perisitance of vision

hello,

I am having a play around with 'perisitance of vision project (row of LED's spining around making words). I have seen a few posts that use all the pins on on 'axe' to turn on individual LED's.

I have tried a different tack on this by useing an 08m and a 74HC164 (ser/par shift reg) chip.

The theroy is working but the programing is weak. Anyone have any good ideas to effectivly run this?

The pin driven project had just had ....

example for 'A'

letter_a:
pause 2
let pins = %00111111
pause 2
let pins = %01001000
pause 4
let pins = %00111111
pause 2
let pins = %00000000
return

But my project requires a clock pulse etc between each signal.

Cheers,

Jason

<A href='http://www.rev-ed.co.uk/picaxe/forum/Topic.asp?whichpage=1&amp;pagesize=15&amp;forum_title=No+new+posts+please%21+8&amp;topic_title=Persistence%2Bof%2BVision%2B%2528POV%2529%2Bcircuit%2B%253F&amp;forum_id=14&amp;topic_id=2048' Target=_Blank>External Web Link</a>

A check in the forum will give several posts on this subject - which as far as i know has yet to be cracked!

search for POV - try the link above for a start.

I had the feeling Silicon chip may have done
one of these.
I did a search,, but came up empty.

I found this though - <A href='http://www.giganticsigns.com.au/led-electronics/spacewriter.htm ' Target=_Blank>External Web Link</a>
If you look half way down the page the letters
A to Z are there, if you blow them up you can
just make out what components make up each letter,,~ ;o)
You need 7 LEDs in a row and 5 timing sequences for
each letter by the looks.

You'll need some code like the SHIFTOUT examples described in the PICAXE Manual 2 to use the 164 shift register.

There are three potential disadvantages to using a shift register over a 'pins=' assignment ...

The 'pins=' sets all LED's in one go and takes around 250uS to operate.

If the shift register drives the LED's and it isn't a shift-and-buffered-latch type ( I don't think the 164 is ), as each bit is clocked into it, the LED display will slide across the LED's and you'll see a blur of dots rather than the final LED display after all bits have been clocked out.

Bit-banging the data into the shift register will take a lot longer, at least 16 times longer and probably more. This limits the maximum rate at which the LED bar can be changed. If the POV device has an arc of travel which takes 1 second to complete, 'pins=' potentially allows for a display of up to 4000 pixels wide. A shift register would limit that to 250 pixels and likely less.

All 'pins=' statements can be programmed as a sequential list which maximises operational speed. Bit-banging will really require a subroutine to do that which has to be called for every new LED display, which introduces the limit of 256 GOSUB's and adds extra time taken for processing, which again reduces the display update rate.

Edited by - hippy on 2/4/2006 11:08:55 AM

There is an easily built &quot;spinning&quot; POV display that has schematic, algorithm, and Hex file on the site. Uses pic12f629 and not much else. Built it for the kids and they loved it. Easy to change the messages and could (maybe) be converted to 08M use. Try this link---- http://www.josepino.com/11/index.html
Many picts and clear instructions.

Hello,

Some information I can add ...

POV is an interesting subject, maybe if I find time I will do one with my son ...

In many links it is stated that a super-bright lED with a relative large view angle is best.

Maybe the MAX6956 is a good option in combination with a picaxe-18x as it has programmable current drivers for LEDs and the chip allows for much higher total dissipation (as required by a large number of leds) than PICs or regular I/O extension chips. The i2c commands will require more execution time though than the discussed &quot;let pins=&quot; command.

Best Regards,
Jurjen Kranenborg
http://www.kranenborg.org/ee/picaxe

PS: A number of interesting links, to get even more inspired:

