POV Clock

K

kam

Member
Hi All,

Has anyone tried making a POV clock with a picaxe? I couldnt find any info about it on the forum, but then again i may have not searched that well.

I got the idea from this:

http://au.youtube.com/watch?v=no2_M_b059g

I cant figure out how the data would be displayed with the rotation and one LED per row... guess it requires timing issues.

Seems like making a whole new Display panel from the start...:confused:

Any help appreciated.

ThanX
 
B

boriz

Senior Member
I build what I called a TextWand hand held POV device. Here’s the code:
Code: 
eeprom 0,(124,18,17,18,124,0,127,73,73,73,54,0,62,65,65,65,34,0,127,65,65,65,62,0,127,73,73,73,65,0,127,9,9,9,1,0,62,65,73,73,58,0,127,8,8,8,127,0,65,127,65,0,0,0,32,64,64,63,0,0,127,8,20,34,65,0,127,64,64,64,64,0,127,2,12,2,127,0,127,2,4,8,127,0,62,65,65,65,62,0,127,9,9,9,6,0,62,65,81,33,94,0,127,9,25,41,70,0,38,73,73,73,50,0,1,1,127,1,1,0,63,64,64,64,63,0,31,32,64,32,31,0,63,64,56,64,63,0,"ABCDEFGHIJKL",0)
setfreq m8

main:
b4=138
sound 7,(120,1)
pause 60
do
	read b4,b0
	if b0=0 then
		exit
	endif
	if b0=32 then
		pause 3
	else
		b0=b0-65
		for b1=0 to 5
			b2=b0*6+b1
			read b2,b3
			pins=b3
		next b1
	endif
	inc b4
loop
pause 400
goto main
This just displays "ABCDEFGHIJKL" and makes a ‘tick’ sound for hand synchronisation. It uses a Picaxe 18A. The codes represent a 5x7 font.







Works perfectly. Should give you some ideas.
 
A

Andrew Cowan

Senior Member
I researched making a motorised POV display with 8 RGB LEDs, but concluded that a picaxe wasn't fast enough to do it.

A handheld one should work, though.

Andrew
 
D

demonicpicaxeguy

Senior Member
i was looking at a vibrating mirror laser projector, with a pic16f at 20mhz and some dual port memory it shouldn't be too hard, even a low resolution eg 100X100 is enough,
the initial idea was to be able project data onto a wall such as the news,stock quotes,weather, or even simple advertising
 
W

westaust55

Moderator
Have a look at this thread:

http://www.picaxeforum.co.uk/showthread.php?t=10054

I do not think that you will achieve a "fancy" clock like the U-Tube demo using a PICAXE as the PICAXE will be too slow even ran at 8MHz for fast displays and a lot of text.

The sort of "wand" that Boriz has built which may be slower operating can obviously be achieved and might be a better starting point.
 
K

kam

Member
Thanks for the links guys, seems do-able.

Thanks Boriz for the Code and the Pics. I'll try it out.

I was thinking of a few things.

With the motor, would it be a good idea to actually use a seperate controller. I noticed in the video that it actually uses a Floppy or Hard Drive Motor and thats a Spindle. It also requires a seperate sort of drive system. But then again, why would we need a Spindle, Dc would do... but it would be noisy and if one's gonna have this thing in the house, it would get annoying after a while.

Also with the PICAXE not being fast enough, would it be possible to use a 20MHz clock and get away with it?

Any other suggestions Welcome.
 
hippy

hippy

Ex-Staff (retired)
Andrew Cowan said:
I researched making a motorised POV display with 8 RGB LEDs, but concluded that a picaxe wasn't fast enough to do it.

A handheld one should work, though.
Click to expand...
It should work but does depend on the code implementation and speed of motor. A fast PICAXE, 8MHz or, better still, 16MHz or 20MHz, and a sequence of "pins=" will give you the fastest update rate and allow fastest motor speed. It may be possible to output Red in one pass, Green in the next then Blue.
 
S

SD2100

New Member
Here's one I made a while back using an 18x and had it fixed to a bike wheel.
It worked ok at moderate speeds but struggled at higher speeds also you need to get the code running as quick as possible.

Code: 
#Picaxe 18x
setfreq m8
setint %00000100, %00000100

do:loop

Interrupt:
   'P
   pins = %11111110  
   pins = %00010010 
   pins = %00010010
   pins = %00010010
   pins = %00001100
   pins = %00000000
   'I
   pins = %00000000
   pins = %00000000
   pins = %11111110
   pins = %00000000 
   pins = %00000000
   pins = %00000000
   'C
   pins = %01111100
   pins = %10000010
   pins = %10000010
   pins = %10000010
   pins = %01000100
   pins = %00000000
   'A
   pins = %11111100
   pins = %00010010
   pins = %00010010 
   pins = %00010010
   pins = %11111100
   pins = %00000000
   'X
   pins = %11000110
   pins = %00101000
   pins = %00010000
   pins = %00101000
   pins = %11000110
   pins = %00000000
   'E
   pins = %11111110
   pins = %10010010
   pins = %10010010
   pins = %10010010
   pins = %10000010
   pins = %00000000

   setint %00000100, %00000100	
return
 

Attachments

P

picaxester

Senior Member
I made a pov display a couple years ago.
It worked well.
It was rotated with a computer fan motor (I cut off the blades and base).
The power was transfered with two coils, one on the motor and one on a cardboard tube.
The coil was pulsed by a simple transistor circuit.
It was triggered by a IR LED on the base and a IR photo transistor on the rotor.

