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Questions tagged [clock-speed]

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

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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 ...
vicatcu's user avatar
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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 ...
Torsten Hĕrculĕ Cärlemän's user avatar
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?...
Chloe's user avatar
  • 341
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. ...
arminb's user avatar
  • 1,622
5 votes
3 answers

How to calculate the time of one single tick on microcontroller

I have been in Embedded system for 8 months. I have worked application part more compare with low level. I have basic questions on systems ticks, How to calculate the system tick of Timer, if I am ...
user2732944's user avatar
19 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 ...
fearoffours's user avatar
8 votes
4 answers

Exotic semiconductors for fast digital ASIC

I am researching exotic semiconductors for a digital ASIC with a few million logic gates which should run as fast as possible within a $30 million budget. (Specifically, I need to do a single fully-...
Randomblue's user avatar
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6 votes
1 answer

Is CPU/GPGPU heat dissipation quadratic in clock frequency?

In the following article on overclocking a Pentium from 1GHz to 5GHz using liquid nitrogen: The 5GHz Project, there is an assertion that "Heat dissipation rises exponentially during extreme ...
user29254's user avatar
4 votes
3 answers

ATmega - Why is the prescaler factory defaulted to 8?

Why do ATmega (e.g. 328P or 644P) have CKDIV8 (or CLKPS = 0011) factory programmed along with a default internal 8 MHz ...
try-catch-finally's user avatar
3 votes
3 answers

Capacitive load - Matching Right Crystal and Caps for oscillator circuit - DS1302 RTC - cut and trim

CL = (C1 * C2) / (C1 + C2) + Cstray I have a 12.5pf crystal. DS1302 is happy with 6pf. what is trim capacitors to make him happy using 12.5pf? 12.5-6=6.5pf (6.5*6.5) / (6.5+6.5) + cstray= 3.25pf + ...
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2 votes
1 answer

How to constrain a source-synchronous FPGA input?

I have a source-synchronous input to my FPGA (an Intel Cyclone 10 GX 10CX085), coming from an external chip whose datasheet gives the following information: fmax = 300 MHz (single data rate) tsetup = ...
Harry's user avatar
  • 230
1 vote
1 answer

Cascade shift registers driven by single-cycle microcontroller

I'm trying to make a unit in which 4 digits can be updated in a small amount of time from a single-cycle microcontroller (preferably all digits updated within 5uS) My circuit is setup in the ...
Mike -- No longer here's user avatar
1 vote
1 answer

Error in dsPIC33 Family Reference Manual Oscillator?

I'm using an external 20MHz (categorized as high-speed or HS range) resonator and using PLL, but I'm not able to clock the device up anywhere near the max cpu speed advertised. How are you ever ...
tarabyte's user avatar
  • 3,092
1 vote
4 answers

Why do we use negative edge trigger Flip Flop instead of positive edge triggered?

The glitches due to race condition can be avoided by using a negative-edge triggered flip-flop instead of the positive-edge-triggered flip-flop used. What does this mean? Source: http://www.zeepedia....
Sai Gautham's user avatar
1 vote
3 answers

Reading data from digital pressure sensor (Pressure sensor SPD100GD)

We need to read the digital output from a Pressure sensor SPD100GD with an AVR micro (Atmega128). According to the datasheet we must estimate transmission speed. The datasheet is saying: The ...
Soheil Paper's user avatar
1 vote
1 answer

DDR2 data rate and data bus confusion

I've been reading about DDR2 memory for the past few days and have got confused with some of the terms involved. I am mainly confused with discrete memory (single DDR2 memory IC) rather than DIMM ...
LoveEnigma's user avatar
0 votes
1 answer

Zedboard clock cycles analysis

Based on the example in here, I tried a very similar example (but instead of multiplying two matrices I just multiply all the elements in a matrix by 2.0). However, when comparing the results of ...
João Pereira's user avatar
0 votes
2 answers

ATmega 32 Clock Frequency Issue

I'm currently using ATmega32 device with external clock speed of 16 MHz . the problem when i use a delay of for example 16,000 ms in the software, it actually delays only a 1000 ms in actual world. I ...
ahm_zahran's user avatar