http://www.ianpaterson.org/projects/spokepov20050704/index.htm
http://www.ladyada.net/make/minipov2/index.html
http://www.microsyl.com/ - MicroSyl MCU
http://www3.sympatico.ca/surfin.dude/creative/clocks/propclk...blick.html - My Blick Propeller Clock Design
http://www.jobie.com/project3.htm - Project 3 Spinning LED Display
http://hot-streamer.com/hilo90mhz/electronics/prop_clock.htm - Propeller Clock Chester
http://www.everville.de/pages/projects/propclock/index.htm - Propeller Clock
http://home.epix.net/~iracerc/clock.html - Propellor clock, by Otis.
http://homepages.slingshot.co.nz/~shirolla/ - Shirollah's PIC &amp; AVR page
http://www.twyman.org.uk/3D-Display/#apps -3D Scanning LED Display#apps
http://www.mcselec.com/an_128.htm -AN 128, Moving LED messaging Waver with BI-colour LEDS
http://blondini.orcon.net.nz/clock.html - An unusual LED clock
http://www.luberth.com/analog.htm - Analog &amp; Digital propeller Clock
http://www.feertech.com/andy/picclock.html - Andy's Personal Page
http://jstampu.systronix.com/appnotes/fantazein/fantazein_jstamp.htm - App Note Fantazein clock with JStamp
http://www.spicken.de/donald/ - Armins Propeller-Uhr
http://www.eng.bcit.ca/tted/electronics/electronicsprojects.htm - B.C. Electronics Teachers' Resource Site Projects
http://webook.fset.de/20091999PHCHO/PIC1PROG/CLOCK/CLK.htm - Bob Blick's Propeller Clock
http://www.bobtech.home.ro/scheme/microcontrolere/clock/ - BobTech - Scheme Electonnice
http://www.thomas-otterbein.de/pic/index.html - Das PIC Projekt
http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects...iteup.html - Digital Mirror Message Machine
http://www.geocities.com/siliconvalley/campus/9489/propclock.html - Don Zehnder's Analog and Digital Propeller Clock
http://www.geocities.com/siliconvalley/campus/9489/javaclock1.html - Don Zehnder's Java Bob Blick Propeller Clock Page
http://homepages.tu-darmstadt.de/~dpraclik/pic/picprojekte/drehuhr.htm - Drehuhr
http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects...0/winslow/ - EE476 Final Project Page
http://home.t-online.de/home/kurt.schuster/elctron/elfcont.htm - electronic content 01
http://home.t-online.de/home/kurt.schuster/elctron/elfpage.htm - electronic page 01
http://www10.brinkster.com/gezgini/Konular.asp?ad_id=38&amp; - Elektronik Mekani
http://students.vassar.edu/hrgovard/digital/final%20report_engs31.htm - Final Report
http://engineering.dartmouth.edu/~cokino/classes/ES62F00PROJ...ovill.html - Floating Time Mechanical Scanning LED Clock
http://ubob.ponnet.com/concept.html - Ghost Clock
http://www.seattlerobotics.org/encoder/200112/srs.htm - How to Build a Spinning Sign and Other Free-Rotating Active Mechanisms
http://home.student.uu.se/r/rost7041/
http://homepage.ntlworld.com/geoff.crowley/mattweb/propclock/ - MattWeb Projects The Propeller Clock - Main
http://www.cinternet.net/~monty/clock/ - Mechanically Scanned Clock 2
http://pages.sbcglobal.net/ken_staton/electronics/prop_clock...p_clk.html - Mechanically Scanned Clock
http://home.planet.nl/~heuv0283/scan_cl/scan_cl.htm - Mechanically scanned display
http://www.meek.de/www/clock/index.htm - meek.de
http://www.jwardell.com/about/juniorproj/constr.html - Mid-Air Oscillating LED Sign
http://www3.sympatico.ca/surfin.dude/creative/clocks/propclk...blick.html - My Blick Propeller Clock Design
http://www.metricmind.com/clock/clock.htm - PIC clock
http://www.bobblick.com/techref/projects/propclock/propclock...lock2.html - Propclock2
http://pages.sbcglobal.net/ken_staton/electronics/prop_clock..._Clock.htm - Propeller Clock Design
http://www.bobblick.com/techref/projects/propclock/propclock.html - Propeller Clock
http://home.quicknet.nl/qn/prive/m.ursum/propclock.html - Propellor Clock
http://www.rickard.gunee.com/projects/mechscan/dualpic/clock.php - Rickard's electronic projects page - Virtual Clock
http://home.planet.nl/~swets022/ - Swets Hobby Homepage
http://homepage.ntlworld.com/geoff.crowley/mattweb/propclock/ - The Propeller Clock - Main
http://homepage.ntlworld.com/geoff.crowley/mattweb/propclock/files.htm - The Propeller Clock - Project Files
http://www.geocities.com/tjacodesign/propclock/propclock.html - Tjaco's design graveyard
http://www.transistornet.de/viewtopic.php?p=2353&amp;sid=0cb...08b5da6c07 - TransistorNet.de Thema anzeigen - Rotations Laufschrift
http://www.ispf.de/propclock/
http://home.mweb.co.za/gr/grrr/picmicro/clock.html - What is a PIC
http://www.ponnet.com/projects/propeller/index1.0.php
http://www.ponnet.com/projects/propeller/
http://www.wirkungsquantum.net/elektronik/propeller_clock/pr...clock.html
http://www.teknokent.org/pic/pic_uygulamalar/7_ledli_saat/saat.htm - Yeni Sayfa

Edited by - kranenborg on 2/4/2006 8:52:40 PM

kranenborg, looks like you have way, way too
much spare time on your hands.
Come and clean up my garage, please..~ ;o)

Well ...

