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Topic: Daisy-chaining 7 IC's (Read 6441 times) previous topic - next topic

CrossRoads

Stranded is easier to work with.
I use these when I prototype.
http://www.nkcelectronics.com/breadboard-jumper-wire-70pcs-pa70.html
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Nofew

Stranded's easier to work with, but is solid better for not running into the situation I was just in?

I might slow it down, I don't know if I can get this to reach all the way down to the end of my second breadboard.. Hopefully it'll keep up. I've already found out that 57600 baud is *barely* enough for 20 events/second and that's the fastest the software controlling it allows. How much slower would setting SPCR to 3 make things? Still enough for 57600?

CrossRoads

The solid ends on the stranded jumper wire make for nice connections.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Nofew

I knew that. I have some of those wires you linked to and I agree, they're far nicer than just plain stranded wire when you're trying to get them into a breadboard, but what carries a signal better?

Graynomad

Quote
How much slower would setting SPCR to 3 make things?

Probably better to use the official API

How much slower would setting SPCR to 3 make things?

You can adjust it to 7 different speeds. So

SPI.setClockDivider(SPI_CLOCK_DIV2);

Is probably the default (8MHz) and i would think what you are current using.

SPI.setClockDivider(SPI_CLOCK_DIV4);

would give you 4MHz etc etc.

You do the maths :)

Quote
but what carries a signal better?

At these slow speeds I doubt it matters.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Nofew

Got'cha.

One other problem just popped up. Literally. The IC's are having issues staying in the breadboard. Sometimes one end pops up a bit, sometimes the entire chip pops out. Are there any tricks to keeping them in?

dc42

What happens if you double the values current setting resistors on the TLCs? If that gets it working, then it would indicate that it is the LED switching current that is causing the problem, and better grounding/decoupling is the solution.

Stripboard is easy to work with once you learn how to use a soldering iron.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

Nofew

I'm not sure -- Kinda hard to check now since it's working fine. Like I said though, the PSU isn't even the same for the IC's anymore. Got two PSU's, one just for the LED's, and it's helped a lot.

I know how to solder, but what do I do to make connections on a stripboard? Using wires sounds "wrong" and so does making long solder bridges..

Graynomad

Bend component leads if they are long enough to reach another component.

Just use the strips themselves for low-current signals.

Use the strips but run a bare (thick) wire as well and solder it all along the strip for high-current.

Use wire for any connections that don't fit the above.

BTW, the best way to cut strips is a 1/8th" bit in a pin vice. Just drill enough to cut the track.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Nofew

Annnnnd scratch that. Broke again. Just the 5th chip. Since the 5th is on a different breadboard I had to use longer wires and that seems to have killed it again. Before it was connected directly but I was gunna run out of wire and space to plug stuff in. Maybe if I tore off the little +V and GND rails on the sides of the breadboards and used those..

I can't adjust the SPI clock -- I think the library does it at some point by its self. I decided to try "bitbanging" instead SPI just to see if it'd work (It says it's slower), but that seems to be too slow for the TLC's to accept.


Man, these things are /really/ sensitive..

Graynomad

#55
Nov 09, 2012, 09:57 am Last Edit: Nov 09, 2012, 10:02 am by Graynomad Reason: 1
Quote
but that seems to be too slow for the TLC's to accept.

SPI doesn't normally have a minimum speed.

Did you try using shiftOut()?

Quote
I think the library does it at some point by its self.

Why do you say that? Looking at the source code I can see nowhere that is changes the speed except in the setClockDivider() function.

EDIT: You're not constantly calling SPI.begin() and SPI.end() are you?

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Nofew

Didn't try shiftOut(), and I really have no idea anymore. My head's fuzzy, I've been at this for weeks now so I'm starting to skip over simple stuff (see hz/mhz confusion) and it's four in the morning so that ain't helping much.

I'll work on it some more later. I just gotta figure out some way to get the chips to stay in the breadboard now. Seems like taking two of the power rail bus type things off the breadboards and using them is working. Maybe. I hope.

CrossRoads

Sounds like its time to firm up the assembly.
Get some perfboard, some wirewrap sockets, and wire up a real assembly.
Wirewrapping is nice, goes quick, easy to correct if you miswire something or need to make a change.
This board only took an evening to build up for example.
You can see the '328 & crystal/caps that make up an arduino, and some shiift registers above it.
On the left is a MIKROE483 FTDI module for USB interface to a PC.
Add your TLC5940s and LEDs next to them, be an easy wiring  job.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Nofew

Where do I get that ribbon cable? I've been looking all over for that and the best I can find is discontinued IDE cables at Radioshack that I'm running out of. x.x

CrossRoads

I think that particular cable was from here
http://www.dipmicro.com/store/index.php?searchStr=ribbon+cable&act=viewCat

crimp on connector
http://www.dipmicro.com/store/index.php?searchStr=idc&act=viewCat

If you need wider connectors, you can get them here, I bought 14s & 16s recently.
http://www.king-cart.com/phoenixent/product=RECEPTACLES-SOCKETS+IDC+.1SP+%2526+2MM+SP/exact_match=exact
Can be found at digikey, mouser, pain in the butt locating them.

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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