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Thread
2005-08-02 by Farzlina Ab.Hadi
2005-08-02 by wbounce
2005-08-03 by Farzlina Ab.Hadi
2005-08-03 by Dave Hylands
On 8/2/05, Farzlina Ab.Hadi <elin@sapura.po.my> wrote: > I configured the ddrf as input by ddrf = 0. But somehow this will make the > current higher..I have to check other ports that are inputs. Just to check > whether it is only adc related problems or not. When the a port is configured as input, you can write a 1 to PORTF to enable the pullup resistor and a 0 to PORTF to disable the pullup resistor. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/
2005-08-03 by Mansur Mansur
Dear All,
Kindly advise how to use optocoupler 4N25 to isolate microcontroller minimum system to Contactors :
1. Output from Port 0.0 to Optocoupler
2. Ouput from Optocoupler to drive contactor
Questions :
1. What should i do with the base pin of the transistor
2. What is the value of the pull up resistor to drive 12V DC to contactor
Please comment.
Thanks
Mansur
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2005-08-03 by Ralph Hilton
On Wed, 3 Aug 2005 12:31:14 +0800 (CST) you wrote: > >Dear All, > >Kindly advise how to use optocoupler 4N25 to isolate microcontroller minimum system to Contactors : > >1. Output from Port 0.0 to Optocoupler > >2. Ouput from Optocoupler to drive contactor > >Questions : > >1. What should i do with the base pin of the transistor > >2. What is the value of the pull up resistor to drive 12V DC to contactor > >Please comment. > >Thanks > >Mansur How much current does the "contactor" need? -- Ralph Hilton http://www.ralphhilton.org C-Meter: http://www.cmeter.org FZAOINT http://www.fzaoint.net
2005-08-03 by Robert Adsett
At 02:08 PM 8/3/05 +0200, Ralph Hilton wrote: >On Wed, 3 Aug 2005 12:31:14 +0800 (CST) you wrote: > > > > >Dear All, > > > >Kindly advise how to use optocoupler 4N25 to isolate microcontroller > minimum system to Contactors : > > > >1. Output from Port 0.0 to Optocoupler > > > >2. Ouput from Optocoupler to drive contactor > > > >Questions : > > > >1. What should i do with the base pin of the transistor > > > >2. What is the value of the pull up resistor to drive 12V DC to contactor > > > >Please comment. > > > >Thanks > > > >Mansur > >How much current does the "contactor" need? Indeed, the devices I refer to as contactors usually draw from 800ma to over 3A to pull in the tips. Well over the rating of most optocouplers. A simple reed relay on the other hand... Robert " 'Freedom' has no meaning of itself. There are always restrictions, be they legal, genetic, or physical. If you don't believe me, try to chew a radio signal. " -- Kelvin Throop, III http://www.aeolusdevelopment.com/
2005-08-03 by Bruce Parham
If low power in needed, all i/o pins need to be in valid high or low states. A floating input that has drifted to some intermediate level can cause the input buffer to draw more current than it would with a valid input. The simplest way to handle this, with an avr, is to set all unused (unconnected) i/o pins to outputs. This forces the pin into a valid level and the input buffer will not draw excessive current. Some older avr parts have a few input only pins. The only way to insure that thay have valid levels is to tie them high or low. Bruce Farzlina Ab.Hadi wrote:
