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Discussion Groups | Piclist | Re: External interrupts
A discussion group for the PICMicro microcontroller. Also called the Microchip PIC, this list is dedicated to the use and abuse of this fine, simple, microcontroller. Close to topic posts are welcome, ie. general electronics.
External interrupts - "Kenneth (K) Macrae" - Sep 29 9:22:25 2008
Hi
I'm using a PIC16F84a to control a UV light box.
I've got an external interrupt which is connected to the door, which acts as
an interlock. If the UV light is on, and the door is opened, the light will
switch off. The light will also not switch on while the door is open.
The problems is:
When the UV light (fluorescent type) switches on, it seems to trigger the
external interrupt, but other interrupts are do not appear to be triggered
(RB4 - 7, interrupt on change)
Is it "magnetic " interference (from what i read) from the ballast? Or am I
missing something really basic? What filters would i need to possible use?
Thanks
Kenneth
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
I'm using a PIC16F84a to control a UV light box.
I've got an external interrupt which is connected to the door, which acts as
an interlock. If the UV light is on, and the door is opened, the light will
switch off. The light will also not switch on while the door is open.
The problems is:
When the UV light (fluorescent type) switches on, it seems to trigger the
external interrupt, but other interrupts are do not appear to be triggered
(RB4 - 7, interrupt on change)
Is it "magnetic " interference (from what i read) from the ballast? Or am I
missing something really basic? What filters would i need to possible use?
Thanks
Kenneth
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
Re: External interrupts - Eirik Karlsen - Sep 29 10:32:02 2008
Try grounding the pin at the chip and see if it is affected when the light switches on...
if not then it sounds like a EMI problem.
Try a 100nF - 1uF cap from pin to gnd, slose to the chip. For the safety of the chip you may want to put 330R in series with
the pin to protect it in case of SW bug or whatever that might output pulses to the pin.
"Kenneth (K) Macrae" wrote:
> Hi
>
> I'm using a PIC16F84a to control a UV light box.
>
> I've got an external interrupt which is connected to the door, which acts as an interlock. If the UV light is on, and the door is opened, the light will switch off. The light will also not switch on
> while the door is open.
>
> The problems is:
>
> When the UV light (fluorescent type) switches on, it seems to trigger the external interrupt, but other interrupts are do not appear to be triggered (RB4 - 7, interrupt on change)
>
> Is it "magnetic " interference (from what i read) from the ballast? Or am I missing something really basic? What filters would i need to possible use?
> Thanks
>
> Kenneth
>
--
*******************************************
VISIT MY HOME PAGE:
LAST UPDATED: 23/08/2003
*******************************************
Regards
Eirik Karlsen
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
Try a 100nF - 1uF cap from pin to gnd, slose to the chip. For the safety of the chip you may want to put 330R in series with
the pin to protect it in case of SW bug or whatever that might output pulses to the pin.
"Kenneth (K) Macrae" wrote:
> Hi
>
> I'm using a PIC16F84a to control a UV light box.
>
> I've got an external interrupt which is connected to the door, which acts as an interlock. If the UV light is on, and the door is opened, the light will switch off. The light will also not switch on
> while the door is open.
>
> The problems is:
>
> When the UV light (fluorescent type) switches on, it seems to trigger the external interrupt, but other interrupts are do not appear to be triggered (RB4 - 7, interrupt on change)
>
> Is it "magnetic " interference (from what i read) from the ballast? Or am I missing something really basic? What filters would i need to possible use?
> Thanks
>
> Kenneth
>
--
*******************************************
VISIT MY HOME PAGE:
LAST UPDATED: 23/08/2003
*******************************************
Regards
Eirik Karlsen
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
Re: External interrupts - Dennis Clark - Sep 29 12:06:49 2008
Without seeing your circuit it's hard to say. Electronic ballasts tend to
spike a really high in-rush current on start up so that might be spiking
your power rail. But we're guessing without more information.
DLC
> Hi
>
> I'm using a PIC16F84a to control a UV light box.
>
> I've got an external interrupt which is connected to the door, which acts
> as
> an interlock. If the UV light is on, and the door is opened, the light
> will
> switch off. The light will also not switch on while the door is open.
>
> The problems is:
>
> When the UV light (fluorescent type) switches on, it seems to trigger the
> external interrupt, but other interrupts are do not appear to be triggered
> (RB4 - 7, interrupt on change)
>
> Is it "magnetic " interference (from what i read) from the ballast? Or am
> I
> missing something really basic? What filters would i need to possible
> use?
> Thanks
>
> Kenneth
>
--
Dennis Clark
TTT Enterprises
------------------------------------
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spike a really high in-rush current on start up so that might be spiking
your power rail. But we're guessing without more information.
DLC
> Hi
>
> I'm using a PIC16F84a to control a UV light box.
>
> I've got an external interrupt which is connected to the door, which acts
> as
> an interlock. If the UV light is on, and the door is opened, the light
> will
> switch off. The light will also not switch on while the door is open.
>
> The problems is:
>
> When the UV light (fluorescent type) switches on, it seems to trigger the
> external interrupt, but other interrupts are do not appear to be triggered
> (RB4 - 7, interrupt on change)
>
> Is it "magnetic " interference (from what i read) from the ballast? Or am
> I
> missing something really basic? What filters would i need to possible
> use?
> Thanks
>
> Kenneth
>
--
Dennis Clark
TTT Enterprises
------------------------------------
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Re: External interrupts - "John J. McDonough, WB8RCR" - Sep 29 13:17:18 2008
----- Original Message -----
From: "Dennis Clark"
To:
Sent: Monday, September 29, 2008 12:06 PM
Subject: Re: [piclist] External interrupts
> Without seeing your circuit it's hard to say.
And code as well. There are plenty of ways to THINK you aren't getting an
interrupt.
72/73 de WB8RCR http://www.qsl.net/wb8rcr
didileydadidah QRP-L #1446 Code Warriors #35
------------------------------------
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Re: External interrupts - "Kenneth (K) Macrae" - Sep 29 14:08:48 2008
I've solved it.
The control box was right on top of the light (separated by a layer of MDF)
I have moved the control box off the UV box, and it works properly now. It
seems that having the control circuit so close to the ballast really was a
problem.
Kenneth
2008/9/29 John J. McDonough, WB8RCR
>
> ----- Original Message -----
> From: "Dennis Clark">
> To:>
> Sent: Monday, September 29, 2008 12:06 PM
> Subject: Re: [piclist] External interrupts
>
> > Without seeing your circuit it's hard to say.
>
> And code as well. There are plenty of ways to THINK you aren't getting an
> interrupt.
>
> 72/73 de WB8RCR http://www.qsl.net/wb8rcr
> didileydadidah QRP-L #1446 Code Warriors #35
>
>
>
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
The control box was right on top of the light (separated by a layer of MDF)
I have moved the control box off the UV box, and it works properly now. It
seems that having the control circuit so close to the ballast really was a
problem.
Kenneth
2008/9/29 John J. McDonough, WB8RCR
>
> ----- Original Message -----
> From: "Dennis Clark"
> To:
> Sent: Monday, September 29, 2008 12:06 PM
> Subject: Re: [piclist] External interrupts
>
> > Without seeing your circuit it's hard to say.
>
> And code as well. There are plenty of ways to THINK you aren't getting an
> interrupt.
>
> 72/73 de WB8RCR http://www.qsl.net/wb8rcr
> didileydadidah QRP-L #1446 Code Warriors #35
>
>
>
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