Re: [piclist] Pull up resistors ?


Aug 22, 2004

 


----------------------------

#6866 Aug 22, 2004

I have a weird issue. I've used the hardware I2C on the PIC

16F77 with no problems between multiple chips using 2.7K to 4.7K

pull up resistors very successfully. However when using the 16F877A

I'm finding that I2C isn't reliable at all unless I use 22K to 47K

pull ups. Weird huh? Now lets get weirder, If I put a 16F77 into

the I2C circuit EVEN IF IT ISN"T BEING USED the I2C channels start

working properly again! I'm using essentially the same code on all

of the chips too.



Has anyone seen this totally wrong behavior before, and if you have,

did you ever discover what was going on?



Baffled,

DLC



----------------------------

#6867 Aug 22, 2004

I remember off the top of my head thatthere is an erata doc on this that helped me when I hit the same problem with18f452 comms.  The high value that you’reusing seems a bit suspect as I use 1k and it work very well in noisyenvironments.  I also remember that theclk and data must be put into an input/output state of a certain combination butI am not sure not exactly what so check in your data manual.  I use the chip on 40meg and with 400k commsand it works well so if you have any more hassles then shoot!  

From: Dennis Clark[mailto:dlc@...]

Sent: Monday, 23 August 2004 15:46

To: piclist@yahoogroups.com

Subject: [piclist] 16F877A and I2Cpull up resistors

   I have a weird issue.  I've used the hardware I2C on thePIC

16F77 with no problems between multiple chipsusing 2.7K to 4.7K

pull up resistors very successfully.  Howeverwhen using the 16F877A

I'm finding that I2C isn't reliable at all unlessI use 22K to 47K

pull ups.  Weird huh?  Now lets getweirder, If I put a 16F77 into

the I2C circuit EVEN IF IT ISN"T BEING USEDthe I2C channels start

working properly again!  I'm usingessentially the same code on all

of the chips too.



  Has anyone seen this totally wrong behaviorbefore, and if you have,

did you ever discover what was going on? 



Baffled,

DLC







tounsubscribe, go to www.yahoogroups.comand follow the instructions



----------------------------

#6868 Aug 23, 2004

On Mon, 23 Aug 2004, Dennis Clark wrote:

>

> I have a weird issue. I've used the hardware I2C on the PIC

> 16F77 with no problems between multiple chips using 2.7K to 4.7K

> pull up resistors very successfully. However when using the 16F877A

> I'm finding that I2C isn't reliable at all unless I use 22K to 47K

> pull ups.



This make me thinking that parasitic IO capacitance of 877A is 10 times

greater than 877. Which can't be true.





Weird huh? Now lets get weirder, If I put a 16F77 into > the I2C circuit EVEN IF IT ISN"T BEING USED the I2C channels start

> working properly again! I'm using essentially the same code on all

> of the chips too.



So, you have in i2c circuit the unused CLK and SD pins of an 877.

Definitely is a wrong wired i2c bus. How long, how many cips, where is the

pullup resistor ? etc.

Does the i2c is exactly the same in 877 and 877A ?



best regards,

Vasile



----------------------------

#6871 Aug 23, 2004

How long are your i2c-wires? Keep them very short. How

good is your power-supply on the i2c-bus? As I read

it, it looks like the 877A has problems pulling the

lines low, except with high-value resistors. Strange,

since all types of PICs can sink 25mA on their pins,

and that should be more than enough to pull a line

down with a 2.2k resistor. How is your solderwork?



Kees

--- Dennis Clark dlc@...> wrote:

> I have a weird issue. I've used the hardware I2C

> on the PIC

> 16F77 with no problems between multiple chips using

> 2.7K to 4.7K

> pull up resistors very successfully. However when

> using the 16F877A

> I'm finding that I2C isn't reliable at all unless I

> use 22K to 47K

> pull ups. Weird huh? Now lets get weirder, If I

> put a 16F77 into

> the I2C circuit EVEN IF IT ISN"T BEING USED the I2C

> channels start

> working properly again! I'm using essentially the

> same code on all

> of the chips too.

>

> Has anyone seen this totally wrong behavior

> before, and if you have,

> did you ever discover what was going on?

>

> Baffled,

> DLC

>

>









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----------------------------

#6882 Aug 28, 2004

Kees,



My solderwork is fine. My wires are about 25cm(10 inches) and

my power supply is fine. I've totally wrung this out about 20

times and just don't see what is going wrong. I'm using the

hardware I2C, not a bit bang, so that is out. I KNOW my resistor

values and the cables that I've made too. Other folks have seen

this same issue on their boards made by the same folks - So this

doesn't leave out poor board design, but I've checked out the

schematics and traces and they are all what they say they are

and what they should be too.



Darn, I was hoping for someone seeing an appnote that I've missed!



