Questions tagged [clock-speed]

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

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74 views

What is Symbol Clock Frequency?

I came across the term Symbol Clock Frequency in this Intel programmer reference manual (P131). I could not find what the symbol clock frequency actually is in the manual or online and thought it ...
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400 views

Ways to observe clock signal of an STM32 MCU

Is there a nice way to be able to observe the clock signal in an oscilloscope to validate my settings for clock speed? After setting it to 168 MHz with PLL for an STM32F407VGT6 MCU let's say.
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54 views

Find critical path and maximum clock frequency in digital circuit

I have this problem: Consider this circuit: Find and describe the critical path. What is the maximum clock frequency? MY ATTEMPT Okay, this is how I see the critical path: DFF -> G1 ->...
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1answer
59 views

Oscillator slows down when my hand hovers over it

I'm teaching myself VHDL using this MAX II CPLD board. I designed a frequency divider and 4-bit counter in VHDL using the onboard 50MHz oscillator. It seemed to work as the onboard LEDs are flashing ...
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79 views

Calculate C and R in a CMOS Crystal Oscillator

I stumbled over this simple solution to drive a crystal oscillator, but I need to connect a 25.17MHz crystal instead of the 10MHz in this schematic. How do I calculate R1 and C for a given frequency f(...
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1answer
95 views

How to synchronize PIC PWM clocks?

I'm considering a design which has multiple PIC-based controllers producing PWM signals at 31 kHz. Sometimes, under a well-defined "handover" condition, some pair of PWM power feeds will be connected ...
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28 views

How to pick clock speeds for a CS4270 codec?

I'm in the process of designing a circuit which includes a Cirrus CS4270 codec and a STM32F405 running as a DSP. I'm trying to define my max usable settings, which would be running at Fs = 192kHz. I'...
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89 views

WAVGAT Pro Mini, no serial output

I ordered some Pro Minis however get some WAVGAT clone thingies. The first problem was it is running too slow (4x slower) when compiling with default "Pro or Pro Mini" board profile. Serial however ...
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46 views

How to compute clock cycle time from given frequency

let's say I have a processor runs at 100MHZ frequency how can I compute from this it's clock time for each cycle? I know that Frequency = 1 / Clock Time but I am having trouble to fully understand how ...
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110 views

Increasing system clock frequency on STM32F303 drops I2C clock proportionately - why?

I'm trying to figure out a weird little issue I've discovered while debugging another element of my code. I've got a STM32F303K8 reading and writing to an I2C peripheral. The I2C clock speed is ...
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4answers
4k views

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 ...
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113 views

ATTiny85 clock speed problem

Using an ATTiny85 and an Arduino loader I created a simple device for turning on an exhaust fan based on a light sensor. The ATTiny85 turns on the fan after activating a warning light and sounding an ...
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62 views

How to set up clock for the STM32 Nucleo-64 with libopencm3/rtos

I was using this code from github on a blue pill. Now I would like to adapt it for STM32F401 on a Nucleo-64 board. I tried changing the GPIO to A7 and attaching an led (which lit up when I attached it ...
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78 views

How can I create a long (10 second) pulse from a short active pulse?

So let's say I have an incoming signal: 1 clock cycle from a ~1-100 MHz (50 MHz for this example) clock domain. And I want to drive an output that must be active high for 10 seconds for each time the ...
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2answers
48 views

Clock Generation from Oscillator

Is there specific standard ways to generate clocks from oscillators? Referring to generating a square-wave clock from a sinusoidal oscillator output. I can think of a few circuits involving diodes as ...
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1answer
62 views

Sleep vs low frequency

Some processors have a low frequency mode for using in low power mode. For example MSP430 microcontroller can work in both Normal clock frequency 16M Hz Low clock frequency 32 kHz I am wondering if ...
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2answers
122 views

What is the significance of 111 in clock speed?

