pic controler +74HC595 Shift Register Help!

[nosrak113]

Hi I’m new at making matrixes
Is it possible to control 8 74HC595 Shift Register differently with one pic micro controller so I can control each led?
If so can u suggest a microcontroller?
If any of this is wrong tell me to shut up plz no flaming thz in adv
-nos

[justDIY]

it depends on what you mean by differently.

in simplest of terms, think of the 595 as 8 switches that can be turned on and off by the computer ... it may also help to visualize each 595 as one "byte" in a buffer ... if you have eight 595's, you have an eight byte buffer.   you can control each bit in each byte of that buffer, so the same holds true for a 595

in my rainbow chaser project, I used three 595's connected in a daisychain to control 24 leds (eight rgb leds) ... I created different patterns by changing the bit sequence sent out to the string of 595s ... if there were leds that I didn't want changed, I just left their bits alone in the buffer

since the microcontroller pushes data out to the chips so quickly (20mhz / 8 = 2.5mhz serial clock estimated), the registers update so fast you can even do fancy things like time domain division... giving leds the appearance of different brightness levels (the waveform looks like pwm), but that is some fancy programming!

any microcontroller will work ... it depends on your application ... the inexpensive 16F628A or 16F88 are good all-purpose chips to start with ... the 12F683 and 12F639 are economical and very small pics, but are still very capable of running a large register of 595's.

[nosrak113]

What do u think would be more productive get a 16bit microcontroler with 2 bit shifters in series to  make a 16 bit one  orget a 8 bit controler with 2 shifters?

[justDIY]

the instruction size (or internal processor arrangement) of a microcontroller has little effect on anything when controlling simple devices like the 595.

if you're more comfortable with a 16 bit cpu (or 32 for that matter), by all means ... but this takes you out of the realm of the normal pic microcontrollers ... the new 24F chips have a 16 bit cpu, but most of them are still in pre-production, so you'll want to look at TI, Samsung, Motorola... most of these are much harder to program than a PIC however.

[nosrak113]

would the micro controlers u recomended above control 32 595 Shift Register, so I could have a 16X16 aray?
if not recomded a better one thz alot for you help already

[justDIY]

for a 16x16, you need 4 registers, not 32?

two for the 16 rows, two for the 16 columns

[nosrak113]

but it does not allow shapes or letters with holes in it like... for example
 0000000000000000
 0000000000000000
 00000XXX00000000
 00000X0X00000000
 00000XXX00000000
 0000000000000000
 0000000000000000
 0000000000000000
/\ /\this is imposable, if i set this up it would produce \/ \/
 0000000000000000
 0000000000000000
 00000XXX00000000
 00000XXX00000000
 00000XXX00000000
 0000000000000000
 0000000000000000
 0000000000000000
if im wrong yell at me ,but it in right can u u ansewer the perveuse post question

[justDIY]

my recommendation of microcontrollers hasn't changed, see my first reply to your question

to draw shapes or letters in a matrix, you need to 'strobe' the matrix ... you light one LED at a time, or one entire row at a time (depending on how your drivers are setup)

you do this so fast (easily with a microcontroller), and you get the apperance of a solid picture

check out multiplexing and led matrix drivers on google

see here and here for my thoughts on LED matrix's

[nosrak113]

thank you so much it would have taken me a long time time to get this info
last question say if i wanted to use eletro magnets insted of leds to control ferrofuild would that make a difference exsept for the voltage?
thz

[justDIY]

I don't think it would work at all

ferrofluid is a mechanical substance, it takes a "LONG time" to react in comparison to an electronic device such as an LED whose response is instant as far as we're concerned.

if you could take the time to lay out your project goals and ideas, perhaps someone will have some ideas for you.

[nosrak113]

basically i want to recreate
http://www.digital.udk-berlin.de/en/projects/winter0405/main/hauptprojekt/snoil.html

[justDIY]

i finally was able to download and watch that video for snoil ... I must say, that's quite a creation

did you see the circuit boards inside that thing!  the 595 is but a tiny slice of the much larger pie.  if you're serious about trying to reverse engineer that, it looks like a very steep learning curve is involved... I dont think anyone here will just whip out a schematic for you!  If it were me, I'd start with something like a 2x2 matrix, and work up.

[nosrak113]

it does not look at hard http://64.233.179.104/translate_c?hl=en&u=http://www.freymartin.de/blog/archives/2004/12/index.html&prev=/search%3Fq%3Dhttp://www.freymartin.de/blog/%2Bnov%26num%3D100%26hl%3Den%26lr%3D%26newwindow%3D1%26c2coff%3D1%26safe%3Doff%26sa%3DG
http://64.233.179.104/translate_c?hl=en&u=http://www.freymartin.de/blog/archives/2005/01/index.html&prev=/search%3Fq%3Dhttp://www.freymartin.de/blog/%2Bnov%26num%3D100%26hl%3Den%26lr%3D%26newwindow%3D1%26c2coff%3D1%26safe%3Doff%26sa%3DG
i just do not understand what the flip flop does

[cadstarsucks]

two 74ACT573s will directly drive the low lines and one with decoders with FETs to drive the high lines.  Driving the registers BYTE serial instead of BIT serial saves enough time that a PIC might be able to handle it. 

I have been able to scroll words on a 640 LED array with an 89C51 on a 12MHz crystal so you should be able to get a PIC at 40MHz to do it.  While PICs are pretty useless when it comes to performance per dollar they are more common among hobbyists.

For a speed reference the 12MHz 89C51 was running a 1uS per instruction while a 40MHz PIC (18F1220 @ $4.50 in single piece QTY) 25nS per instruction if memory serves.

To drive a matrix you would send out 3 bytes, 2 for the low lines and one that will drive one FET at a time.  You need to change which column you drive at least 1600 times a second.

You would not even need the registers accept then you need 20 port pins to drive the display.

http://forums.linear1.org/index.php/topic,1253.0.html

[justDIY]

dude, this thread is over two years old