DLC

--- In piclist@yahoogroups.com, Kees Stenekes knalkeez@y...> wrote:

> How long are your i2c-wires? Keep them very short. How

> good is your power-supply on the i2c-bus? As I read

> it, it looks like the 877A has problems pulling the

> lines low, except with high-value resistors. Strange,

> since all types of PICs can sink 25mA on their pins,

> and that should be more than enough to pull a line

> down with a 2.2k resistor. How is your solderwork?

>

> Kees

> --- Dennis Clark dlc@f...> wrote:

>

> > I have a weird issue. I've used the hardware I2C

> > on the PIC

> > 16F77 with no problems between multiple chips using

> > 2.7K to 4.7K

> > pull up resistors very successfully. However when

> > using the 16F877A

> > I'm finding that I2C isn't reliable at all unless I

> > use 22K to 47K

> > pull ups. Weird huh? Now lets get weirder, If I

> > put a 16F77 into

> > the I2C circuit EVEN IF IT ISN"T BEING USED the I2C

> > channels start

> > working properly again! I'm using essentially the

> > same code on all

> > of the chips too.

> >

> > Has anyone seen this totally wrong behavior

> > before, and if you have,

> > did you ever discover what was going on?

> >

> > Baffled,

> > DLC

> >

> >

>

>

>

> ..

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----------------------------

#6883 Aug 28, 2004

Vasile,

> On Mon, 23 Aug 2004, Dennis Clark wrote:

>

> >

> > I have a weird issue. I've used the hardware I2C on the PIC

> > 16F77 with no problems between multiple chips using 2.7K to 4.7K

> > pull up resistors very successfully. However when using the 16F877A

> > I'm finding that I2C isn't reliable at all unless I use 22K to 47K

> > pull ups.

>

> This make me thinking that parasitic IO capacitance of 877A is 10

times > greater than 877. Which can't be true.



I didn't think so either, but I've seen other undocumented

incompatabilities between the '877 and 877a... >

> Weird huh? Now lets get weirder, If I put a 16F77 into

> > the I2C circuit EVEN IF IT ISN"T BEING USED the I2C channels start

> > working properly again! I'm using essentially the same code on all

> > of the chips too.

>

> So, you have in i2c circuit the unused CLK and SD pins of an 877.

> Definitely is a wrong wired i2c bus. How long, how many cips, where

is the > pullup resistor ? etc.

> Does the i2c is exactly the same in 877 and 877A ?



I've got three chips in the circuit (including the '877) or just

two chips in the circuit (using only '877As). The code is exactly

the same on all the chips.



thanks,

DLC

> best regards,

> Vasile



----------------------------

#6884 Aug 28, 2004

Thanks, I've posted all that I have on the issue and I'm confused.

Really confused as to what is going on here...



regards,

DLC





--- In piclist@yahoogroups.com, "martin de lange" martin_de_lange@x>

wrote: > I remember off the top of my head that there is an erata doc on this

that > helped me when I hit the same problem with 18f452 comms. The high value

> that you're using seems a bit suspect as I use 1k and it work very

well in > noisy environments. I also remember that the clk and data must be

put into > an input/output state of a certain combination but I am not sure not

exactly > what so check in your data manual. I use the chip on 40meg and with

400k > comms and it works well so if you have any more hassles then shoot!

>

> _____

>

> From: Dennis Clark [mailto:dlc@f...]

> Sent: Monday, 23 August 2004 15:46

> To: piclist@yahoogroups.com

> Subject: [piclist] 16F877A and I2C pull up resistors

>

> I have a weird issue. I've used the hardware I2C on the PIC

> 16F77 with no problems between multiple chips using 2.7K to 4.7K

> pull up resistors very successfully. However when using the 16F877A

> I'm finding that I2C isn't reliable at all unless I use 22K to 47K

> pull ups. Weird huh? Now lets get weirder, If I put a 16F77 into

> the I2C circuit EVEN IF IT ISN"T BEING USED the I2C channels start

> working properly again! I'm using essentially the same code on all

> of the chips too.

>

> Has anyone seen this totally wrong behavior before, and if you have,

> did you ever discover what was going on?

>

> Baffled,

> DLC

>

>

>

> to unsubscribe, go to www.yahoogroups.com and follow the

instructions >

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----------------------------

#6906 Aug 30, 2004

FIY. I currently have I2C set up between a 16F877A and a 16F873 using

2.2 Kohm pullups on the clock and data lines. The 16F877A is the

master. It works on both 100 KHz and 400 KHz.



I can only send one byte in a message, but I think that's a problem

with my CCS compiler. I have never heard of anyone getting I2C slave

mode to work with C (only assembly).



Maybe this info will help you a little.



