debouncing a switch (in hardware)

I've been messing around with my own sort of development board for an Altera MAX 3064 because I have some downtime at work (I'm a coop) and wanted to teach myself some PLD stuff. I wanted ot put a manual clock button on it so I could just mess around with some simple designs to get a feel for how to use HDL's and Quartus. I have some DIPs for inputs and LEDs for outputs, everything run on 3.3V. But the I can't manage to get the clock to pulse just once when I press the button. Can anyone recomend a debouncing circuit to use for something l like this?

"Brian McFarland" <brian.mcf1985@gmail.com> wrote in message news:1152212019.602303.49750@s26g2000cwa.googlegroups.com... > I've been messing around with my own sort of development board for an > Altera MAX 3064 because I have some downtime at work (I'm a coop) and > wanted to teach myself some PLD stuff. I wanted ot put a manual clock > button on it so I could just mess around with some simple designs to > get a feel for how to use HDL's and Quartus. I have some DIPs for > inputs and LEDs for outputs, everything run on 3.3V. But the I can't > manage to get the clock to pulse just once when I press the button. > Can anyone recomend a debouncing circuit to use for something l like > this? > Best way of all is to use a single pole change over switch and a set-reset circuit (cross coupled two input nands). Guaranteed to give bounce free output without any tricky time constants/capacitor slugging/timers etc! http://www.wheelnut.plus.com/sr.gif (excuse poor drawing!) HTH Slurp

Brian McFarland wrote: > I've been messing around with my own sort of development board for an > Altera MAX 3064 because I have some downtime at work (I'm a coop) and > wanted to teach myself some PLD stuff. I wanted ot put a manual clock > button on it so I could just mess around with some simple designs to > get a feel for how to use HDL's and Quartus. I have some DIPs for > inputs and LEDs for outputs, everything run on 3.3V. But the I can't > manage to get the clock to pulse just once when I press the button. > Can anyone recomend a debouncing circuit to use for something l like > this? If you use a microswitch ( SPDT ) action (so it flips from GND to Vcc), and a regen-hold feedback (or pinkeep), this solves the bounce effects. -jg

On Thu, 06 Jul 2006 11:53:39 -0700, Brian McFarland wrote: > I've been messing around with my own sort of development board for an > Altera MAX 3064 because I have some downtime at work (I'm a coop) and > wanted to teach myself some PLD stuff. I wanted ot put a manual clock > button on it so I could just mess around with some simple designs to > get a feel for how to use HDL's and Quartus. I have some DIPs for > inputs and LEDs for outputs, everything run on 3.3V. But the I can't > manage to get the clock to pulse just once when I press the button. > Can anyone recomend a debouncing circuit to use for something l like > this? Google "switch debounce." ~Dave~

Hi - On 6 Jul 2006 11:53:39 -0700, "Brian McFarland" <brian.mcf1985@gmail.com> wrote: >I've been messing around with my own sort of development board for an >Altera MAX 3064 because I have some downtime at work (I'm a coop) and >wanted to teach myself some PLD stuff. I wanted ot put a manual clock >button on it so I could just mess around with some simple designs to >get a feel for how to use HDL's and Quartus. I have some DIPs for >inputs and LEDs for outputs, everything run on 3.3V. But the I can't >manage to get the clock to pulse just once when I press the button. >Can anyone recomend a debouncing circuit to use for something l like >this? Jack Ganssle has written extensively about this. Here's a paper that summarizes his findings and design suggestions: http://www.ganssle.com/debouncing.pdf Bob Perlman Cambrian Design Works http://www.cambriandesign.com

Bob Perlman wrote: > Hi - > > Jack Ganssle has written extensively about this. Here's a paper that > summarizes his findings and design suggestions: > > http://www.ganssle.com/debouncing.pdf On this general subject, does anyone know of a LOW PROFILE microswitch action ( SPCO / SPDT ) switch ? There are std microswitches, which tend to have a high profile, and couple of old ITT style snap switches, also ~10mm high, but nothing I have found is close to a tact button, with SPCO ? -jg

"Jim Granville" <no.spam@designtools.co.nz> wrote in message news:44ade255@clear.net.nz... > Bob Perlman wrote: >> Hi - Jack Ganssle has written extensively about this. Here's a paper >> that >> summarizes his findings and design suggestions: >> >> http://www.ganssle.com/debouncing.pdf > > On this general subject, does anyone know of a LOW PROFILE microswitch > action ( SPCO / SPDT ) switch ? > There are std microswitches, which tend to have a high profile, and > couple of old ITT style snap switches, also ~10mm high, but nothing I have > found is close to a tact button, with SPCO ? > > -jg > Here is an article in ECN about some Ultraminiature Mircroswitches from Tyco http://www.ecnmag.com/article/CA6339402.html?nid=2730&rid=1635558756 -- Greg

