Messaging is a nice concept of displaying useful information during simulation. These
messages can be used to convey wide range of severity levels.
Considerations for implementing messaging
------------------------------------------------
Identify the level of message in terms of severity
Controllability of the message
Timestamp of the message
Message Identification
Different kind of severity levels
------------------------------------------
INFO: Message is simply an information
WARNING: Something unusual happen but no need to stop simulation
ERROR: Indicates that something is wrong and you need to debug and find out
the root cause and fix it
FATAL: Displayed when there is a serious issue. Simulation will immediately
terminate after displaying this message
What is BFM?
-------------------
Provides visibility into its communication processes at each level of abstraction
Visibility into all configurable parameters
Commanded to perform specified sequence of commands
Consideration for designing BFM
-------------------------------------------
Map the hierarchy of protocol or functionality into BFM
Provide a built-in self check capability
Specify all the key variables in one single file
Ensure all configurable variables must have defaults
Must provide a provision to filter the messages
All the inputs to the tasks/commands within the BFM should be checked for legal
ranges.
Must provide a provision for message ID
Typical flow for designing BFM
------------------------------
Specify the abstraction level at which the BFM is planned to be used
Specify user level configuration parameters
Specify the hierarchy of commands when they are functionally dependent on
hierarchical fashion
Specify the commands that user will be able to call within the BFM
Specify the details of the message that BFM should convey
Specify the interface ports that the BFM use to interact with the DFT
Make sure to display the value of parameters before the simulation starts
Provide a provision to log the BFM messages into a file or standard output
Provide a checking mechanism to check the legal range of all the parameters and
input value
Main functions of a bus monitor
=--------------------------------------
Protocol checking
*****************
Violation of protocol
Monitoring for X and Z values on signals
Design latencies between critical signals
Monitor timing violations such as setup and hold
Transaction logging
*******************
Log the message with severity level, ID, and description
Provide the option to display them as standard output or in a file
Thursday, April 1, 2010
Saturday, January 9, 2010
CVS
Computer Vision Syndrome (CVS)
Recent studies have shown that about 85 per cent of computer users suffer from computer vision syndrome
Computer Vision Syndrome (CVS) is a complex eye and vision-related problem associated with computer use. Recent studies have shown that about 85 per cent of computer users suffer from this problem, possibly making it the silent epidemic of the 21st century.
Hence it is important to know a few essential things about CVS.
Symptoms
The primary symptoms are eyestrain, blurred vision, dry and irritated eyes, tired eyes, and headaches. Neck and backaches can also be related to the way we use our eyes at the computer.
Causes
There are several reasons, but the most important reason is that the blink rate (16 / min) is reduced to about 1/3 the normal rate. This leads to irritation, dryness, excessive tearing, burning, itching and redness.
Contact lens wearers also often experience problems with their contact lenses. In response, reflex tearing sometimes occurs and floods the eyes with tears.
Precautions
Use artificial tears to rewet and lubricate your eyes. Lower the computer screen so that the centre of the screen is four to eight inches below your eyes. If seated in a draft or near an air vent, try to eliminate the flow of air past your eyes.
Low humidity or fumes aggravate a dry eye condition, so fix these if possible. Blink whenever you begin to sense eye discomfort; close eyelids and roll eyes frequently.
While working on computers, use glasses with anti-reflection coating. These are advised for those wearing lens as well. For those with presbyopia (glasses for reading after 40 years), the best solution is a lens that is specifically designed for this purpose.
Because the eyes lead the body, the body will assume whatever position is required to enable your eyes to see comfortably. The most optimum viewing distance is considered to be 20-28 inches.
Care for eyes
Care of a person with CVS often requires an expanded case history, testing of the eyes or vision, or treatment since it involves taking into consideration many aspects.
Perfect computer display
Flat panel (LCD) are better than cathode ray tube (CRT) displays since they do not flicker and the contrast is typically higher. Optimal contrast and visibility are attained with black characters on a white background.
The size of the text should be three times the size of the smallest text you can read. Adjust refresh rate (flicker) as high as possible, preferably 85 hertz or higher. For colour monitors, smaller dot pitches (less than 0.28 mm) are desirable.
Adjust the screen contrast so that the characters are clear. Reflections from your computer screen reduce the contrast and make it difficult to see your work. If possible, remove the offending source of light - turn off the source, draw blinds and :
Know the best lighting
Bright lights or other bright objects in your peripheral vision are uncomfortable and can contribute to eye and musculoskeletal symptoms.
* Try the following measures.