BRW

--- In piclist@yahoogroups.com, "Dennis Clark" dlc@f...> wrote:

> I have a weird issue. I've used the hardware I2C on the PIC

> 16F77 with no problems between multiple chips using 2.7K to 4.7K

> pull up resistors very successfully. However when using the 16F877A

> I'm finding that I2C isn't reliable at all unless I use 22K to 47K

> pull ups. Weird huh? Now lets get weirder, If I put a 16F77 into

> the I2C circuit EVEN IF IT ISN"T BEING USED the I2C channels start

> working properly again! I'm using essentially the same code on all

> of the chips too.

>

> Has anyone seen this totally wrong behavior before, and if you

have,

> did you ever discover what was going on?

>

> Baffled,

> DLC







----------------------------

#6908 Aug 30, 2004

I'm reading spec sheets, but the first thing I would do, would be to

hang a scope on that puppy. I assume you can't or you saw nothing

unusual.



Chad



--- Bennet Williams bennet@...> wrote:

> FIY. I currently have I2C set up between a 16F877A and a 16F873 using

>

> 2.2 Kohm pullups on the clock and data lines. The 16F877A is the

> master. It works on both 100 KHz and 400 KHz.

>

> I can only send one byte in a message, but I think that's a problem

> with my CCS compiler. I have never heard of anyone getting I2C slave

> mode to work with C (only assembly).

>

> Maybe this info will help you a little.

>

> BRW

>

> --- In piclist@yahoogroups.com, "Dennis Clark" dlc@f...> wrote:

> > I have a weird issue. I've used the hardware I2C on the PIC

> > 16F77 with no problems between multiple chips using 2.7K to 4.7K

> > pull up resistors very successfully. However when using the

> 16F877A

> > I'm finding that I2C isn't reliable at all unless I use 22K to 47K

> > pull ups. Weird huh? Now lets get weirder, If I put a 16F77 into

> > the I2C circuit EVEN IF IT ISN"T BEING USED the I2C channels start

> > working properly again! I'm using essentially the same code on all

> > of the chips too.

> >

> > Has anyone seen this totally wrong behavior before, and if you

> have,

> > did you ever discover what was going on?

> >

> > Baffled,

> > DLC

>

>





=====

My software has no bugs, only undocumented features.









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----------------------------

#6920 Aug 31, 2004

Obviously this is not right. I'm curious how you put the 16F77 in the

circuit. If I had to guess, you have a ground problem causing some

level shifting. Just a guess, with little info. Good luck.



Chad



--- Dennis Clark dlc@...> wrote:

> Thanks, I've posted all that I have on the issue and I'm confused.

> Really confused as to what is going on here...

>

> regards,

> DLC

>

>

> --- In piclist@yahoogroups.com, "martin de lange" martin_de_lange@x>

> wrote:

> > I remember off the top of my head that there is an erata doc on

> this

> that

> > helped me when I hit the same problem with 18f452 comms. The high

> value

> > that you're using seems a bit suspect as I use 1k and it work very

> well in

> > noisy environments. I also remember that the clk and data must be

> put into

> > an input/output state of a certain combination but I am not sure

> not

> exactly

> > what so check in your data manual. I use the chip on 40meg and

> with

> 400k

> > comms and it works well so if you have any more hassles then shoot!

> >

> > _____

> >

> > From: Dennis Clark [mailto:dlc@f...]

> > Sent: Monday, 23 August 2004 15:46

> > To: piclist@yahoogroups.com

> > Subject: [piclist] 16F877A and I2C pull up resistors

> >

> > I have a weird issue. I've used the hardware I2C on the PIC

> > 16F77 with no problems between multiple chips using 2.7K to 4.7K

> > pull up resistors very successfully. However when using the

> 16F877A

> > I'm finding that I2C isn't reliable at all unless I use 22K to 47K

> > pull ups. Weird huh? Now lets get weirder, If I put a 16F77 into

> > the I2C circuit EVEN IF IT ISN"T BEING USED the I2C channels start

> > working properly again! I'm using essentially the same code on all

> > of the chips too.

> >

> > Has anyone seen this totally wrong behavior before, and if you

> have,

> > did you ever discover what was going on?

> >

> > Baffled,

> > DLC





=====

My software has no bugs, only undocumented features.







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----------------------------

#10047 Apr 21, 2006

DoH!



I'm telling you my head hurts......



I was trying to work out the value of a thermistor to order a spare,

its got a resistor in parallel with it, of (according to meter) 17.2k

(17200ohms)



At 0degress C its reading (therm+resistor combination) is 4237 ohms

At 100 degrees C its reading 346 ohms



Everytime I work it out I get a different reading when I double check

it by doinfthe same sum backwards.



I tried an online one but it crashed, gave a reading with an exponent (E+3 etc)

or kept saying 1856 ohms, which it cant be...



I had not realised how bad I had got at maths having a pc etc always by my side!









--







Lez



- Looking for early starwars (episode 4, original starwars)

recordings, even pirate

-

- I dont need your originals just some information about running time

- and scene cut points

-

-

- also looking for a car, silver or white, 4 doors -

- diesel with a bosch pump, abs and pas -

- aircon would be nice, and not a ford -







----------------------------

#10048 Apr 21, 2006

Just measure the thermistor alone, at 20 degC...that'll give you its nominalvalue.

