More digital circuits
Download
1 / 22

More Digital circuits - PowerPoint PPT Presentation


  • 139 Views
  • Uploaded on

More Digital circuits. Ripple Counter. The most common counter The problem is that, because more than one output is changing at once, the signal is glichy To avoid this problem, use Gray or Johnson code. Johnson Counter. The Johnson counter is type of shift counter

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'More Digital circuits' - spike


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Ripple counter
Ripple Counter

  • The most common counter

  • The problem is that, because more than one output is changing at once, the signal is glichy

  • To avoid this problem, use Gray or Johnson code


Johnson counter
Johnson Counter

  • The Johnson counter is type of shift counter

  • Put an inverted MSB back to LSB

  • Glitch output free



Linear feedback shift registers
Linear Feedback Shift Registers

  • A small number of taps are recycled

  • An LFSR can operate at high speed compared to a binary counter because the feedback logic is very simple

  • Reduce clock noise




Maximal length lfsr
Maximal length LFSR

  • With maximal length logic (taps selected to give the maximal count), a small number of register can create sequence up to 2n-1


Divide by n lfsr counter
Divide by N LFSR Counter

  • An example of the use of a LFSR

  • A terminal count is provided as an input to be compared to



4 bit lfsr one to many code
4-Bit LFSR One-to-Many Code

  • One-to-Many variant splits the XOR into 2-input gates and distributes them throughout the register array


Cyclic redundancy checksums
Cyclic Redundancy Checksums

  • Error detection

  • The data packet is looked at as a huge binary number

  • A polynomial divide this number in GF

  • Reminder is checksum



More digital circuits
ROM

  • ROM stands for Read-Only Memory

  • This memory is initialized when the FPGA is configured and cannot be changed after configuration


Rom version of lfsr
ROM Version of LFSR

  • We can implement four-bit LFSR counter with a ROM


More digital circuits
RAM

  • RAM stands for Random Access Memory

  • A RAM is an array of cells, addressable in groups N element wide and M elements deep



More digital circuits
RAM

  • Unless the FPGA support embedded RAM blocks, it will consume a huge amount of logic





More digital circuits

  • Jovan Popovic jocapc@panet.co.yu

  • Milos Milovanovic miloshm@yahoo.com

  • Veljko Milutinovic vm@galeb.etf.bg.ac.yu

  • Nobelovac?