* Turn off the light that is bothering you.
* If window light is causing discomfort, draw blinds.
*
Alter your workstation position so that bright overhead lights or bright windows are not in your field of vision. If a desk lamp is causing discomfort, try turning if off and determine whether you can still adequately see your work.
* Use a shield or partition to block bright lights.
Blurring of vision
Intermittent blurring is caused by an inability of the accommodative mechanism to maintain a steady focus on near objects.
This occurs when, after extended near work, the muscles remain fixed or somewhat locked in the near contracted position, effectively making the eye myopic, taking a few seconds to focus on objects. Sometimes this can last for several hours.
This can even affect driving and can be treated with spectacles and exercises. Eyelids flutter or twitch because the muscle surrounding the eye is fatigued. Take periodic breaks, eliminate glares and consider an eye examination.
There is no way that screen and the keyboard can be optimally located with laptops and notebooks and extended work is not recommended on these.
The author is cornea and refractive surgeon, Narayana Netralaya, Bangalore.
Computer Vision Syndrome (CVS)
Recent studies have shown that about 85 per cent of computer users suffer from computer vision syndrome
Computer Vision Syndrome (CVS) is a complex eye and vision-related problem associated with computer use. Recent studies have shown that about 85 per cent of computer users suffer from this problem, possibly making it the silent epidemic of the 21st century.
Hence it is important to know a few essential things about CVS.
Symptoms
The primary symptoms are eyestrain, blurred vision, dry and irritated eyes, tired eyes, and headaches. Neck and backaches can also be related to the way we use our eyes at the computer.
Causes
There are several reasons, but the most important reason is that the blink rate (16 / min) is reduced to about 1/3 the normal rate. This leads to irritation, dryness, excessive tearing, burning, itching and redness.
Contact lens wearers also often experience problems with their contact lenses. In response, reflex tearing sometimes occurs and floods the eyes with tears.
Precautions
Use artificial tears to rewet and lubricate your eyes. Lower the computer screen so that the centre of the screen is four to eight inches below your eyes. If seated in a draft or near an air vent, try to eliminate the flow of air past your eyes.
Low humidity or fumes aggravate a dry eye condition, so fix these if possible. Blink whenever you begin to sense eye discomfort; close eyelids and roll eyes frequently.
While working on computers, use glasses with anti-reflection coating. These are advised for those wearing lens as well. For those with presbyopia (glasses for reading after 40 years), the best solution is a lens that is specifically designed for this purpose.
Because the eyes lead the body, the body will assume whatever position is required to enable your eyes to see comfortably. The most optimum viewing distance is considered to be 20-28 inches.
Care for eyes
Care of a person with CVS often requires an expanded case history, testing of the eyes or vision, or treatment since it involves taking into consideration many aspects.
Perfect computer display
Flat panel (LCD) are better than cathode ray tube (CRT) displays since they do not flicker and the contrast is typically higher. Optimal contrast and visibility are attained with black characters on a white background.
The size of the text should be three times the size of the smallest text you can read. Adjust refresh rate (flicker) as high as possible, preferably 85 hertz or higher. For colour monitors, smaller dot pitches (less than 0.28 mm) are desirable.
Adjust the screen contrast so that the characters are clear. Reflections from your computer screen reduce the contrast and make it difficult to see your work. If possible, remove the offending source of light - turn off the source, draw blinds and :
Know the best lighting
Bright lights or other bright objects in your peripheral vision are uncomfortable and can contribute to eye and musculoskeletal symptoms.
* Try the following measures.
* Turn off the light that is bothering you.
* If window light is causing discomfort, draw blinds.
*
Alter your workstation position so that bright overhead lights or bright windows are not in your field of vision. If a desk lamp is causing discomfort, try turning if off and determine whether you can still adequately see your work.
* Use a shield or partition to block bright lights.
Blurring of vision
Intermittent blurring is caused by an inability of the accommodative mechanism to maintain a steady focus on near objects.
This occurs when, after extended near work, the muscles remain fixed or somewhat locked in the near contracted position, effectively making the eye myopic, taking a few seconds to focus on objects. Sometimes this can last for several hours.
This can even affect driving and can be treated with spectacles and exercises. Eyelids flutter or twitch because the muscle surrounding the eye is fatigued. Take periodic breaks, eliminate glares and consider an eye examination.
There is no way that screen and the keyboard can be optimally located with laptops and notebooks and extended work is not recommended on these.
The author is cornea and refractive surgeon, Narayana Netralaya, Bangalore.
Computer Vision Syndrome (CVS)
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