Not a foolproof way of identifying it though as all thermistors arenot the

same in terms of temp/value characteristics.Lez wrote: DoH!I'm telling you my head hurts......I was trying to work out the value of a thermistor to order a spare,

its got a resistor in parallel with it, of (according to meter) 17.2k

(17200ohms)At 0degress C its reading (therm+resistor combination) is 4237 ohms

At 100 degrees C its reading 346 ohmsEverytime I work it out I get a different reading when I double check

it by doinfthe same sum backwards.I tried an online one but it crashed, gave a reading with an exponent(E+3 etc)

or kept saying 1856 ohms, which it cant be...I had not realised how bad I had got at maths having a pc etc alwaysby my side!

 

 

 --

 

 Lez- Looking for early starwars (episode 4, original starwars)

recordings, even pirate

-

- I dont need your originals just some information about running time

- and scene cut points

-

-

- also looking for a car, silver or white, 4 doors -

- diesel with a bosch pump, abs and pas  -

- aircon would be nice, and not a ford      -



--

*******************************************

VISIT MY HOME PAGE:

home.online.no/~eikarlse/index.htm>

LAST UPDATED: 23/08/2003

*******************************************

Regards

Eirik Karlsen

 



----------------------------

#10049 Apr 21, 2006

Its set in epoxy and part of a bigger block, so I Cant dig/drill it out without fear of further damage.



Just got back from taking wife shopping (please no pity) so when myhead stops spinning I will get the calculator out and try again.........

 

I'm telling you my head hurts......I was trying to work out the value of a thermistor to order a spare,

its got a resistor in parallel with it, of (according to meter) 17.2k

(17200ohms)At 0degress C its reading (therm+resistor combination) is 4237 ohms

At 100 degrees C its reading 346 ohmsEverytime I work it out I get a different reading when I double check

it by doinfthe same sum backwards.I tried an online one but it crashed, gave a reading with an exponent(E+3 etc)

or kept saying 1856 ohms, which it cant be...I had not realised how bad I had got at maths having a pc etc alwaysby my side!

 

 







--



Lez

- Looking for early starwars (episode 4, original starwars) recordings, even pirate-- I dont need your originals just some information about running time

- and scene cut points-



----------------------------

#10050 Apr 21, 2006

--- In piclist@yahoogroups.com, Lez lez.briddon@...> wrote: >

> Its set in epoxy and part of a bigger block, so I Cant dig/drill it out

> without fear of further damage.

>

> Just got back from taking wife shopping (please no pity) so when my head

> stops spinning I will get the calculator out and try again.........

>

>

> I'm telling you my head hurts......

> >

> > I was trying to work out the value of a thermistor to order a spare,

> > its got a resistor in parallel with it, of (according to meter) 17.2k

> > (17200ohms)

> >

> > At 0degress C its reading (therm+resistor combination) is 4237 ohms

> > At 100 degrees C its reading 346 ohms

> >

> > Everytime I work it out I get a different reading when I double check

> > it by doinfthe same sum backwards.

> >

> > I tried an online one but it crashed, gave a reading with an

exponent (E+3 > > etc)

> > or kept saying 1856 ohms, which it cant be...

> >

> > I had not realised how bad I had got at maths having a pc etc

always by my > > side!

> >

> >

> >

> >

> --

>

>

>

> Lez

>

> - Looking for early starwars (episode 4, original starwars)

recordings, even > pirate

> -

> - I dont need your originals just some information about running time

> - and scene cut points

> -

>



I uploaded an Excel file graph of the ideal slope the thermister would

have with the data points you gave.



----------------------------

#10051 Apr 22, 2006

Big Thanks! just woke up so the day must be off to a good start already!







On 22/04/06, john j_funk1425@...> wrote:

> --- In piclist@yahoogroups.com, Lez lez.briddon@...> wrote:

> >

> > Its set in epoxy and part of a bigger block, so I Cant dig/drill it out

> > without fear of further damage.

> >

> > Just got back from taking wife shopping (please no pity) so when my head

> > stops spinning I will get the calculator out and try again.........

> >

> >

> > I'm telling you my head hurts......

> > >

> > > I was trying to work out the value of a thermistor to order a spare,

> > > its got a resistor in parallel with it, of (according to meter) 17.2k

> > > (17200ohms)

> > >

> > > At 0degress C its reading (therm+resistor combination) is 4237 ohms

> > > At 100 degrees C its reading 346 ohms

> > >

> > > Everytime I work it out I get a different reading when I double check

> > > it by doinfthe same sum backwards.

> > >

> > > I tried an online one but it crashed, gave a reading with an

> exponent (E+3

> > > etc)

> > > or kept saying 1856 ohms, which it cant be...