Never really thought about it until recently, but it looks like the number 111 appears very frequently in clock speeds and such: the first example that comes to my mind is one of the handheld game ...
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1answer
238 views

How to query APB1 clock frequency?

I'm trying to query the current value of the APB1 clock frequency to input into a USART configuration. Ideally, I could just query whatever the USART2 clock source is on an STM32F302xx, in case I ...
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1answer
101 views

Micro controller clock speed requirement for delay measurement

I am trying to measure the absolute time between two 1Hz clocks (GPS PPS events) to within 50 nanoseconds. I do not necessarily care which clock occurs first, I am only looking for the delta T between ...
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1answer
187 views

SPI clock selection

Using STM32l476 controller. Master is running at 30 MHz and slave is running 15 MHz. In SPImaster, clock should be system clock/2. In slave, clock should be system clock/4. Question: My ...
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2answers
758 views

How to use 1PPS to Synchronize ESP32 Clocks and Peripherals

I've read a few posts (example) about what the 1PPS signal is and how it can be used at a high-level, but I'm still not sure how to actually implement it on a PCB schematic to sync up with my ...
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1answer
383 views

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 ...
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4answers
96 views

Could we theoretically massively increase number of parallel computations (for some problems) by getting rid of cpu clocking?

CPU clocking involves making sure that each operation or part of an operation takes exactly a certain amount of time (the machine cycle time). One way to increase the efficiency of a cpu is by ...
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1k views

Relationship between I2C drawn energy / power consumption and data rate

Referring to just what the I2C lines draw, am I wrong thinking that the higher the clock frequency the shorter the time there will be (the same amount of) current flowing through the pullups and thus ...
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1answer
244 views

Asynchronous FIFO in clock domain crossing

Clock domain crossing issue can be solved by using asynchronus FIFO with input frequency f1 is of the source domain and f2 is of the destination frequency. If the data is sent in bursts, depth can be ...
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103 views

Have I bricked my ATMEGA3328p by setting

I was playing around with setting the "system clock prescalar" (CLKPR). I'm now in a situation where I can see that the clock is 244.9KHz, using my logic analyser and the "Clock output on PORTB0" ...
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260 views

What are the advantages of a wider bus in comparison to those of a higher clock frequency? [closed]

The aim is to increase data transfer rate. I understand each may have some drawbacks and advantages. Frankly I'm not knowledgeable enough to know of many so I'd like some input from others. I know ...
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386 views

Slow clock speed with Atmega328P AVR microcontroller on breadboard

I have a small breadboard with an Atmega328p 28 pin microcontroller with a 16 MHz crystal and two 20 pF capacitors on it (similar to this demo: https://www.arduino.cc/en/Tutorial/ArduinoToBreadboard). ...
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2answers
356 views

Overclocking an image sensor for higher FPS

What happens if I overclock an image sensor? For instance the OV7670 (datasheet) which has a rated maximum system clock input (XCLK) of 24 MHz and maximum pixel clock (PCLK) of again 24 MHz. The ...
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2answers
310 views

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 ...
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4answers
656 views

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-...
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1answer
143 views

Quartz Clock Accuracy

Do the vibrations of aircraft engines (or any engine, for that matter) dilute the accuracy of a quartz clock? I haven't done any kind of research or hypothesis testing, though I believe that the ...
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1answer
159 views

LCD SPI clock frequency with STM32L0 MCU

I'm designing a PCB that includes LCD Display NHD-C12832A1Z-FSW-FBW-3V3 (datasheet) connected to the STM32L071KZU6 microcontroller (datasheet). I'm afraid that the SPI interface of the LCD will not ...
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4answers
2k views

Is there a small (6-pin) DIP I can use to generate multi-MHz squarewave clocks with an external crystal?

I'm building a circuit that I'd like to run at 8 MHz to begin with, but I want to be able to try it out at 10, 12, 16, 20, and, maybe, 25 MHz. I know that many microcontrollers have the ability to ...
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5answers
4k views

Why are DIMMs not equipped with a heat sink like a CPU?