Gregory C. Read wrote: > "Jim Granville" <no.spam@designtools.co.nz> wrote in message > news:44ade255@clear.net.nz... > >>Bob Perlman wrote: >> >>>Hi - Jack Ganssle has written extensively about this. Here's a paper >>>that >>>summarizes his findings and design suggestions: >>> >>>http://www.ganssle.com/debouncing.pdf >> >> On this general subject, does anyone know of a LOW PROFILE microswitch >>action ( SPCO / SPDT ) switch ? >> There are std microswitches, which tend to have a high profile, and >>couple of old ITT style snap switches, also ~10mm high, but nothing I have >>found is close to a tact button, with SPCO ? >> >>-jg >> > > > Here is an article in ECN about some Ultraminiature Mircroswitches from Tyco > http://www.ecnmag.com/article/CA6339402.html?nid=2730&rid=1635558756 Thanks, yes, seen that. The microswitch market is industrial-legacy: what they call "Ultraminiature Mircroswitches" are around 12.7mm long - which is what the semiconductor sector would consider "quite large" :) -jg

Jim, Have you tried ALPS? http://www3.alps.co.jp/alpscom/ I haven't looked to see if they carry what you want; but their name immediately came to mind upon hearing your request. Rob "Jim Granville" <no.spam@designtools.co.nz> wrote in message news:44ade255@clear.net.nz... > Bob Perlman wrote: >> Hi - Jack Ganssle has written extensively about this. Here's a paper >> that >> summarizes his findings and design suggestions: >> >> http://www.ganssle.com/debouncing.pdf > > On this general subject, does anyone know of a LOW PROFILE microswitch > action ( SPCO / SPDT ) switch ? > There are std microswitches, which tend to have a high profile, and > couple of old ITT style snap switches, also ~10mm high, but nothing I have > found is close to a tact button, with SPCO ? > > -jg >

Bob Perlman wrote: > Hi - > > On 6 Jul 2006 11:53:39 -0700, "Brian McFarland" > <brian.mcf1985@gmail.com> wrote: > > >>I've been messing around with my own sort of development board for an >>Altera MAX 3064 because I have some downtime at work (I'm a coop) and >>wanted to teach myself some PLD stuff. I wanted ot put a manual clock >>button on it so I could just mess around with some simple designs to >>get a feel for how to use HDL's and Quartus. I have some DIPs for >>inputs and LEDs for outputs, everything run on 3.3V. But the I can't >>manage to get the clock to pulse just once when I press the button. >>Can anyone recomend a debouncing circuit to use for something l like >>this? > > > Jack Ganssle has written extensively about this. Here's a paper that > summarizes his findings and design suggestions: > > http://www.ganssle.com/debouncing.pdf > > Bob Perlman > Cambrian Design Works > http://www.cambriandesign.com I just finished implementing a small protoboard with 12 unbonced switches, I used a safe SRLatch type approach :-) And it works like heaven ;-)

aName wrote: > Bob Perlman wrote: > > > Hi - > > > > On 6 Jul 2006 11:53:39 -0700, "Brian McFarland" > > <brian.mcf1985@gmail.com> wrote: > > > > > >>I've been messing around with my own sort of development board for an > >>Altera MAX 3064 because I have some downtime at work (I'm a coop) and > >>wanted to teach myself some PLD stuff. I wanted ot put a manual clock > >>button on it so I could just mess around with some simple designs to > >>get a feel for how to use HDL's and Quartus. I have some DIPs for > >>inputs and LEDs for outputs, everything run on 3.3V. But the I can't > >>manage to get the clock to pulse just once when I press the button. > >>Can anyone recomend a debouncing circuit to use for something l like > >>this? > > > > > > Jack Ganssle has written extensively about this. Here's a paper that > > summarizes his findings and design suggestions: > > > > http://www.ganssle.com/debouncing.pdf > > > > Bob Perlman > > Cambrian Design Works > > http://www.cambriandesign.com > > > I just finished implementing a small protoboard with 12 unbonced > switches, I used a safe SRLatch type approach :-) > > And it works like heaven ;-) SRLatch works with SPDT, if you need to debounce SPST, which is more common, you need to have something with a timing circuit in it like the Maxim MAX6817 dual switch debouncer: http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1896 As I recall switch debouncer IC's have been around since early days of 4000 series CMOS. Have Fun, Gabor

