Post by thread:[PIC]: IR line detection & Obstacle detection

PROJECT: Infared line detection circuit DESCRIPTION: Ability to correctly identify a significant variance in contrast by sampling at least 6-8 phototransistors while emitting infared light. PROBLEM: Is there some way (using a flip-flop, or otherwise) to only use 2-3 pins to sample all 8 inputs? I'm currently using a 16F84A to do this, run some servos, an LCD, etc (yes, a "robot"). The line detection routines I've seen on the net use a 1-1 sensor to pin configuration... There just HAS to be a better way... :) OTHER USES: Obstacle detection. I've heard of a similar circuit altered slightly to provide obstacle detection up to 1m or so. Modification was something along the lines of sending a modulated pulse and "listening" for that specific pulse, and computing the delay. Has anybody heard of this? Any ideas, code, resources, etc. for either of these would be greatly appreciated... P.S. I'm not necessarily looking for the solution, just a pointer in the right direction on the best way of doing either or both of these. Thanks. While I'm at it, where is the best place to pic up some ultrasonic stuff for obstacle detection (might as well do both, this is a learning experience, right?) -- Rob __________________________________________________ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo.com/ -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 How 'bot the 74HC148 8-to-3 Priority Encoder? http://www.fairchildsemi.com/pf/MM/MM74HC148.html Alternatively, maybe a shift register? Like the 74HC165? Clock, data, reset... - -Randy Glenn This coming from the guy with a system tray 7 icons wide... by 2 tall... ================================================= Randy_Glenn-at-tvo.org - PICxpert-at-picxpert.com PICxpert-at-yahoo.com - PICxpert-at-home.com http://www.picxpert.com/ ================================================= - {Original Message removed}

Rob wrote: >PROJECT: > Infared line detection circuit > >DESCRIPTION: > Ability to correctly identify a significant variance in contrast by >sampling at least 6-8 phototransistors while emitting infared light. > >PROBLEM: > Is there some way (using a flip-flop, or otherwise) to only use 2-3 >pins to sample all 8 inputs? I'm currently using a 16F84A to do this, >run some servos, an LCD, etc (yes, a "robot"). The line detection >routines I've seen on the net use a 1-1 sensor to pin configuration... >There just HAS to be a better way... :) You could use a shift register to pull in 8 lines quickly. That will use only 3 lines I think. (load, clock, data) It also has the advantage of being expandable to more inputs without using any more I/O pins. This is the way to go if digital inputs are what you need. If you want to sample analog voltages then you need a MUX (CD4051) but that will need 3 lines to select 1 of 8 inputs and one line for the selected input itself. Hope this gives you some ideas. {Quote hidden}>OTHER USES: > Obstacle detection. I've heard of a similar circuit altered slightly >to provide obstacle detection up to 1m or so. Modification was >something along the lines of sending a modulated pulse and "listening" >for that specific pulse, and computing the delay. Has anybody heard of >this? Any ideas, code, resources, etc. for either of these would be >greatly appreciated... > >P.S. I'm not necessarily looking for the solution, just a pointer in >the right direction on the best way of doing either or both of these. >Thanks. > >While I'm at it, where is the best place to pic up some ultrasonic >stuff for obstacle detection (might as well do both, this is a learning >experience, right?) Check piclist.com - there should be something in there about this... -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu

> You could use a shift register to pull in 8 lines quickly. That will use > only 3 lines I think. (load, clock, data) It also has the advantage of > being expandable to more inputs without using any more I/O pins. > This is the way to go if digital inputs are what you need. If you want > to sample analog voltages then you need a MUX (CD4051) but that > will need 3 lines to select 1 of 8 inputs and one line for the selected > input itself. Hope this gives you some ideas. Or two lines to output mux address to a shift register (Clock, Data) and 1 analog input to read the mux. Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

>PROBLEM: > Is there some way (using a flip-flop, or otherwise) to only use 2-3 >pins to sample all 8 inputs? I'm currently using a 16F84A to do this, >run some servos, an LCD, etc (yes, a "robot"). The line detection >routines I've seen on the net use a 1-1 sensor to pin configuration... >There just HAS to be a better way... :) I believe you could use a 3-wire parallel in-serial out decoder (74HC138 or similar) to sample 8 inputs with 3 pins. --Andrew _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

He, I'am working on a simular project. And we decided that we should only use ultrasonic for the detection of obstacles and use IR for communication. This is becose we think you can't measure the delay on the speed of time. But maybe we are wrong?... This is for us also a learning project (And we have still a lot to learn) so every information is welcom. Best regards, Djurre {Quote hidden}> > PROJECT: > Infared line detection circuit > > DESCRIPTION: > Ability to correctly identify a significant variance in contrast by > sampling at least 6-8 phototransistors while emitting infared light. > > PROBLEM: > Is there some way (using a flip-flop, or otherwise) to only use 2-3 > pins to sample all 8 inputs? I'm currently using a 16F84A to do this, > run some servos, an LCD, etc (yes, a "robot"). The line detection > routines I've seen on the net use a 1-1 sensor to pin configuration... > There just HAS to be a better way... :) > > OTHER USES: > Obstacle detection. I've heard of a similar circuit altered slightly > to provide obstacle detection up to 1m or so. Modification was > something along the lines of sending a modulated pulse and "listening" > for that specific pulse, and computing the delay. Has anybody heard of > this? Any ideas, code, resources, etc. for either of these would be > greatly appreciated... > > P.S. I'm not necessarily looking for the solution, just a pointer in > the right direction on the best way of doing either or both of these. > Thanks. > > While I'm at it, where is the best place to pic up some ultrasonic > stuff for obstacle detection (might as well do both, this is a learning > experience, right?) > > -- Rob > > > __________________________________________________ > Do You Yahoo!? > Get personalized email addresses from Yahoo! Mail - only $35 > a year! http://personal.mail.yahoo.com/ > > -- > http://www.piclist.com hint: To leave the PICList > .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu Find the best deals on the web at AltaVista Shopping! http://www.shopping.altavista.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Drew Vassallo wrote: > > >PROBLEM: > > Is there some way (using a flip-flop, or otherwise) to only use 2-3 > >pins to sample all 8 inputs? I'm currently using a 16F84A to do this, > >run some servos, an LCD, etc (yes, a "robot"). The line detection > >routines I've seen on the net use a 1-1 sensor to pin configuration... > >There just HAS to be a better way... :) > > I believe you could use a 3-wire parallel in-serial out decoder (74HC138 or > similar) to sample 8 inputs with 3 pins. Have you done a web search for "line following robot", there are a lot of club sites that have info on building these. Generally you only need two sensors, not eight, and you sense them as analog to give a linear position reference. Maybe this method would suit your needs? :o) -Roman -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads