Post by thread:[PIC]: Monitoring switch(s) state

Hi All Did anyone come across a circuit that can monitor the state of some switches? The general idea is to monitor the state of any switch (high/low) and measure the elapsed time that the switch is on or off. any circuit or idea will be most appreciate. Thanks Tal -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Tal wrote : > Did anyone come across a circuit that can monitor the state of some > switches? > The general idea is to monitor the state of any switch (high/low) and > measure the elapsed time that the switch is on or off. > any circuit or idea will be most appreciate. > > Thanks I must be missing something here... A circuit to measure elapsed time ? Using a PIC seams in line with the general topic of this maillist :-) A pin with the internal pullup enabled maybe ? Is this an old thread ? Jan-Erik. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Jan-Erik Forget it. I will look harder on the 'net. Tal -----Original Message----- From: pic microcontroller discussion list [spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU]On Behalf Of Jan-Erik Soderholm XA (TN/PAC) Sent: Tuesday, October 21, 2003 12:24 AM To: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU Subject: Re: [PIC]: Monitoring switch(s) state Tal wrote : > Did anyone come across a circuit that can monitor the state of some > switches? > The general idea is to monitor the state of any switch (high/low) and > measure the elapsed time that the switch is on or off. > any circuit or idea will be most appreciate. > > Thanks I must be missing something here... A circuit to measure elapsed time ? Using a PIC seams in line with the general topic of this maillist :-) A pin with the internal pullup enabled maybe ? Is this an old thread ? Jan-Erik. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Sounds more like a homework assignment. Not enough detail. Monitor for days, hours, minutes, miliseconds? R "Jan-Erik Soderholm XA (TN/PAC)" wrote: {Quote hidden}> > Tal wrote : > > Did anyone come across a circuit that can monitor the state of some > > switches? > > The general idea is to monitor the state of any switch (high/low) and > > measure the elapsed time that the switch is on or off. > > any circuit or idea will be most appreciate. > > > > Thanks > > I must be missing something here... > > A circuit to measure elapsed time ? > Using a PIC seams in line with the general topic of this maillist :-) > A pin with the internal pullup enabled maybe ? > > Is this an old thread ? > > Jan-Erik. > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

ummmm....easy use TMR0 as an interupt for incrementing time check flag for status of input bit inside ISR increment register(s) if bit is on(off) _________________________________________________________________ Send instant messages to anyone on your contact list with MSN Messenger 6.0. Try it now FREE! http://msnmessenger-download.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Robert and others First, I admit that I have no idea how to write a code for pic's. this is the reason I ask for help. What I am looking for is very simple, a circuit that start when a switch is pressed for a brief time I call it "start". this switch is ignored if pressed again until "reset" switch is activate. another switch is activating a led while is pressed alternately this I call it "running". the "reset" switch function in this way: if the switch is pressed for lets say 10 seconds (no less) then a buzzer is activate. any time less then 10 sec will keep the circuit running (led is blinking while "running" is alternately pressed) and "start" switch is ignored. if "reset" is activated more than 10 sec then "start" switch can start the circuit all over again, and so on. like a loop. hope I explain my self coherently. I'll appreciate any help! Tal {Original Message removed}

> What I am looking for is very simple, a circuit that start when a switch is > pressed for a brief time I call it "start" Detect Start switch (I presume a pushbutton) Assuming switches connected to Port A and active high #define start_sw porta,0 #define reset_sw porta,1 In your code test_sw btfss start_sw ;wait for a "1" to appear on porta,0 goto test_sw ;else loop while "0" > this switch is ignored if pressed again until "reset" switch is activate So don't test start_sw again until reset ============================ > another switch is activating a led while is pressed alternately this I call > it "running" Don't quite understand that function. ============================ > the "reset" switch function in this way: if the switch is pressed for lets > say 10 seconds (no less) then a buzzer is activated reset btfss reset_sw ;wait for a "1" to appear on porta,1 goto reset ;else loop while "0" What you could do hear is start a timer interrupt that can be used to measure how long reset_sw is depressed. The settings will depend on which PIC and how fast For example, an F6228 running at 3.2768MHz Timer1 free-running will generate 12.5 interrupts/second = 125 in 10 seconds Enable the interrupts on the first detection of reset_sw being pushed and each time there's an interrupt, test for both reset_sw depressed and interrupt counter = 125. If reset_sw is not depressed then 0 the counter. If counter = 125 then do the reset. Having reset_sw on portb,0 or other external interrupt source might make it easier to detect a press, depending on your code Simplistic but that's a way it could be done -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Jinx Thanks it's a start for me! about the "running" switch: the machine have a part that move alternately all the time (forward - backward) so each time the moving part is crossing the middle of it's travel it press a switch (can be a reed relay or something else..) so I want to see by light from a distance that the part is moving and doesn't in hold/stop position. Ex.: monitoring a turning plate that finish each turn by activating the switch/reed relay etc... Tal {Original Message removed}

Tal wrote: > ... so I want to see by light from a distance that the part is moving and doesn't in hold/stop position... Tal, I don't know the details, but, Would it not be better to have some kind of lamp or alarm that shows that the part is *NOT* moving ? Like a siren or a rotating flashing light. What is the most likely status, "moving" or "not moving" ? Jan-Erik. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> about the "running" switch: the machine have a part that > move alternately all the time (forward - backward) so each > time the moving part is crossing the middle of it's travel it > press a switch OK, that's something that an external interrupt pin would be useful for. When the switch is activated by this moving piece of machinery it can alert the PIC a couple of ways. One is to use the INT flag to store this event. Whether or not the external interrupt is enabled, INTF will be set by a switch transition until your code resets it. You could look for this flag as part of the Timer1 ISR. If it's set, turn a LED on for a Timer1 interrupt period. An 80ms flash is quite noticeable, but you could keep the LED on for the duration of a counter driven by Timer1 IRQs #define led porta,2 ISR ----- bcf led ;turn LED off by default btfss intcon,intf ;test for external event goto process_timer1_irq ;no, carry on with no LED lit bcf intcon,intf ;yes, clear flag bsf led ;light LED bcf tmr1if ;clear Timer1 flag process_timer1_irq ;continue retfie The other way would be to have Timer0 as a counter and set it to 0xFF. A pulse coming into RA4 will cause Timer0 to rollover to 0x00 and set T0IF, which you can check for -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

> useful for. When the switch is activated by this moving piece > of machinery it can alert the PIC a couple of ways. Oh, another way I meant to mention was using an RC to store the event. That way you could use a general purpose I/O pin Set the pin as an input, C to ground and R to 5V via the switch. When the switch closes the C will charge up and record the closure. You can read this when your code has time. Set the pin to an output and "0" to discharge the cap. It shouldn't need a very big cap to do this, maybe a few nF. It depends on how long the switch is closed for. Discharging C through a resistor, a couple of hundred ohms, would be safe R to 5V through switch I pin --- R ---- C to 0V -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Slight correction to previous code snippet, sorry, put flag clear before the label bcf led ;turn LED off by default btfss intcon,intf ;test for external event goto process_timer1_irq ;no, carry on with no LED lit bcf intcon,intf ;yes, clear flag bsf led ;light LED process_timer1_irq ;continue bcf tmr1if ;clear Timer1 flag -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body