Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [clock-speed]

Anything related to clock signal frequency (a.k.a. clock speed) issues in digital systems.

Anything related to clock signal frequency (a.k.a. clock speed) issues in digital systems.

The vast majority of digital systems operate in synchronous mode, i.e. they perform their operations only when they are directed to do so by a synchronization signal, commonly called clock signal or simply clock.

The clock is typically a square wave with a fixed frequency (clock frequency), often with a low duty-cycle. Most digital circuits react to the arrival of either the positive-going or the negative-going edge of clock pulses.

222 questions
37
votes
3 answers

Why do Arduinos ship w/ 16MHz crystal instead of 20MHz?

Why do Arduino boards ship w/ 16MHz crystal instead of 20MHz? They are spec'ed for operating at 20MHz, after all. I guess there are a few advantages to running more slowly (lower power consumption, longer life), but I must be missing something.
JellicleCat
  • 649
  • 1
  • 8
  • 18
27
votes
10 answers

How can you achieve decent clock accuracy in microcontrollers (e.g., max 1 second drift in a year)? How do digital watch manufacturers accomplish it?

I am learning with microcontrollers (mostly PIC16/18 and AVR) for some time, making various experimental projects. One of things that I found surprisingly challenging is maintaining decent clock accuracy. Most of my projects have internal clocks at…
Petr
  • 487
  • 5
  • 11
26
votes
3 answers

How is 255 Tbit/s processed in optical fiber communication?

I have never understood how the new record breaking data transfer speeds are achieved in terms of converting from/to electrical and optical signals. Suppose we have 255 Tbits of data and we want to transfer it in one second. (This is a real world…
stevie
  • 469
  • 5
  • 10
22
votes
5 answers

How to communicate faster than the system clock

I was reading about the new (ish) Thunderbolt 3 today, and was very impressed by the specced speed of 40Gbps. Then I looked at Intel's latest i9 processor speed... about 4.2GHz max. How can a system communicate almost 10 times faster than the clock…
Isaac Middlemiss
  • 670
  • 6
  • 20
20
votes
7 answers

How do I set the clock speed fuses on an ATtiny85 when using an Arduino as a programmer?

I'm following this tutorial, programming the ATtiny85 with an Arduino, using it to play some tones (through a piezo speaker). I'm struggling with getting the tones at the right pitch (I'm creating the wave forms manually, as the tone() function is…
fearoffours
  • 548
  • 2
  • 7
  • 13
19
votes
2 answers

How can a CPU dynamically change its clock frequency?

My Intel CPU changes clock speed depending on the usage, but how does it decide what clock speed to run at? Is the clock speed determined by the OS software using an algorithm, or is it hardware based? Is it dependent on the # of interrupts? The…
Chloe
  • 341
  • 1
  • 2
  • 7
17
votes
2 answers

What generates the clock signal in a fast CPU and how does it work?

Often, for integrated circuits, a quartz crystal is used to generate the clock signal. However, this only reaches speeds in MHz. What component, or what circuit, generates signals up to 5 GHz like in computer processors? How is it possible to…
Markinson
  • 317
  • 1
  • 4
  • 8
12
votes
2 answers

Maximum clock frequency of microprocessors

Recently, I have heard that AMD has released the new Vishera series of FX processors which run at 5 GHZ. My question is whether there is any upper bound of clock rate of a processor? That is can we keep increaing the clock rate for ever? What…
Torsten Hĕrculĕ Cärlemän
  • 257
  • 2
  • 9
12
votes
5 answers

"Overclocking" an AVR

In AVR datasheets under the Electrical Characteristics section you will typically find a graph like this (this one is from the ATMega328): I've seen designs that seem to "work" but operate outside the shaded envelope. Specifically, I've seen 3.3V…
vicatcu
  • 22,499
  • 13
  • 79
  • 155
11
votes
1 answer

HSI and MSI - Applications of two Internal RC OSC in Microcontroller

In a ST microcontroller I'm using there are two OSC's that can be routed to exactly the same hardware and I'm wondering when you would use each one. Link to part documentation STM32L496ZG Excerpt from the data sheet about the two OSC's - -16 MHz…
Hayden James Dekker
  • 138
  • 1
  • 1
  • 7
10
votes
2 answers

AVR interrupt service routine not executing as fast as expected (instruction overhead?)

I'm developing a small logic analyzer with 7 inputs. My target device is an ATmega168 with a 20MHz clock rate. To detect logic changes I use pin change interrupts. Now I'm trying to find out the lowest sample rate I can detected these pin changes. I…
arminb
  • 1,622
  • 4
  • 21
  • 34
10
votes
4 answers

How does the current processor technology with low clock rates (<10 GHz) deals with mmWave (>10 GHz) technology used in 5G?

What I mean is that most abundant computing processors in market have the clock frequencies in the range of 2-4 GHz and from wikipedia: As of 2012, the CPU-Z record for the highest CPU clock rate is 8.79433 GHz on an AMD FX-8350 Piledriver-based…
lousycoder
  • 455
  • 3
  • 11
10
votes
3 answers

How do I calculate needed pixel clock frequency?

If I want to have a resolution of X * Y pixels, updating in frequency f. How do I calculate the pixel clock speed? Example: 1280 x 1024 @ 85Hz usually have a pixel clock of 157.5 MHz, but how do I calculate the needed pixel clock? Need to know to…
Max Kielland
  • 647
  • 2
  • 11
  • 24
9
votes
1 answer

Is a 10GHz clock required to drive a 10Gb serial pin?

I am reading about the 10Gb/s Ethernet PHY for Altera FPGAs (datasheet here). I was impressed to know that, at the hardware level, the 10Gb/s is done serially. Naively, I would think to do 10Gb/s serially, one needs a 10GHz clock. However, 10GHz…
Randomblue
  • 10,953
  • 29
  • 105
  • 178
9
votes
3 answers

Can faster processors/clocks execute more code?

I am writing a program to run on an ATmega 328 which runs at 16Mhz (its an Arduino Duemilanove if you know them, it's an AVR chip). I have an interrupt process running every 100 microseconds. It's impossible, I would say, to work out how much…
jwbensley
  • 581
  • 3
  • 9
  • 22
1
2 3
…
14 15