Here are some pics:
http://i216.photobucket.com/albums/cc41/picaxester/DSCN5653.jpg
http://i216.photobucket.com/albums/cc41/picaxester/DSCN5654.jpg
http://i216.photobucket.com/albums/cc41/picaxester/DSCN5655.jpg
http://i216.photobucket.com/albums/cc41/picaxester/DSCN5656.jpg
http://i216.photobucket.com/albums/cc41/picaxester/DSCN5657.jpg

Maybe I'll try to find a working program and take a video :)
 
P

picaxester

Senior Member
Heres that video :)
The cameras frame rate makes it look worse than it really is.

Heres the code: (keep in mind it was writen a long time ago lol)
Code: 
setfreq m8

b4 = 1

main:
	w0 = w0 + 1
	if w0 = 1100 then clock1
main1:
	if pin1 = 1 then hour1
	goto main1
	
clock1:
	b2 = b2 + 1
	w0 = 0
	goto main
	
mins1:
	if b2 = 0 then pat00
	if b2 = 1 then pat01
	if b2 = 2 then pat02
	if b2 = 3 then pat03
	if b2 = 4 then pat04
	if b2 = 5 then pat05
	if b2 = 6 then pat06
	if b2 = 7 then pat07
	if b2 = 8 then pat08
	if b2 = 9 then pat09
	if b2 = 10 then rsetb2
	goto mins1
	
mins10:		
	let pins = %01101100	
	pause 1		
	let pins = %00000000
	pause 1
		
min10:	
	if b3 = 0 then pat000
	if b3 = 1 then pat010
	if b3 = 2 then pat020
	if b3 = 3 then pat030
	if b3 = 4 then pat040
	if b3 = 5 then pat050
	if b3 = 6 then rsetb3
	goto min10
	
hour1:
	if b4 = 1 then pat001
	if b4 = 2 then pat002
	if b4 = 3 then pat003
	if b4 = 4 then pat004
	if b4 = 5 then pat005
	if b4 = 6 then pat006
	if b4 = 7 then pat007
	if b4 = 8 then pat008
	if b4 = 9 then pat009
	if b4 = 10 then pat0010
	if b4 = 11 then pat0011
	if b4 = 12 then pat0012
	if b4 = 13 then rsetb4 
	goto hour1


rsetb2:
	b2 = 0
	b3 = b3 + 1	
	goto mins1
	
rsetb3:
	b3 = 0
	b4 = b4 + 1
	goto mins10
	
rsetb4:
	b4 = 1
	goto hour1
	


'mins1
pat00:
	let pins = %01111100	
	pause 1		
	let pins = %10000010	
	pause 1		
	let pins = %10000010	
	pause 1		
	let pins = %01111100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto main	
pat01:
	let pins = %10000100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %10000000	
	pause 1		
	let pins = %00000000	
	pause 1						
	goto main

pat02:
	let pins = %10000100	
	pause 1		
	let pins = %11000010	
	pause 1		
	let pins = %10100010	
	pause 1		
	let pins = %10011100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto main
pat03:
	let pins = %01000100	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01101100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto main
pat04:
	let pins = %00111000	
	pause 1		
	let pins = %00100100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %00100000	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto main
pat05:
	let pins = %01011110	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01110010	
	pause 1		
	let pins = %00000000	
	pause 1					
	goto main
pat06:
	let pins = %01111100	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01100100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto main
pat07:
	let pins = %11100010	
	pause 1		
	let pins = %00011010	
	pause 1		
	let pins = %00000110	
	pause 1		
	let pins = %00000000	
	pause 1					
	goto main
pat08:
	let pins = %01101100	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01101100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto main
pat09:
	let pins = %01001100	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01111100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto main

	
'mins10
pat000:
	let pins = %01111100	
	pause 1		
	let pins = %10000010	
	pause 1		
	let pins = %10000010	
	pause 1		
	let pins = %01111100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins1	
pat010:
	let pins = %10000100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %10000000	
	pause 1		
	let pins = %00000000	
	pause 1						
	goto mins1
pat020:
	let pins = %10000100	
	pause 1		
	let pins = %11000010	
	pause 1		
	let pins = %10100010	
	pause 1		
	let pins = %10011100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins1
pat030:
	let pins = %01000100	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01101100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins1
pat040:
	let pins = %00111000	
	pause 1		
	let pins = %00100100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %00100000	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins1
pat050:
	let pins = %01011110	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01110010	
	pause 1		
	let pins = %00000000	
	pause 1					
	goto mins1


	
	
