25
votes
Why is the MCU clock out waveform sinusoidal and not square pulse
It's hard to see (or even generate) a 170 MHz ideal square wave.
Use the 10:1 attenuation mode.
In the 24 MHz case, you probably don't have a good ground connection on your scope probe -- you need a ...
- 13.9k
5
votes
Accepted
Effective way to generate low frequency square wave
One problem with RC oscillators, that concerns you here, is drift with age. It may be possible to find components that will drift slowly enough to stay within 1% of their rated value for a few years, ...
- 8,318
4
votes
Accepted
Is there any MPU where the watchdog has its own clock?
It is reality. This feature is often implemented in microcontrollers. Just as an example, the atMega328 has a separate 128 kHz low frequency oscillator for the hardware watchdog. The datasheet says:
...
- 1,954
3
votes
Effective way to generate low frequency square wave
Depending on what you consider "complex", one cheap way would be to use CD4000 family to build a 32.768kHz quartz oscillator followed by a 5/4096 divider.
One way is to use five (5) DIP ...
3
votes
Why does this capacitor make the measured voltage higher than supplied?
Does anyone have an explanation?
Yes, this is what will happen when a squarewave input is processed by an RC differentiator: -
The output vertical edges are constrained to an amplitude of 3.3 volts ...
- 384k
3
votes
1/60 Hz Counter/Divider
You want to divide by 60. There are several options that would work for the 74HC4059 but the simplest is mode = 2 (Ka, Kb, Kc all high), and a preset of 0030+0 (J5, J6 high, all others low). ...
- 4,705
2
votes
Effective way to generate low frequency square wave
The cheapest is any RC oscillator (the 555 is probably the worst solution for this though) that you manually tune with a potentiometer. Cost should be far below 1€. Temperature stability will be on ...
- 11k
2
votes
Accepted
Some questions about crystal oscillators of an STM32 microcontroller board
The answer is in the manual on p.24.
Excerpt from the respective page:
There are two possible default configurations of the HSE pins, depending on the version of the STM32 Nucleo board hardware.
The ...
- 17.5k
1
vote
Is there any MPU where the watchdog has its own clock?
From the discussion in the comments there also exists "clock watchdog" implementations in some IC's, take for example Microchips "Failsafe Clock monitor":
Source from their ...
- 837
1
vote
Effective way to generate low frequency square wave
You don't need a crazy chain of logic IC if you use a good combination of very few ICs.
It may be done using only a 74HC4060 as proposed by Jens and a 74HC390 and a crystal. Only two logic ICs, not ...
- 2,245
1
vote
Effective way to generate low frequency square wave
If the solution must not involve software, I would probably combine these 3 chips:
74HC4060 is a binary counter with crystal oscillator. Let it run with cheap 4.096 MHz crystal. Use the div 512 ...
- 1,954
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