Post by thread:[PIC:]Need solid +5VDC level for input to PIC

Hi all, I am working with an optical encoder which outputs a voltage between +0.35VDC and +1VDC. What is the easiest low component count method for getting a clean 0V to 5V pulse from this to use as an input to the PIC? Thanks. Regards, Stephen D. Barnes -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

From: "Stephen D. Barnes" <.....stephendbarnesKILLspam@spam@HOTPOP.COM> > Hi all, > I am working with an optical encoder which outputs a voltage > between +0.35VDC and +1VDC. What is the easiest low > component count method for getting a clean 0V to 5V pulse > from this to use as an input to the PIC? > Thanks. > > Regards, > Stephen D. Barnes It seems like a comparator would work well. Just put 0.7 V or so at one input, and the encoder's output at the other input. Daniel Imfeld -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

The first way that jumps to mind is the old-fashioned transistor switch. It only needs three parts, is available off the shelf, easy to assemble, and its cheap. You said it outputs a voltage, so you could probably use a mosfet instead of a bipolar. Or a comparator would probably work great, just set the - input to your trigger voltage and put the encoder on the +. : Hi all, : I am working with an optical encoder which outputs a voltage : between +0.35VDC and +1VDC. What is the easiest low : component count method for getting a clean 0V to 5V pulse : from this to use as an input to the PIC? : Thanks. : : Regards, : Stephen D. Barnes -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

> The first way that jumps to mind is the old-fashioned transistor switch. It > only needs three parts, is available off the shelf, easy to assemble, and > its cheap. You said it outputs a voltage, so you could probably use a > mosfet instead of a bipolar. Or a comparator would probably work great, > just set the - input to your trigger voltage and put the encoder on the +. > > > > : Hi all, > : I am working with an optical encoder which outputs a voltage > : between +0.35VDC and +1VDC. What is the easiest low > : component count method for getting a clean 0V to 5V pulse > : from this to use as an input to the PIC? > : Thanks. > : > : Regards, > : Stephen D. Barnes Would a 555 timer in monostable mode work? I do have many of these hanging around? Regards, Stephen D. Barnes -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

> I am working with an optical encoder which outputs a voltage > between +0.35VDC and +1VDC. What is the easiest low > component count method for getting a clean 0V to 5V pulse > from this to use as an input to the PIC? If those voltages are reliable levels then a transistor will work well with 3 resistors. If they aren't reliable then a bit of design will still produce the goods. Ask with more details if this is the case. A 555 as suggested MAY work but needs design. TRANSISTOR. DESIGN Cheap. Easy. Compact. Learn something. Works. NPN small signal. Just about anything. (2N2222 or whatever) R1 Input resistor 10k to 100K from input signal to base. R2 Pulldown / leakage shunt 100k to 1 megohm base to ground. R3 Collector resistor 10k to 100k collector to Vdd. PIC pin to Vdd. R2 can perhaps be omitted but its good to have it. Cheap. Simple. Works if voltages are as stated. R1 larger makes less load on signal R2 at least 10 x R1 (more OK) R3 could be 1M probably but 100K OK. If this signal is very high speed things will get more complex. The above should probably work at eg 10 kbps without a thought. Maybe at 100 kbps Almost certainly not at 1 Mbps Russell McMahon -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