I must admit that I have not compiled the list myself; it is from a Dutch site on electronics (www.circuitsonline.net). My posting took me less than 10 minutes

I decided to share the info here as well as the POV concept has a certain elegance to me: relatively simple to build (but with an mechanical engineering aspect added), clear constraints and probably a huge impact in the public sphere; a perfect challenge for a picaxe!

Regards,
Jurjen

PS. Michael727: Many interesting things may pop up in a garage, so I would be happy to ... But I just migrated from the Netherlands to Sweden, and to my knowledge I am now even further away from Australia (minus 15 degrees Celsius as I am typing now in Uppsala) ...

Edited by - kranenborg on 2/4/2006 9:04:07 PM

Hi
I Haven't Used a 164 with a picaxe but have used 595's with an 08M.
Here is my output routine.

Set595:
Symbol Latch595 = 0
Symbol Clock595 = 1
Symbol Data595 = 2
Symbol OutByte = B0
Symbol X = B1
Symbol IoBit = Bit7

high Latch595
For X = 1 to 8
Low Data595
If IoBit = 0 then SkipHi
High Data595
SkipHi:
PulsOut Clock595,1
OutByte = OutByte * 2
Next
PulsOut Latch595,1
Return

I've since been building stuff around mcp23017's.
One Very quick line of code to set 8 Bits via i2c &amp; there are 2 ports avail.

Forgot to mention .. but you already know, 08M no i2c.
Also the code above may have typo's as I modified it from the original ...

Edited by - barryp on 2/5/2006 12:04:25 AM

Yeah,

Hippy might be right on the speed thing. Although I have the circuit running now it appears quite quick even though it has no bufferd latches.

But the long term goal is to go tri-colour so might have to pull out the big guns and run each one off a pin.

JK - Not wishing to rain on your parade but the only links in that list that are current are

<A href='http://www.kranenborg.org/ee/picax' Target=_Blank>External Web Link</a>
<A href='http://www.ianpaterson.org/projects/spokepov20050704/index.htm' Target=_Blank>External Web Link</a>
<A href='http://www.ladyada.net/make/minipov2/index.html' Target=_Blank>External Web Link</a>
<A href='http://www.twyman.org.uk/3D-Display/#apps -3D Scanning LED Display#apps' Target=_Blank>External Web Link</a>
<A href='http://www10.brinkster.com/gezgini/Konular.asp?ad_id=38&amp; - Elektronik Mekani' Target=_Blank>External Web Link</a>
<A href='http://www.transistornet.de/viewtopic.php?p=2353&amp;sid=0cb...08b5da6c07 - TransistorNet.de Thema anzeigen - Rotations Laufschrift' Target=_Blank>External Web Link</a>
<A href='http://www.ispf.de/propclock/ ' Target=_Blank>External Web Link</a>
<A href='http://www.ponnet.com/projects/propeller/index1.0.php' Target=_Blank>External Web Link</a>


Edited by - rickharris on 2/5/2006 9:48:51 AM

Edited by - rickharris on 2/5/2006 9:49:23 AM

Guys! I'm glazing over with all those links- don't forget this Forum supports assorted formating tags! Hence rather than a reader having to tediously cut &amp; paste a URL,the poster should also enclose it in square brackets [ a ] www.yoururl.com [ / a ] - I've spaced them out here -, &amp; a new window will auto open just with a click.

Example - Google is at =&gt; www.google.com <A href='http://www.google.com' Target=_Blank>External Web Link</a>

It seems Hippy &amp; I are the only regulars that use this protocol fully- give it a whirl.



Edited by - Stan. Swan on 2/5/2006 7:37:47 AM

Just me being lazy Stan - sorry

On the subject of POV there has been a TEP <A href='http://www.TEP.org.uk ' Target=_Blank>External Web Link</a>project using picaxe18 to do this and a video of it working.

Edited by - rickharris on 2/5/2006 9:51:32 AM