'hour1	
pat001:
	let pins = %10000100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %10000000	
	pause 1		
	let pins = %00000000	
	pause 1						
	goto mins10

pat002:
	let pins = %10000100	
	pause 1		
	let pins = %11000010	
	pause 1		
	let pins = %10100010	
	pause 1		
	let pins = %10011100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins10
pat003:
	let pins = %01000100	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01101100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins10
pat004:
	let pins = %00111000	
	pause 1		
	let pins = %00100100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %00100000	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins10
pat005:
	let pins = %01011110	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01110010	
	pause 1		
	let pins = %00000000	
	pause 1					
	goto mins10
pat006:
	let pins = %01111100	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01100100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins10
pat007:
	let pins = %11100010	
	pause 1		
	let pins = %00011010	
	pause 1		
	let pins = %00000110	
	pause 1		
	let pins = %00000000	
	pause 1					
	goto mins10
pat008:
	let pins = %01101100	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01101100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins10
pat009:
	let pins = %01001100	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %10010010	
	pause 1		
	let pins = %01111100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins10
pat0010:
	let pins = %10000100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %10000000	
	pause 1		
	let pins = %00000000	
	pause 1
	let pins = %01111100	
	pause 1		
	let pins = %10000010	
	pause 1		
	let pins = %10000010	
	pause 1		
	let pins = %01111100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins10
	
pat0011:
	let pins = %10000100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %10000000	
	pause 1		
	let pins = %00000000	
	pause 1						
	let pins = %10000100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %10000000	
	pause 1		
	let pins = %00000000	
	pause 1						
	goto mins10

pat0012:

	let pins = %10000100	
	pause 1		
	let pins = %11111110	
	pause 1		
	let pins = %10000000	
	pause 1		
	let pins = %00000000	
	pause 1						
	let pins = %10000100	
	pause 1		
	let pins = %11000010	
	pause 1		
	let pins = %10100010	
	pause 1		
	let pins = %10011100	
	pause 1		
	let pins = %00000000	
	pause 1			
	goto mins10
 
Last edited:
T

tiscando

Senior Member
I am also making a POV display: I am using an old VCR's Video head drum which is 3-part:) (one is the base, which connects to a shaft, and the shaft connects to the head). I dismantled 4 old VCRs so far, and 2 of them are very identical (including their video heads, which is the 3-part design above:)). At the moment, I am creating a brushless motor driver. See the thread about driving a 3-phase stepper motor.

Can a Vcc square wave be fed into the resonator pins of a 28x1 to allow exact synchronisation for 2 or more picaxe 28x1s?
 
Last edited:
hippy

hippy

Ex-Staff (retired)
tiscando said:
Can a Vcc square wave be fed into the resonator pins of a 28x1 to allow exact synchronisation for 2 or more picaxe 28x1s?
Click to expand...
Possibly not. The problem comes in actually synchronising them. Even if they turn on at the same time I don't know if they would come out of their PICmicro power-up delays at the exact same time so everything could be out of step from then on. You cannot later wait for a separate "go" signal because that lack of synchronisation could mean one PICAXE sees the signal while another has just missed it. That said it should only be a few hundred microsecond out of synch which may be acceptable.

You'll have to look in the PICmicro datasheet to check the OSC input can be fed this way. I expect it can.
 
B

boriz

Senior Member
@picaxester

Nice!. I really like that design. How quiet is it? Can I have more detail about the inductive power transfer?
 
P

picaxester

Senior Member
I think it's just a basic transistor flip-flop circuit like this one but without the leds and with smaller caps. The collectors of one of the transistors goes to the base of a power transistor (maybe through a resistor), which pulses the coil.
The secondary coil is wraped on the fan motor, the two ends of the coil goes to a bridge rectifier (made of four smt diodes), the output of the bridge rectifier goes to a 5V voltage regulator and some caps.
 
A

adumas

Member
Hi Boriz... Thanks for the graphics and the code... I built the same device and it works... Eventhough it is very hard to see all of the letters - lots of waving...

I tried last night to build a motorized contraption that would spin and hopefully display the letters. After a dozen attempts, several hours, I could not get the letters to appear... Am I missing something - shouldn't the letters be able to be displayed eventhough the device is rotating instead of being manipulated from side to side?

Could you let me know - and what I might need to change to get it to work in a rotating manner?
 
A

adumas

Member
Hi, just checking in... Wondered if anyone could answer my last question... I'm pulling out my hair trying to get this to work...
 
P

papaof2

Senior Member
A rotating device needs some type of position sensor to tell the chip when to start displaying. This could be a switch that is tripped by a cam once per revolution or an optical solution (LED + phototransistor).

John
 
S

SD2100

New Member
If displaying a message on a rotating thing you need to sit in a loop and wait for a position sensor to be triggered then display the message, this way the message is always displayed in the same position. Something like the code below is needed.

Code: 
#picaxe 18x

setint %00000100,%00000100   'Setup sensor interrupt on pin2

main:
    'Wait here until position sensor causes interrupt
    goto main
	
Interrupt: 'Comes here when rotation sensor is triggered
	'****
	'Display message code goes here
	'****
	setint %00000100,%00000100   'reset int when finished displaying
	return   'go back to main loop and wait for next rotation
 
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