> > >

> > > I had not realised how bad I had got at maths having a pc etc

> always by my

> > > side!

> > >

> > >

> > >

> > >

> > --

> >

> >

> >

> > Lez

> >

> > - Looking for early starwars (episode 4, original starwars)

> recordings, even

> > pirate

> > -

> > - I dont need your originals just some information about running time

> > - and scene cut points

> > -

> >

>

> I uploaded an Excel file graph of the ideal slope the thermister would

> have with the data points you gave.

>

>

>

>

>

>

> to unsubscribe, go to www.yahoogroups.com and follow the instructions

> Yahoo! Groups Links

>

>

>

>

>

>

>

>





--







Lez



- Looking for early starwars (episode 4, original starwars)

recordings, even pirate

-

- I dont need your originals just some information about running time

- and scene cut points

-

-

- also looking for a car, silver or white, 4 doors -

- diesel with a bosch pump, abs and pas -

- aircon would be nice, and not a ford -







----------------------------

#10249 Jan 1 8:17 AM

pic16F88, using dip, tactile, and toggle switches what size resistors

are recommended for pullups? Would 10k be ok for this? From what I

understand, some F88 pins has build in resistors built in?

thanks

bill



----------------------------

#10250 Jan 1 10:05 AM

Hi Bill,



10K should work fine.



Alan KM6VV



wdavis364 wrote:

>pic16F88, using dip, tactile, and toggle switches what size resistors

>are recommended for pullups? Would 10k be ok for this? From what I

>understand, some F88 pins has build in resistors built in?

>thanks

>bill

>

>

>



----------------------------

#10251 Jan 1 10:39 AM

Thanks Alan----- Original Message -----From:Alan KM6VVTo: piclist@yahoogroups.comSent: Monday, January 01, 2007 12:05PMSubject: Re: [piclist] Pull up resistors?

Hi Bill,

10K should work fine.

Alan KM6VV

wdavis364wrote:

>pic16F88, using dip, tactile, and toggle switches what sizeresistors >are recommended for pullups? Would 10k be ok for this? Fromwhat I >understand, some F88 pins has build in resistors builtin?>thanks>bill>> >



----------------------------

#10252 Jan 1 10:50 AM

I usually use a 10k with a .1uf ceramic cap placed as close to the pin as

you can to decouple it.

Jim Cullins

Sound Logic ----- Original Message -----

From: "wdavis364" wdavis364@...>

To: piclist@yahoogroups.com>

Sent: Monday, January 01, 2007 10:17 AM

Subject: [piclist] Pull up resistors ?





> pic16F88, using dip, tactile, and toggle switches what size resistors

> are recommended for pullups? Would 10k be ok for this? From what I

> understand, some F88 pins has build in resistors built in?

> thanks

> bill

>

>

>

>

> to unsubscribe, go to www.yahoogroups.com and follow the

> instructions

> Yahoo! Groups Links

>

>

>



----------------------------

#10253 Jan 1 1:16 PM

Thanks Jim, I have .1uf coming off the supply line.The .1uf is located on the supply side of the bank of switches (5) that connectsto the Pic. Will this work ok? thanks ----- Original Message -----From:JCullinsTo: piclist@yahoogroups.comSent: Monday, January 01, 2007 12:50PMSubject: Re: [piclist] Pull up resistors?

I usually use a 10k with a .1uf ceramic cap placed as close to the pin as

you can to decouple it.Jim CullinsSound Logic----- OriginalMessage ----- From: "wdavis364" wdavis364@texoma. net>To:piclist@yahoogroups .com>Sent:Monday, January 01, 2007 10:17 AMSubject: [piclist] Pull up resistors?

> pic16F88, using dip, tactile, and toggle switches what sizeresistors> are recommended for pullups? Would 10k be ok for this? Fromwhat I> understand, some F88 pins has build in resistors builtin?> thanks> bill>>>>> tounsubscribe, go to www.yahoogro ups.com andfollow the > instructions> Yahoo! GroupsLinks>>>



----------------------------

#10254 Jan 1 2:42 PM

--- In piclist@yahoogroups.com, "Bill Davis" wdavis364@...> wrote: >

> Thanks Jim, I have .1uf coming off the supply line. The .1uf is

located on the supply side of the bank of switches (5) that connects

to the Pic. Will this work ok? > thanks



Bill,



Different thing.. The decoupling capacitor between Vcc and ground is

for noise suppression. The capacitor on the input does this also but

it is really there to help debounce the switch contacts.



Yes, PORTB has internal pull-ups - see the second paragraph of

section 5.2 of the datasheet. You have to turn them on as described.



You may find some heavy duty switches don't switch well without some

serious current. You could wind up having to use values as low as

470 ohms for pull-up. But, more often than not, 10k will work. I

typically use 4.7k for no particular reason.