Gabor wrote: > aName wrote: > >>Bob Perlman wrote: >> >> >>>Hi - >>> >>>On 6 Jul 2006 11:53:39 -0700, "Brian McFarland" >>><brian.mcf1985@gmail.com> wrote: >>> >>> >>> >>>>I've been messing around with my own sort of development board for an >>>>Altera MAX 3064 because I have some downtime at work (I'm a coop) and >>>>wanted to teach myself some PLD stuff. I wanted ot put a manual clock >>>>button on it so I could just mess around with some simple designs to >>>>get a feel for how to use HDL's and Quartus. I have some DIPs for >>>>inputs and LEDs for outputs, everything run on 3.3V. But the I can't >>>>manage to get the clock to pulse just once when I press the button. >>>>Can anyone recomend a debouncing circuit to use for something l like >>>>this? >>> >>> >>>Jack Ganssle has written extensively about this. Here's a paper that >>>summarizes his findings and design suggestions: >>> >>>http://www.ganssle.com/debouncing.pdf >>> >>>Bob Perlman >>>Cambrian Design Works >>>http://www.cambriandesign.com >> >> >>I just finished implementing a small protoboard with 12 unbonced >>switches, I used a safe SRLatch type approach :-) >> >>And it works like heaven ;-) > > > SRLatch works with SPDT, if you need to debounce SPST, which is more > common, you need to have something with a timing circuit in it like the > Maxim MAX6817 dual switch debouncer: > > http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1896 > > As I recall switch debouncer IC's have been around since early days > of 4000 series CMOS. > > Have Fun, > Gabor > Yes of course for SPST amd unbounced pulse you can go with something like MAX6818 (they have free samples):-) I choose SPDT and SRLatch because I wanted unbounced transitions and stables states (High Low) so I can decompose clock and other stuff ;-)

Brian McFarland schreef: > I've been messing around with my own sort of development board for an > Altera MAX 3064 because I have some downtime at work (I'm a coop) and > wanted to teach myself some PLD stuff. I wanted ot put a manual clock > button on it so I could just mess around with some simple designs to > get a feel for how to use HDL's and Quartus. I have some DIPs for > inputs and LEDs for outputs, everything run on 3.3V. But the I can't > manage to get the clock to pulse just once when I press the button. > Can anyone recomend a debouncing circuit to use for something l like > this? Hi Brain, Why don't you start messing around with the MAX II / EPM240. It comes with an internal oscillator that can be used for debouncing. Additional to this it has an schmitt trigger option on the inputs. You can misuse the design example and steel the debouce: http://altera.com/support/examples/max/exm-analog-encoder.html Karl.

Brian McFarland wrote: > I've been messing around with my own sort of development board for an > Altera MAX 3064 because I have some downtime at work (I'm a coop) and > wanted to teach myself some PLD stuff. I wanted ot put a manual clock > button on it so I could just mess around with some simple designs to > get a feel for how to use HDL's and Quartus. I have some DIPs for > inputs and LEDs for outputs, everything run on 3.3V. But the I can't > manage to get the clock to pulse just once when I press the button. > Can anyone recomend a debouncing circuit to use for something l like > this? Hi Brain, Why don't you start messing around with the MAX II / EPM240. It comes with an internal oscillator that can be used for debouncing. Additional to this it has an schmitt trigger option on the inputs. You can misuse the design example and steal the debouce: http://altera.com/support/examples/max/exm-analog-encoder.html Karl.

Similiar Articles:

debouncing a switch (in hardware) - comp.arch.fpga
I've been messing around with my own sort of development board for an Altera MAX 3064 because I have some downtime at work (I'm a coop) and wanted to ...

Debounce in Verilog? - comp.arch.fpga
debouncing a switch (in hardware) - comp.arch.fpga Debounce in Verilog? - comp.arch.fpga By "software debounce in verilog" I assume you mean "hardware debounce in verilog". ...

vhdl code for debouncing push button - comp.arch.fpga
debouncing a switch (in hardware) - comp.arch.fpga... comp.lang.vhdl That way, if you decided to change the clock later on ... Wikipedia, the free encyclopedia VHDL ...

Signal frequency is out of range - Please change timing signal ...
debouncing a switch (in hardware) - comp.arch.fpga Signal frequency is out of range - Please change timing signal ..... Signal frequency is out of range - Please change ...

change a clock to pulse in vhdl - comp.lang.vhdl
debouncing a switch (in hardware) - comp.arch.fpga change a clock to pulse in vhdl - comp.lang.vhdl That way, if you decided to change the clock later on ...

A few LatticeMico32 questions - comp.arch.fpga
Is there a reset debounce delay somewhere in the LM32 logic, or is this ... debouncing a switch (in hardware) - comp.arch.fpga A few LatticeMico32 questions - comp.arch.fpga ...

A couple of CPLD design challenges for the group - comp.arch.fpga ...
... of some kind (it should be possible to change the ... Since this is their first time using any sort of hardware ... pushbuttons and debounced using an SR based debouncer ...

Simulation of VHDL code for a vending machine - comp.arch.fpga ...
Also, assuming this is targeting real hardware ... > > If you change the booleans to std_logic, you'll need ... vhdl code for debouncing push button - comp.arch.fpga ...

Switch Debouncing - The Lab Book Pages
Hardware RNG; PC Parallel Port; PC Serial Port; Scopes; Switch Debouncing; FPGAs; Metalwork ... Switch Debouncing. Switch debouncing is one of those things ...

How to debounce a switch - ALL ELECTRIC KITCHEN
Also useful for resetting microprocessors which is similar to the switch debounce. But we're getting ahead of ourselves. Above is the full debounce circuit using ...

7/18/2012 9:53:50 PM