{Quote hidden}> > I am working with an optical encoder which outputs a voltage > > between +0.35VDC and +1VDC. What is the easiest low > > component count method for getting a clean 0V to 5V pulse > > from this to use as an input to the PIC? > > If those voltages are reliable levels then a transistor will work well with > 3 resistors. > > If they aren't reliable then a bit of design will still produce the goods. > Ask with more details if this is the case. > > A 555 as suggested MAY work but needs design. > > TRANSISTOR. DESIGN > > Cheap. Easy. Compact. Learn something. Works. > > NPN small signal. Just about anything. (2N2222 or whatever) > > R1 Input resistor 10k to 100K from input signal to base. > R2 Pulldown / leakage shunt 100k to 1 megohm base to ground. > R3 Collector resistor 10k to 100k collector to Vdd. > PIC pin to Vdd. > > R2 can perhaps be omitted but its good to have it. > > Cheap. Simple. Works if voltages are as stated. > > R1 larger makes less load on signal > R2 at least 10 x R1 (more OK) > R3 could be 1M probably but 100K OK. > > If this signal is very high speed things will get more complex. The above > should probably work at eg 10 kbps without a thought. > Maybe at 100 kbps > Almost certainly not at 1 Mbps > > > > Russell McMahon The speed of the encoder will never reach those speeds. This sound like it will do the trick and I do have a handfull of 2SC536 NPN transistors (TO-92)! Thanks to everyone for their input....now on to the breadboarding! Regards, Stephen D. Barnes -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email @spam@listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> Hi all, > I am working with an optical encoder which outputs a voltage > between +0.35VDC and +1VDC. What is the easiest low > component count method for getting a clean 0V to 5V pulse > from this to use as an input to the PIC? > Thanks. Easiest would be an NPN transistor, two resistors and the transistor is all you'd need. TTYL -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu

> It seems like a comparator would work well. Just put 0.7 V or so at > one input,and the encoder's output at the other input. A comparator was the first thing I thought of too. If you use a PIC that already has a comparator you won't need any external components. Shahid -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

Stephen D. Barnes wrote: > I am working with an optical encoder which outputs a voltage > between +0.35VDC and +1VDC. What is the easiest low > component count method for getting a clean 0V to 5V pulse > from this to use as an input to the PIC? An opamp and a few resistors can do this. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestspamBeGonemitvma.mit.edu

>> I am working with an optical encoder which outputs a voltage >> between +0.35VDC and +1VDC. What is the easiest low >> component count method for getting a clean 0V to 5V pulse >> from this to use as an input to the PIC? > > An opamp and a few resistors can do this. After seeing other replies I realized the OP wanted to compare the signal to a threshold, not present it to an A/D input. Sorry. The best solution for that is to use a PIC with a comparator. That failing, the next easiest circuit depends on the impedence of the input signal and speed requirement. A single transistor and resistor could be good enough if the PIC input has an internal pullup. 350mV to 1V is a very convenient range for detecting with a silicon transistor, which would has a threshold of around 700mV. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestEraseMEspam_OUTmitvma.mit.edu

Hello everyone, First, I would like to thank all who have replied to my posts concerning this thread and the one about the MS mouse schematics. I have been trying to hack a mouse to use as wheel encoders on a hobby robot. The voltage levels from the detectors in the mouse (0.35 to 1.00 vdc) had me very confused. I have just found out that the MS mouse is pulsing the emitters at 38 or 40 KHz (not sure which 'cause I do not have a scope handy at the moment). I connect the detector output to the timer1 input configured for external clock on a 18F4320. Connected portB to led's and watched the count as I rotate the toothed wheel. If I stop the wheel so that IR passes to the detector, BOOM, it it increments timer1 with no wheel rotation. Block the detector and the increment stops! I'll have to remove the Zilog chip from the mouse and connect the IR emitters for continuous operation. I was actually reading a high pulse rate with a meter set to DC volts and was reading idle current/voltage and then approx. 40KHz pulses which averaged out to be about 1 VDC! Learned a valuable lesson from this one. Again, thanks for all the help folks. Regards, Stephen D. Barnes -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

>> I am working with an optical encoder which outputs a voltage >> between +0.35VDC and +1VDC. What is the easiest low >> component count method for getting a clean 0V to 5V pulse >> from this to use as an input to the PIC? >> Thanks. >> >> Regards, >> Stephen D. Barnes > >It seems like a comparator would work well. Just put 0.7 V or so at one >input, and the encoder's output at the other input. Use a PIC with a comparator input, and then you do not need any extra components? Most of the new ones have comparators. -- 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