A digital signal that goes high and low at a specific frequency.
1
vote
4answers
94 views
What is important in computer clocks' signal: signal edges or intervals when signal is stable? Will multiple value propagation occur?
I am trying to figure out some basics of digital electronics. We have all seen the squared graph of the computer clock signal:
I have read multiple articles on the Internet and still can't figure ...
0
votes
0answers
49 views
Clocking scheme for LAN8720A - Cortex M4
This is regarding a design choice involving LAN8720, specific to clocking schemes.
We are interfacing an ARM cortex M4 (with inbuilt MAC) to the 8720 PHY via RMII in the REFCLKO configuration. In the ...
3
votes
3answers
93 views
Why does CPLD has four clock sources?
Altera CPLD EPM570 series have four global clocks(GCLK0-GCLK3)，I want to assign two clock sources to CPLD: one from oscillator and one from a MCU. From "GLOBAL SIGNAL" part of "MAX II Architecture"MAX ...
2
votes
1answer
71 views
How do I buffer a high Frequency clock on a Spartan 6?
I am trying to create a high speed clock on my Spartan 6 Atlys Board. The onboard clonck is 100MHz. I am trying to use an on chip PLL to get a faster clock. I am using a the clocking wizard IP to ...
1
vote
1answer
56 views
Adjustable clock in HDL
I need to generate an adjustable clock in hdl (verilog) on altera cyclone II fpga using signal probes (blocks that can change their output value through jtag - there is no need to recompile the code). ...
1
vote
2answers
89 views
Pipeline question
I'm having trouble with this question.
Assume a 5-stage pipeline and a 200 picosecond clock time.
what is the time required to execute one instruction?
assuming the pipe is kept full, ...
0
votes
1answer
72 views
How can a simple operation such as moving data from one register to another can be encoded into an instruction and executed in a single clock cycle.? [closed]
The simple point I'm trying to make for an essay Im writing. I'm completely at a loss as to how to answer this. Any help available? Sorry, I know this is not a well formed question but I've got no ...
1
vote
0answers
58 views
8284 Clock Generator
I am studying the 8284 clock generator and see how it works with the 8086.
But before I connect the two chips together, I want to verify the 8284 first.
So I placed the 8284 on the breadboard as ...
5
votes
4answers
272 views
Why edge triggering is preferred over level triggering?
I am trying to understand why edge triggering is preferred over level triggering. In my book it is not explained clearly. After searching online I came to know that edge triggering is in-sensitive to ...
2
votes
2answers
208 views
Can I generate 56kHz signal with MCU running at 1Mhz
I am new to embedded systems designing. I have to generate a 56kHz signal with a MCU running at 1Mhz. I want high accuracy. If I just use a timer, it gives me 55.55kHz.
Is there any way I can divide ...
1
vote
1answer
56 views
DS1077 to drive a PIC's clock
I found the DS1077, a "dual-output, programmable, fixed-frequency oscillator". I was wondering if it would be possible to let this chip provide the clock signal for the PIC(18F46K22) that operates the ...
0
votes
0answers
44 views
Measuring CC2420 clock
I'd like to measure the CC2420 clock on a TelosB module that includes a MSP430F1611 microcontroller running the Contiki OS. I turned the CCA pin into a test pin to output the radio's 8 MHz clock. The ...
-5
votes
1answer
95 views
How to multiplex leds using a microcontroller? [closed]
I saw this project online for a simple binary clock:
It's a very simple circuit. What I can't figure out, is how you can control each row separately.
The parts list is as follows:
1 - High ...
1
vote
2answers
107 views
What makes these simple circuit diagrams different?
I'm kind of confused with the behavior changes of these 3 differences of a flip flop.
I made an image to easily show what I'm asking about. I circled the differences in red.. Heres the image:
For ...
0
votes
1answer
191 views
Can someone help check my solution for this timing diagram?
I've been working on some timing diagrams and I keep mixing up the behaviors for the different flip flops.
EDIT:
I think I have the logic correct. If someone could please let me know if I'm ...
2
votes
1answer
90 views
Why does my D Flip Flop Circuit have an X output?
I'm working on one of my projects and I'm having trouble with my flip flops. The project is to design the circuit for a gas pump that has a handle and a sensor. When the handle is down, the pump ...
1
vote
1answer
130 views
What IC should I use to make a binary clock?
