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Hello...i am new to VHDL, and learning how to
program using a Cypress CPLD.
Anybody got some simple code to turn on and turn off
an LED???
please email sample code to datalines@excite.com
TIA
--For active high:
LedOut <= '1' ;
For a simple on/off with a switch:
LedOut <= SwitchIn ;
Of course you probably should debounce the switch input
and register the LedOut output. For debounce,
do a search of the newsgroup. Assume that your
switch is bouncing if it has not been stable for
anywhere from 5 ms to 15 ms.
If you bought your board, there may be a test
code that your vendor provides that does this.
Cheers,
Jim
network lines wrote:
Hello...i am new to VHDL, and learning how to
program using a Cypress CPLD.
Anybody got some simple code to turn on and turn off
an LED???
please email sample code to datalines@excite.com
TIA
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim Lewis
Director of Training mailto:Jim@SynthWorks.com
SynthWorks Design Inc. http://www.SynthWorks.com
1-503-590-4787
Expert VHDL Training for Hardware Design and Verification
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Or save some fpga resources like this:For active high:
LedOut <= '1' ;
For a simple on/off with a switch:
LedOut <= SwitchIn ;
If the switch just results in turning of and off a LED used as an
indicator, there is no need to debounce it. Debounce becomes
important if the fact that the switch turns on and off many times
within a millisecond or so after it is actuated disturbs the
operation of your circuit. Something like a counter that counts
how many times the switch is operated would need debounce.
Simply turning on and off the led to follow the switch movement
does not.
Likewise, dipswitches used to set modes often do not require
debouncing. They can either be accepted as is, or in many cases
are read at one particular instant during some initialization, so
debounce is not needed. Only if the operation of the switch
causes an immediate action is the debounce needed.
Jim Lewis wrote:
For active high:
LedOut <= '1' ;
For a simple on/off with a switch:
LedOut <= SwitchIn ;
Of course you probably should debounce the switch input
and register the LedOut output. For debounce,
do a search of the newsgroup. Assume that your
switch is bouncing if it has not been stable for
anywhere from 5 ms to 15 ms.
If you bought your board, there may be a test
code that your vendor provides that does this.
Cheers,
Jim
network lines wrote:
Hello...i am new to VHDL, and learning how to
program using a Cypress CPLD.
Anybody got some simple code to turn on and turn off
an LED???
please email sample code to datalines@excite.com
TIA
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim Lewis
Director of Training mailto:Jim@SynthWorks.com
SynthWorks Design Inc. http://www.SynthWorks.com
1-503-590-4787
Expert VHDL Training for Hardware Design and Verification
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email ray@andraka.com
http://www.andraka.com
"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin,
1759
My conservative suggestion to debounce is concern over
noise causing the lifetime of the LED to be shorter.
Perhaps this is not a concern?
I know in my house some light bulbs seem to burn out
faster than others and I have always wondered if it
was due to excessive noise from the switches (look
nice, but knowing the builder they are probably
low cost).
Cheers,
Jim
actually i think it's because of the light bulb being turned on when theMy conservative suggestion to debounce is concern over
noise causing the lifetime of the LED to be shorter.
Perhaps this is not a concern?
I know in my house some light bulbs seem to burn out
faster than others and I have always wondered if it
was due to excessive noise from the switches (look
nice, but knowing the builder they are probably
low cost).
Cheers,
Jim
If the switch just results in turning of and off a LED used as an
indicator, there is no need to debounce it. Debounce becomes
important if the fact that the switch turns on and off many times
within a millisecond or so after it is actuated disturbs the
operation of your circuit. Something like a counter that counts
how many times the switch is operated would need debounce.
Simply turning on and off the led to follow the switch movement
does not.
Likewise, dipswitches used to set modes often do not require
debouncing. They can either be accepted as is, or in many cases
are read at one particular instant during some initialization, so
debounce is not needed. Only if the operation of the switch
causes an immediate action is the debounce needed.
Jim Lewis wrote:
For active high:
LedOut <= '1' ;
For a simple on/off with a switch:
LedOut <= SwitchIn ;
Of course you probably should debounce the switch input
and register the LedOut output. For debounce,
do a search of the newsgroup. Assume that your
switch is bouncing if it has not been stable for
anywhere from 5 ms to 15 ms.
If you bought your board, there may be a test
code that your vendor provides that does this.
Cheers,
Jim
network lines wrote:
Hello...i am new to VHDL, and learning how to
program using a Cypress CPLD.
Anybody got some simple code to turn on and turn off
an LED???
please email sample code to datalines@excite.com
TIA
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim Lewis
Director of Training mailto:Jim@SynthWorks.com
SynthWorks Design Inc. http://www.SynthWorks.com
1-503-590-4787
Expert VHDL Training for Hardware Design and Verification
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email ray@andraka.com
http://www.andraka.com
"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin,
1759
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim Lewis
Director of Training mailto:Jim@SynthWorks.com
SynthWorks Design Inc. http://www.SynthWorks.com
1-503-590-4787
Expert VHDL Training for Hardware Design and Verification
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--My conservative suggestion to debounce is concern over
noise causing the lifetime of the LED to be shorter.
Perhaps this is not a concern?
I know in my house some light bulbs seem to burn out
faster than others and I have always wondered if it
was due to excessive noise from the switches (look
nice, but knowing the builder they are probably
low cost).
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim Lewis
Director of Training mailto:Jim@SynthWorks.com
SynthWorks Design Inc. http://www.SynthWorks.com
1-503-590-4787
Expert VHDL Training for Hardware Design and Verification
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Light bulbs burn out faster on turn on/off cycles because the wire
resistance is lower when it is cold, and when turned on it has a surge
of current much higher than the on current.