Richard



----------------------------

#10255 Jan 1 3:35 PM

   Good reply Richard.Yes the decoupling form the power supply is a must withthe pic butthe one I was talking about is as Richard stated fordebouncing the switch.So you need to put one on each input that has a switch onit.JimOn 1/1/2007 4:42:59 PM, rtstofer (rstofer@...) wrote: > --- In

piclist@yahoogroups.com, "BillDavis" wdavis364@...> wrote: > >> > Thanks Jim, I have

.1uf coming off the supply line. The .1uf is > located on the supply side

of the bank of switches (5) that connects > to the Pic. Will this work

ok? > > thanks> > Bill,> > Different

thing..  The decoupling capacitor between Vcc and ground is > for

noise suppression.  The capacitor on the input does this also but >

it is really there to help debounce the switch contacts. > > Yes,

PORTB has internal pull-ups - see the second paragraph of > section 5.2 of

the datasheet.  You have to turn them on as described. > > You

may find some heavy duty switches don't switch well without some > serious

current.  You could wind up having to use values as low as > 470 ohms

for pull-up.  But, more often than not, 10k will work.  I >

typically use 4.7k for no particular reason. > > Richard>

> > > > to unsubscribe, go to href="www.yahoogroups.comwww.yahoogroups.com and follow theinstructions > Yahoo! Groups Links> > *> To visit

your group on the web, go to: > href="groups.yahoo.com/group/piclist/groups.yahoo.com/group/piclist/ >

> *> Your email settings:> Individual Email |

Traditional > > *







----------------------------

#10256 Jan 1 4:10 PM

Thanks Richard, good to hear from you again. I'llgo the 10k route and check the datasheet on portb pull-ups. bill----- Original Message -----From:rtstoferTo: piclist@yahoogroups.comSent: Monday, January 01, 2007 4:42PMSubject: [piclist] Re: Pull up resistors?

--- In piclist@yahoogroups .com, "BillDavis" wdavis364@. ..> wrote:>> Thanks Jim, I have.1uf coming off the supply line. The .1uf is located on the supply side ofthe bank of switches (5) that connects to the Pic. Will this work ok?

> thanks

Bill,

Different thing.. The decouplingcapacitor between Vcc and ground is for noise suppression. The capacitoron the input does this also but it is really there to help debounce theswitch contacts.

Yes, PORTB has internal pull-ups - see the secondparagraph of section 5.2 of the datasheet. You have to turn them on asdescribed.

You may find some heavy duty switches don't switch wellwithout some serious current. You could wind up having to use values aslow as 470 ohms for pull-up. But, more often than not, 10k will work. I

typically use 4.7k for no particularreason.

Richard



----------------------------

#10257 Jan 1 4:18 PM

Thanks Jim, I'll add them in. ----- Original Message -----From:JCullinsTo: piclist@yahoogroups.comSent: Monday, January 01, 2007 5:35PMSubject: Re: [piclist] Re: Pull upresistors ?



   Good reply Richard.Yes the decoupling form the power supply is a must withthe pic butthe one I was talking about is as Richard stated fordebouncing the switch.So you need to put one on each input that has a switchon it.JimOn 1/1/2007 4:42:59 PM, rtstofer (rstofer@pacbell. net) wrote:>--- In piclist@yahoogroups .com, "BillDavis" wdavis364@.. .> wrote:> >> > Thanks Jim,I have .1uf coming off the supply line. The .1uf is> located on thesupply side of the bank of switches (5) that connects> to the Pic. Willthis work ok?> > thanks> > Bill,> >Different thing..  The decoupling capacitor between Vcc and groundis> for noise suppression.  The capacitor on the input does thisalso but> it is really there to help debounce the switchcontacts.> > Yes, PORTB has internal pull-ups - see the secondparagraph of> section 5.2 of the datasheet.  You have to turn themon as described.> > You may find some heavy duty switches don'tswitch well without some> serious current.  You could wind uphaving to use values as low as> 470 ohms for pull-up.  But, moreoften than not, 10k will work.  I> typically use 4.7k for noparticular reason.> > Richard> > > >

> to unsubscribe, go to www.yahoogro ups.com andfollow the instructions> Yahoo! Groups Links> > *>To visit your group on the web, go to:> groups. yahoo.com/ group/piclist/>

> *> Your email settings:> Individual Email |Traditional> > *



----------------------------

#10258 Jan 1 4:32 PM

What is your project?It is nice to hear what others are doing with thePIC.Do you porgram with C , BASIC , or assemaly ?JimOn 1/1/2007 6:18:06 PM, Bill Davis (wdavis364@...) wrote: >

Thanks Jim, > I'll add them in.> > ----- Original Message

----- > From: JCullins [link: href="mailto:james_cullins@...mailto:james_cullins@...] >

To: piclist@yahoogroups.com >

Sent: Monday, January 01, 2007 5:35 PM > Subject: Re: [piclist] Re: Pull

up resistors ? > > > > Good reply Richard.>

Yes the decoupling form the power supply is a must with the pic but > the

one I was talking about is as Richard stated for debouncing the switch. >

So you need to put one on each input that has a switch on it. >

Jim > On 1/1/2007 4:42:59 PM, rtstofer (href="mailto:rstofer@...rstofer@... [link: mailto:rstofer@...])wrote: > > --- In href="mailto:piclist@yahoogroups.compiclist@yahoogroups.com, "Bill Davis"wdavis364@...> wrote: > > >> > > Thanks Jim, I

have .1uf coming off the supply line. The .1uf is > > located on the

supply side of the bank of switches (5) that connects > > to the Pic.