> I configured the ddrf as input by ddrf = 0. But somehow this will make > the current higher..I have to check other ports that are inputs. Just > to check whether it is only adc related problems or not. > thanks! > -------Original Message------- > > From: wbounce <mailto:wbounce@safeplace.net> > Date: 08/03/05 08:01:15 > To: AVR-Chat@yahoogroups.com <mailto:AVR-Chat@yahoogroups.com> > Subject: RE: [AVR-Chat] input port > > ddrf set to 1 makes the port\pins output and enables the pull up > resistor which is why the current is high > -----Original Message----- > From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On > Behalf Of Farzlina Ab.Hadi > Sent: Tuesday, August 02, 2005 5:40 AM > To: AVR-Chat@yahoogroups.com > Subject: [AVR-Chat] input port > > hi, do we actually need to specify the ddr of the port if it to act as > input?. I am working on the ADC of mega128. the adc is working fine but > there's a small issue on the current. I noticed that if I include in the > source code the instruction to set ddrf as input, the current will be > high. but if i remark the instruction, the current will be low. Is there > any connection? > > thank you for any reply. > >
2005-08-03 by Jeffrey Engel
AVRFreaks.net seems to be back up. Jeff Engel Happiness is - positive intake manifold pressure. ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs
2005-08-03 by Ralph Hilton
On Wed, 03 Aug 2005 11:10:23 -0400 you wrote: >At 02:08 PM 8/3/05 +0200, Ralph Hilton wrote: >>On Wed, 3 Aug 2005 12:31:14 +0800 (CST) you wrote: >> >> > >> >Dear All, >> > >> >Kindly advise how to use optocoupler 4N25 to isolate microcontroller >> minimum system to Contactors : >> > >> >1. Output from Port 0.0 to Optocoupler >> > >> >2. Ouput from Optocoupler to drive contactor >> > >> >Questions : >> > >> >1. What should i do with the base pin of the transistor >> > >> >2. What is the value of the pull up resistor to drive 12V DC to contactor >> > >> >Please comment. >> > >> >Thanks >> > >> >Mansur >> >>How much current does the "contactor" need? > >Indeed, the devices I refer to as contactors usually draw from 800ma to >over 3A to pull in the tips. Well over the rating of most optocouplers. A >simple reed relay on the other hand... ok, it is good when you want a meaningful answer to give as much data as possible. How about using a logic level MOSFET? -- Ralph Hilton http://www.ralphhilton.org C-Meter: http://www.cmeter.org FZAOINT http://www.fzaoint.net
2005-08-03 by Robert Adsett
At 09:23 PM 8/3/05 +0200, Ralph Hilton wrote: >On Wed, 03 Aug 2005 11:10:23 -0400 you wrote: > > >At 02:08 PM 8/3/05 +0200, Ralph Hilton wrote: > >>On Wed, 3 Aug 2005 12:31:14 +0800 (CST) you wrote: > >> > >> > > >> >Dear All, > >> > > >> > > >> >Thanks > >> > > >> >Mansur > >> > >>How much current does the "contactor" need? > > > >Indeed, the devices I refer to as contactors usually draw from 800ma to > >over 3A to pull in the tips. Well over the rating of most optocouplers. A > >simple reed relay on the other hand... > >ok, it is good when you want a meaningful answer to give as much data as >possible. > >How about using a logic level MOSFET? Ralph, I think you've confused me with the original poster :) Robert " 'Freedom' has no meaning of itself. There are always restrictions, be they legal, genetic, or physical. If you don't believe me, try to chew a radio signal. " -- Kelvin Throop, III http://www.aeolusdevelopment.com/
2005-08-05 by Mansur Mansur
At 09:23 PM 8/3/05 +0200, Ralph Hilton wrote:
>On Wed, 03 Aug 2005 11:10:23 -0400 you wrote:
>
> >At 02:08 PM 8/3/05 +0200, Ralph Hilton wrote:
> >>On Wed, 3 Aug 2005 12:31:14 +0800 (CST) you wrote:
> >>
> >> >
> >> >Dear All,
> >> >
> >> >
> >> >Thanks
> >> >
> >> >Mansur
> >>
> >>How much current does the "contactor" need?
> >
> >Indeed, the devices I refer to as contactors usually draw from 800ma to
> >over 3A to pull in the tips. Well over the rating of most optocouplers. A
> >simple reed relay on the other hand...
>
>ok, it is good when you want a meaningful answer to give as much data as
>possible.
>
>How about using a logic level MOSFET?
Ralph, I think you've confused me with the original poster :)
Robert
" 'Freedom' has no meaning of itself. There are always restrictions, be
they legal, genetic, or physical. If you don't believe me, try to chew a
radio signal. " -- Kelvin Throop, III
http://www.aeolusdevelopment.com/
Send instant messages to your online friends http://asia.messenger.yahoo.com