I am wanting to make a binary clock. A lot of the schematics I've found are for Arduinos or Raspberry Pi. As much as I appreciate the use of minicontrollers, I don't want to do that for this ...
0
votes
2answers
181 views
Given a gated SR latch, How do I make it a set dominant gated SR latch?
Another weirdly worded question in my digital logic book. It doesn't specifically define set-dominant or reset-dominant - nor does it show how to use these in practice with drawing circuit diagrams. ...
4
votes
4answers
325 views
Why aren't 1Hz crystals used to measure seconds?
According to Wikipedia:
Many clocks use a 32.768KHz crystal. Is this because the crystal is smaller than a 1Hz crystal?
If 1.0 Hz == 1.0 second. Then, why the need for the division?
2
votes
4answers
86 views
What kind of oscillator should I use for a binary clock?
I've seen that a lot of clocks use a 32.768KHz crystal. I'm curious why that is exactly. I am working on a binary clock project with some 4520 ICs. I have some 555 timers too, but I want to use a ...
6
votes
3answers
277 views
Crystal circuit works in breadboard but not in perfboard
I'm a beginner and I'm trying to build a digital clock. My clock generator looks like this:
It works perfectly on the breadboard, where I can see the LED blinking at 2 Hz. However, when I try to ...
2
votes
1answer
65 views
Can I dynamically change the input clock frequency of the AT91SAM3X8E?
Background:
I'm attempting to use an AT91SAM3X8E microcontroller (for Arduino Due compatibility) to create a USB to \$I^{2}S\$ interface. Most \$I^{2}S\$ CODECs require a master clock that is ...
3
votes
1answer
236 views
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 ...
1
vote
1answer
85 views
Choosing Resonator for AtMega328P design
The ATMega328P datasheet specifies a load capacitance for a resonator from 12-22pF but the only 2 Resonators that will fit in my design (from Digikey) have 10pF and 33pF internal capacitors. Which one ...
1
vote
4answers
119 views
9-Bit State Machine
I am working on a state machine that will drive a state bus for a personal project. The state machine will have an output pattern like the following:
...
5
votes
5answers
159 views
How to determinate a reasonable clock frequency for a MCU?
Currently my datalogger is running at 12Mhz, and sleeps 90% of the time. When it's active its mostly blocked by I/O like SD-card or UART.
I suspect the system would still work at 6 Mhz, but how do ...
11
votes
2answers
591 views
How fast is 1 MHz?
How fast is 1 MHz in an AVR microcontroller? Is it actually 1,000,000 Hz or is it 1,048,576 Hz (1,024 Hz * 1,024)?
3
votes
2answers
89 views
Digital Clock --->Bad Accuracy (Help to Troubleshooting)
INTRODUCTION:
I'm a student in the Electronic Engineering program at my University. I'm building a digital clock as a self initiative to learn more. Some of the requirements and steps that is ...
19
votes
6answers
686 views
How precise is the frequency of the AC electricity network?
If I make a digital clock which first detects the AC frequency roughly (whether it is 50, 60, 100Hz, etc), then uses it as its clock pulse source, how precise would it be? Would it work world wide ...
-3
votes
1answer
77 views
LED-colour for clock [closed]
I'm making a big led-clock, and I'll use 55 LEDs per each Segment.
The clock will be 15cm high and consits of 4 Segments. That are approx. 250LEDs.
Now I'm looking for cheap LEDs which suit my ...
0
votes
1answer
140 views
What does the “Q” in “Clock-to-Q delay” stand for? [duplicate]
Possible Duplicate:
Why is the output of stateful elements often named Q?
A register has D (data) as input and Q as output.
What does the Q stand for? I'm having a hard time searching for ...
3
votes
2answers
173 views
Square wave generator has nigh-useless output
I have a system that was designed for testing digital components. I have a device in the system which is used for generation and acquisition of digital signals. Now, I will happily admit to not ...
2
votes
2answers
68 views
clock operating switch
I have 2 channels that I want to switch between every 15 sec.
so I guess I need a switch that switches channels by logical pulse ( lm555 I guess?)
which ic/ circuit would be the best?
Accuracy of the ...