Will this work ok? > > > thanks> >> >

Bill, > >> > Different thing.. The decoupling capacitor

between Vcc and ground is > > for noise suppression. The capacitor on

the input does this also but > > it is really there to help debounce

the switch contacts. > >> > Yes, PORTB has internal pull-ups

- see the second paragraph of >



----------------------------

#10259 Jan 1 5:29 PM

    Program in C, I'm wanting to acontrol board to test stepper motors. The idea is to be able to activate a pushswitch to add say in 100 revs increments (counting as I go) until the motor getsrough than I would activate  push switch to decrease the speed in 5 or 10revs to find where the motor run at it smoothest. At this point I wouldtweak  the driver to improve this. Then maybe try another driver forcomparison. I know to some this may seem a waste of time, but it is fun for meand a way for learning about all this.thanks for your interest and maybe yourthoughts on this.bill ----- Original Message -----From:JCullinsTo: piclist@yahoogroups.comSent: Monday, January 01, 2007 6:32PMSubject: Re: [piclist] Re: Pull upresistors ?



What is your project?It is nice to hear what others are doing with thePIC.Do you porgram with C , BASIC , or assemaly?JimOn 1/1/2007 6:18:06 PM, Bill Davis (wdavis364@texoma. net)wrote:> Thanks Jim,> I'll add them in.> > -----Original Message -----> From: JCullins [link: mailto:james_ cullins@sbcgloba l.net]>To: piclist@yahoogroups .com>Sent: Monday, January 01, 2007 5:35 PM> Subject: Re: [piclist] Re: Pullup resistors ?> > > > Good reply Richard.>Yes the decoupling form the power supply is a must with the pic but>the one I was talking about is as Richard stated for debouncing theswitch.> So you need to put one on each input that has a switch onit.> Jim> On 1/1/2007 4:42:59 PM, rtstofer (rstofer@pacbell. net [link: mailto:rstofer@ pacbell.net])wrote:> > --- In piclist@yahoogroups .com, "BillDavis" wdavis364@.. .> wrote:> > >> > >Thanks Jim, I have .1uf coming off the supply line. The .1uf is> >located on the supply side of the bank of switches (5) that connects>> to the Pic. Will this work ok?> > > thanks>>> > Bill,> >> > Different thing.. Thedecoupling capacitor between Vcc and ground is> > for noisesuppression. The capacitor on the input does this also but> > it isreally there to help debounce the switch contacts.> >> >Yes, PORTB has internal pull-ups - see the second paragraph of>







----------------------------

#10260 Jan 1 5:22 PM

10k is what I typically use. PORTB, on most, if not all, PICs have weak

pull-ups that can be enabled in software. Read the PORTB portion of the

datasheet for more info.



Harold

> pic16F88, using dip, tactile, and toggle switches what size resistors

> are recommended for pullups? Would 10k be ok for this? From what I

> understand, some F88 pins has build in resistors built in?

> thanks

> bill

>

>

>





--

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opportunities available!



----------------------------

#10261 Jan 1 5:58 PM

Thanks for the information.bill----- Original Message -----From:HaroldHallikainenTo: piclist@yahoogroups.comSent: Monday, January 01, 2007 7:22PMSubject: Re: [piclist] Pull up resistors?

10k is what I typically use. PORTB, on most, if not all, PICs haveweakpull-ups that can be enabled in software. Read the PORTB portion ofthedatasheet for more info.

Harold

> pic16F88, using dip,tactile, and toggle switches what size resistors> are recommended forpullups? Would 10k be ok for this? From what I> understand, some F88pins has build in resistors built in?> thanks>bill>>>

-- FCC Rules Updated Daily at www.hallikai nen.com -Advertisingopportunities available!