I know that a DIMM is composed of a set of chips that contain control logic managing the decode and prefetching memory operations. According to a product specification, I found that newer RAM works at ...
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4answers
399 views

Maximum Clock Frequency

As an assignment for the HDL course I'm taking, I've to design an FIR Filter. The module consists of two a small combinational circuit which can be used to reset the module, another combinational part ...
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2answers
806 views

How to set external clock value for STM32F1?

I creating a project with the microcontroller STM32F101C8t. This microcontroller has an internal clock of 36MHz. My question is how to correctly set the external clock value, ie what crystal value ...
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3answers
3k views

What is the fastest arduino to PC communication method?

I am making an application that has multiple i2c sensors controlled by an Arduino Uno. I want to get all of the raw data from the sensors and transfer them to a PC as fast as possible, on which I will ...
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2answers
404 views

Correct terminology for 'clock' that doesn't oscillate?

What would be the correct term for a clock input that isn't made to oscillate per se? In an attempt to only allow input A to have any effect on a circuit at a chosen time, one could AND it with ...
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231 views

High frequency clock from clocked RS latch

We were taught that this circuit is not of much use as when CLK=1, J=1 & K=1, Q toggles at a very high rate. So suppose I want to make a high-frequency clock, can I use this? Of course, the ...
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2answers
169 views

STM32F0x1 run SYSCLK at 1MHz with 8 MHz external crystal

I am using hardware with an 8 MHz external crystal and would like to reduce the SYSCLK frequency to 1MHz. I haven't been able to do this yet. Is it possible to achieve this with certain PLL and DIV ...
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3answers
429 views

Simplest shift register test circuit - clock

I'm looking for the simplest way to test the operation of a 74HC595 shift register without complex circuitry. Currently (on a breadboard) I have a 47K SIP resistor in a pull-up fashion connected to ...
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2answers
800 views

PLL vs Higher frequency crystal oscillator for fpga [closed]

I need 100MHz clock frequency to implement my HDL design on an FPGA. Is it better to use an FPGA board with 100MHz crystal oscillator or use PLL to increase the frequency? What are the advantages and ...
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0answers
41 views

Faster 8051 not taking the slower 8051 pin status correctly

I'm trying to do a rather simple data transaction between two 8051 microcontrollers using a variant of the SPI protocol. The large one is a slave and the small one is a master. The documentation for ...
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3answers
146 views

What determines the maximum size of a cpu cache?

Looking at a list of the very latest CPUs, I see several of them with a cache size of 12MB or 8MB - pretty small, when compared to the ever-increasing size of hard drives and ram. It seems to be taken ...
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1answer
357 views

Codec in 'master mode' require more than one external clock? (MCLK?) to drive I2S system timing to/from MCU slave?

Does an audio codec in 'master mode' require more than the one clock line (MCLK?) to drive and time I2S data sync to MCU or FPGA slave? I understand that the I2S proper consists of three lines - '...
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2answers
1k views

Why do micro controllers run @ 100's MHz whilst CPUs run @ GHz? [closed]

Whoopie - I've got a Raspberry Pi. When doing stuff it runs @ 1.2GHz and there are Uber overclockers out there who have boosted them to 1.5GHz (with phase change coolers). Today, the cheapest CPU on ...
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1answer
75 views

Is it possible to connect eight digital inputs to a digital output? [closed]

Can eight digital inputs (at 20-Mhz) output to 160-Mhz? Does a multiplexer work for this? Thanks for your answers.
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1k views

Does a baudrate in serial communication (USB or RS232) need to be exact?

In serial communication, does the baudrate mean we have to use the exact clock speed or is it a range of speeds that we can use? and if it's an exact value, how exact should it be ? for example, can ...
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1answer
602 views

How to set ADC clock in low power mode?

I am measuring the voltage with the STM32L011K4 MCU. When the processor goes into low power sleep mode, I start reading the wrong values from an ADC. I think the reason is caused by the system clock ...