4
votes
1answer
93 views
Clock conversion from 3.3v CMOS to 2.5v
I need to convert a bunch of data signals from an FPGA coming out at 3.3V CMOS into 2.5V for an LCD display. I've found the SN74CB3T16210 and the SN74AVCBH164245 and they both seem like they'll do the ...
1
vote
3answers
358 views
Two wire vs. three wire serial interface for RTC
I'm looking to choose an RTC for a project I have in mind.
I have the following options (linked to datasheet):
DS1307
DS1302
The main difference seems to be the communication protocol. The DS1307 ...
3
votes
4answers
165 views
Understanding Clock Input Signal
I am writing a program to control a dot matrix LCD and display some text on it via PC serial port interface. The LCD have a Pin to Input Clock Signals. I have searched a lot on internet about clock ...
1
vote
2answers
120 views
PIC: What clock is used to program the PIC?
I have a PIC16 that is not connected to an external clock. If I program the PIC with the FLAG setting the clock to an external clock, then will I ever be able to reprogram the PIC?
Is the programming ...
0
votes
2answers
164 views
calculating FSM's maximum clock frequency
Let's assume we have the Truth Table for our Finite state machine.
How can we determine the maximum clock frequency for the system, under the assumptions that the wire delay is 0.3 ns , flip-flop ...
0
votes
1answer
229 views
PIC32mx UART scrambled text
I'm trying to communicate with a PIC32MX795F512H using UART but I get scrambled signs in my terminal.
I know it's a timing/clock issue but I have no idea where and how to fix it.
I am not using an ...
1
vote
2answers
270 views
Flip Flops and Propagation Delay
I'm working on designing an 8 bit home brewed CPU and in this process I'm using Octal D Flip Flops as registers to store data. One of the issues that I've ran into is the need to execute multiple ...
1
vote
1answer
183 views
Timers and internal clock generator on Freescale MCU
I am using MC9S08AW60A with DEMO9S08AW60E Board (Freescale). I have studied about the timers given with the MCU. I wish to know how exactly to Implement timers by code. The Freescale suite also comes ...
2
votes
3answers
313 views
Understanding Flip Flops/Registers in Low Level
So I'm reading "Elements of Computing Systems" trying to really understand how everything works underneath (Any other book/article suggestions that would help would be amazing) Since eventually I want ...
5
votes
3answers
269 views
Is there a preferred placement of termination resistor for a differential clock line?
Looking at a reference design board from Xilinx, we noticed the placement of the termination resistor for a differential clock line (~300 MHz):
The resistor is placed not at the closest possible ...
7
votes
3answers
266 views
Routing 30MHz clock thru several boards
I'm using TLC5945 LED driver. Microcontroller (I'm using LPC1343) must provide a clock for it's internal PWM timer/counter. Maximum allowed clock speed is specified as 30MHz.
I will have several ...
1
vote
1answer
60 views
Datasheet: What is a unit interval (UI) for a PMA?
This datasheet has a table (see Table 3-2) detailing latencies for the two parts of a 10GB Ethernet PHY, namely the PCS (Physical Coding Sublayer) and PMA (Physical Medium Attachment Sublayer).
While ...
6
votes
2answers
1k views
Need help understanding AVR ATMEGA / ATTINY timer mirrored output
I am trying to use Timer1 of Atmel AVR microcontroller, either AtMega328 as used in the Arduino, or the ATTiny85, to output two clock signals which are mirror images of each other. The frequency I am ...
3
votes
1answer
177 views
Clock skew? Good or bad?
So, I've been reading up on clock skew. I came across the fact that clock skew can be incredibly useful, in the sense that positive skew can be used to speed up the circuit by increasing the clock's ...
1
vote
3answers
200 views
How to reduce the clock jitter for an ADC?
I am building a SDR (Software defined radio) and I am trying to clock my 16 bit 130 MS/s ADC. At this speed, the jitter of the clock is very important and a bad jitter can reduce the SNR of my ADC a ...
2
votes
1answer
111 views
FPGA buffered and unbuffered clocks
What are the differences between buffered/unbuffered clocks in a Virtex-6 FPGA?
0
votes
1answer
75 views
Highly accurate CMOS Squave wave clock signal to drive MF5CN Audio filter
The task is to generate a CMOS (+-5[V]) square wave signal with 50% duty cycle in order to drive a second order active filter IC (MF5CN) with variable or fixed frequencies of 150[Khz], 300[kHz], ...