----------------------------

#10262 Jan 1 6:10 PM

Thanks for sharing.I have designed  testers for steppers mostly toexercise machines that are inproduction to make sure the machine is set up properlymechanically.I agree a lot of what we do is for fun...  do itmyself. But you are correct every thing you do you learn something. Sometimeswhat not to do. (:-)JimOn 1/1/2007 7:29:26 PM, Bill Davis (wdavis364@...) wrote: >

Program in C, > I'm wanting to a control board to test stepper motors. The

idea is to be able to activate a push switch to add say in 100 revs increments(counting as I go) until the motor gets rough than I would activate push switchto decrease the speed in 5 or 10 revs to find where the motor run at itsmoothest. At this point I would tweak the driver to improve this. Then maybetry another driver for comparison. I know to some this may seem a waste of time,but it is fun for me and a way for learning about all this. > thanks for

your interest and maybe your thoughts on this. > bill> -----

Original Message ----- > From: JCullins [link: href="mailto:james_cullins@...mailto:james_cullins@...] >

To: piclist@yahoogroups.com >

Sent: Monday, January 01, 2007 6:32 PM > Subject: Re: [piclist] Re: Pull

up resistors ? > > > > What is your project?>

It is nice to hear what others are doing with the PIC. > Do you porgram

with C , BASIC , or assemaly ? > Jim> On 1/1/2007 6:18:06 PM, Bill

Davis (wdavis364@... [link: mailto:wdavis364@...])wrote: > > Thanks Jim,> > I'll> add them in.>>> > ----- Original Message -----> > From: JCullins

[link: mailto:james_cullins@...] >> To: href="mailto:piclist@yahoogrouppiclist@yahoogroup



----------------------------

#10263 Jan 1 5:53 PM

A capacitor across the switch (or between the +5V and the switch) may weld

contacts on some switches when the switch closes. This is especially the

case with reed switches and membrane switches. I'd do debounce in software

instead of hardware.



Harold

> Thanks Jim, I have .1uf coming off the supply line. The .1uf is located on

> the supply side of the bank of switches (5) that connects to the Pic. Will

> this work ok?

> thanks

> ----- Original Message -----

> From: JCullins

> To: piclist@yahoogroups.com

> Sent: Monday, January 01, 2007 12:50 PM

> Subject: Re: [piclist] Pull up resistors ?

>

>

> I usually use a 10k with a .1uf ceramic cap placed as close to the pin

> as

> you can to decouple it.

> Jim Cullins

> Sound Logic

> ----- Original Message -----

> From: "wdavis364" wdavis364@...>

> To: piclist@yahoogroups.com>

> Sent: Monday, January 01, 2007 10:17 AM

> Subject: [piclist] Pull up resistors ?

>

> > pic16F88, using dip, tactile, and toggle switches what size resistors

> > are recommended for pullups? Would 10k be ok for this? From what I

> > understand, some F88 pins has build in resistors built in?

> > thanks

> > bill

> >

> >

> >

> >

> > to unsubscribe, go to www.yahoogroups.com and follow the

> > instructions

> > Yahoo! Groups Links

> >

> >

> >

>

>

>

>





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opportunities available!



----------------------------

#10264 Jan 1 8:08 PM

Debounce in software? I got some reading to dohere.bill----- Original Message -----From:HaroldHallikainenTo: piclist@yahoogroups.comSent: Monday, January 01, 2007 7:53PMSubject: Re: [piclist] Pull up resistors?

A capacitor across the switch (or between the +5V and the switch) mayweldcontacts on some switches when the switch closes. This is especiallythecase with reed switches and membrane switches. I'd do debounce insoftwareinstead of hardware.

Harold

> Thanks Jim, I have.1uf coming off the supply line. The .1uf is located on> the supplyside of the bank of switches (5) that connects to the Pic. Will> thiswork ok?> thanks> ----- Original Message -----> From:JCullins> To: piclist@yahoogroups .com>Sent: Monday, January 01, 2007 12:50 PM> Subject: Re: [piclist] Pull upresistors ?>>> I usually use a 10k with a .1uf ceramiccap placed as close to the pin> as> you can to decoupleit.> Jim Cullins> Sound Logic> ----- Original Message-----> From: "wdavis364" wdavis364@texoma. net>>To: piclist@yahoogroups .com>>Sent: Monday, January 01, 2007 10:17 AM> Subject: [piclist] Pull upresistors ?>> > pic16F88, using dip, tactile, and toggleswitches what size resistors> > are recommended for pullups? Would10k be ok for this? From what I> > understand, some F88 pins hasbuild in resistors built in?> > thanks> > bill>>> >> >> >> > to unsubscribe, go towww.yahoogro ups.com andfollow the> > instructions> > Yahoo! Groups Links>>> >> >>>>>

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----------------------------

#10265 Jan 1 8:39 PM

Debounce in software? I got some reading to do here.

> bill



One simple way to do debounce in software is to use a timer interrupt to

read the port every 20ms or so. Save the port value in RAM, then have your

software interpret that.



Harold

-- The ideal design has zero parts.



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opportunities available!



----------------------------

#10266 Jan 2 3:00 AM

Easiest de-bounce for switches is not to read them too fast, IE only read them every half a second, as most humans press for more than that etc, very 'cheap' and simple but not a good way, and useless if you need to see exactly when something was pressed, ie a limit/level switch, but for a keypad for selecting a function, more than adequate.


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