct time. external fast crystal: for things like ...


8

They are not strictly necessary but the vendor is attempting to cover as many use-cases with one part as they can. Some applications may want to use the internal oscillator, others may need a precise clock source, others may want low power consumption. Generally you will use only one in a specific design although in some cases the clock mode is changed ...


6

Here is the clock configuration in block-diagram form from ST's configuration tool (STM32F103). As you can see, there are internal oscillators and two oscillators that use external frequency-determining components (crystals or resonators typically). I have this configured to use an external 8MHz crystal and a 32.768 kHz watch crystal. I could have used the ...


3

The ATSAM family controllers typically have one really slow 32kHz oscillator used for low power applications, either with internal RC oscillator or external quartz crystal. And one high speed internal RC oscillator for "fast as it goes". In addition you can tweak around with PLL's, clock dividers and so on, and of course also provide external ...


3

I have assumed that you just want a high pulse out during the high phase of the clock every 64th clock pulse. 4024 is a negative edge triggered 7 stage binary counter. 4068 is an 8 input Nand gate. 4013 is a Dual D-Type flip flop. Output of nand gate is usually high holding D type flipflop in reset. On a certain falling edge of the clock, the counter will ...


2

Ripple counter, and a one-shot trigger type thing if you want to shorten the extracted pulse.


1

I know it's a little late, but I have been pondering the same thing, and searching the internet for ideas. Although what I was really looking for was validation of my own idea. I have a cheap alarm clock that I bought for exactly this purpose. It operates from a 1.5V AA cell, and has a Lavet mechanism internally. My idea is to set the alarm to 12:00 and ...


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