Skip to main content
43 votes

How would I go about getting a small oscillator running at precisely 31,891,269,116 µHz?

You can do better than Brian Drummond's suggestion. Although it may be true that your oscillator is the biggest source of error in the system, there's no reason to add additional systematic error when ...
hobbs's user avatar
  • 7,450
40 votes

Why are 555 timers so prevalent?

I'm not a 555 fan and only used them a couple of times over several decades but they do have their uses. Why is the 555 so prevalent, or ubiquitous; what about it so useful? It was probably the ...
Transistor's user avatar
  • 176k
27 votes

How do I make a nanoseconds counter?

You've changed the requirements by a lot! Measuring something in nanoseconds is hard. Measuring something with a +-100 ns accuracy really isn't. A 10 MHz counter works perfectly fine for that, do 20 ...
Marcus Müller's user avatar
22 votes

Why doesn't the switch command in this code work?

I didn't inspect the whole code but you forgot the "break" statement for each "case" : without it your code will perpetually exit the switch statement by executing "case 9&...
Genorme's user avatar
  • 701
17 votes

Why are 555 timers so prevalent?

The IC was designed in 1971 by Hans R. Camenzind under contract to Signetics and introduced in 1972. The 555 is still in widespread use due to its low price, ease of use, and stability. It is now made ...
Trevor_G's user avatar
  • 46.7k
16 votes

How would I go about getting a small oscillator running at precisely 31,891,269,116 µHz?

An Oscillator running at precisely 31,891,269,116 µhz or a timer with 1.0274912510 seconds period would require a precision of at least \$10^{-10}\$. Your best bet is to use an atomic clock which can ...
Dmitry Grigoryev's user avatar
16 votes

How do I make a nanoseconds counter?

Luxury option: Time to digital converter chip, available from several manufacturers. Accuracy: picoseconds. AS6500 TDC7200 Easy option: Microcontroller timer in capture mode to measure pulse width, or ...
bobflux's user avatar
  • 77.6k
15 votes

How would I go about getting a small oscillator running at precisely 31,891,269,116 µHz?

It could be done with a rubidium or other atomic reference clock at 10MHz, perhaps a PLL to give (say) 100MHz, and then counted with a ~36 bit phase accumulator to give 0.001Hz resolution. The latter ...
Spehro Pefhany's user avatar
13 votes

Difference between internal and external oscillator for a microcontroller?

It depends on what you want to use the processor for, the manufacturer, etc. RC internal oscillators are "only" good for 1-2% accuracy, there are some processors that have tuning adjustment registers ...
user201365's user avatar
  • 2,004
12 votes
Accepted

Inaccurate timer interrupt STM32

There are two things wrong with your code: 1) you attempt to reset and restart the counter in the interrupt handler with "TIM1->EGR |= 0x01;" . But you're using the automatic reload mode of the ...
james's user avatar
  • 1,692
11 votes

DMA triggered by Timer using STM32F4-Discovery board

The big reason the DMA isn't transferring is that it isn't actually connected to the peripheral. In most Cortex implementations I've seen, there are multiple memory buses. The ST implementation isn'...
pgvoorhees's user avatar
  • 2,516
10 votes

555 timer with output voltage equal to 5V?

The output voltage will never quite reach the supply voltage. From your datasheet: With a 10mA load to +5 you'll see 100mV or more drop when sinking 10mA, and about 1.45V drop (meaning output ...
Spehro Pefhany's user avatar
10 votes

How do I produce a 1Hz clock output using a 555 timer IC? Are there better ways other than a 555 timer IC?

The actual 555 timer frequency depends on the RC time constant, which is strongly affected by variations in the actual resistance and capacitance. The resistor has initial accuracy spec (like 1% or 0....
MarkU's user avatar
  • 14.7k
9 votes

Why are 555 timers so prevalent?

It depends on what you mean by common. The 555 is very widely used on hobby and home brew projects and in simple example circuits as found on the web. This is because it's flexible, simple to use and ...
Andrew's user avatar
  • 6,902
9 votes
Accepted

STM32 Logic level high and low thresholds

The logic levels are described in section 6.3.14. When your supply voltage is 3.3V then: V_IL = 0.39 * Vcc - 0.06 = 1.23 V (table row "I/O input low level voltage except BOOT0". The maximum voltage ...
filo's user avatar
  • 8,961
9 votes

How do I make a nanoseconds counter?

(basically +/- 100ns). Well then, a cheap 8-bit microncontroller like ATTINY2313 can be clocked at 20Mhz, then you can just use its timers in input capture mode and that will get you +/- 25ns ...
Jasen  Слава Україні's user avatar
8 votes

Difference between internal and external oscillator for a microcontroller?

Main difference is that the internal oscillator is usually a RC type oscillator which is not very accurate. External oscillators can be of type quartz crystal which are far more accurate.
Stefan Wyss's user avatar
  • 7,430
8 votes
Accepted

STM32F3 - diffrence between PWM1 and PWM2

It is documented in the Reference Manual, at the register descriptions. TIMx capture/compare mode register 1 (TIMx_CCMR1) [...] 0110: PWM mode 1 - In upcounting, channel 1 is active as ...
followed Monica to Codidact's user avatar
8 votes

How do I make a nanoseconds counter?

I think the most realistic approach here is probably still a bit tricky: First of all, you'll have to realize that your signal has a pretty high bandwidth, assuming that the rise time of your pulses ...
Marcus Müller's user avatar
7 votes
Accepted

555 timer with output voltage equal to 5V?

For most 555's, the output-high voltage is whatever is provided as the supply voltage. So if you give the 555 9V it will output at 9V, if it give it 5V it will output at 5V. This is with the ...
jbord39's user avatar
  • 4,350
7 votes

How would I go about getting a small oscillator running at precisely 31,891,269,116 µHz?

You don't define "expensive", so this is something of a shot in the dark. Start with a commercially (including eBay) 10 MHz generator. Rubidium for choice, but whatever accuracy you can get sets your ...
WhatRoughBeast's user avatar
7 votes

Timer1 remap cause debug crash on STM32F103

STM32F103 [...] STM32CubeMx [...] when I start the debug session and when the MCU executes the macro "__HAL_AFIO_REMAP_TIM1_ENABLE()" the debug session crash. I don't use the STM32CubeMX HAL, but I ...
SamGibson's user avatar
  • 17.9k
7 votes

Astable 555 circuit not oscillating

As has been mentioned, Pin 4 should be connected to +V and also pin 5 decoupled to ground by about 10nF. The 555 should not get hot at all! This is the big clue. I've played with this circuit and I ...
Peter Jennings's user avatar
7 votes
Accepted

How to automatically turn off a Fan after a fixed amount of time?

Replace the existing switch with a UL-rated timer switch. Anything else will run the risk of invalidating your fire insurance.
Dave Tweed's user avatar
  • 173k
7 votes

What space applications use the 555 timer?

It's used for the same sort of stuff you'd use it for on the ground. As a timer, as an oscillator, for pulse generation, as a watchdog timer... you have many of the same needs aboard a spacecraft as ...
Synchrondyne's user avatar
  • 3,764
7 votes

How to increase STM32 Timer (encoder mode) counter value?

I can see 2 solution : Use a 32 bit timer instead of a 16 bit timer : you haven't specifyed the exact micro-controler you use, but at least for STM32F401xB/STM32F401xC (section 3.19.2), there are 2 ...
Sandro's user avatar
  • 7,277

Only top scored, non community-wiki answers of a minimum length are eligible