Go Down

Topic: AS1130 Ongoing Discussion 132 Individually controllable, PWM LED driver (Read 15 times) previous topic - next topic

funkyguy4000

I've been looking at getting copper glads and then making my own 5050 SMD RGB Led boards.  They'd be small enough that I could use my own reflow oven (which i'm going to make once these infernal finals are over) and they'd do what I need.  I'll post pics when I make em.  Eventually i'll make boards with the 5050 footprint as well as 2 1206 footprints for a cool white LED and a B.L. Led.

http://www.ebay.com/itm/170786097936?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

http://www.ebay.com/itm/300757213438?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

I should be able to make about 60 of the boards from a single 9x12 copper clad.  Just need the chems.
Accelerate to 88 miles per hour.

funkyguy4000

Accelerate to 88 miles per hour.

Hexadec

Sponge.
I'm allowed to have it 'cos it's not sharp.

Hexadec

Just a quick update...I've now got the I2C bus running at 1Mhz and it's very stable. I spent a couple of hours today with the 'scope on the SCL pin and by experiment with the resistor values I've now got a very fast rise time on the clock pulses and it's almost a clean square wave. The bus capacitance on these chips is quite high individually and this was causing the problem. I originally used 4K7 resistors and they worked fine @100Khz and not bad at 400Khz...then while playing with changing almost a 1KB of data after a frame interrupt I found that there was a definite visible lag on changeover... :0 I then upped the bus speed in increments of 100KHz until the reliability dropped dramatically.

Anyway...the time between the interrupt firing at the end frame and the start of the new frame PWM set is now very slightly over 217mS which I'm more than happy with. I've ordered some free sample 128KB, 1 MHz I2C EEPROMs from my lovely Microchip (  :smiley-mr-green: ) today so we'll see how fast it runs when pulling data from the external EEPROM...the sky should then be the limit for long animations with full 8 bit PWM... ;)

@Binary
Quote
If you do a software reset and set the shdn-bit to 0, are all controll registers resetted then (set to default
values) ? because thats not written in the datasheet.


We have a saying in English Pantomime....

"OH Yes it is...."  :P

To save you looking (as it's your Christmas present).

If you reset 'shdn' the internal state machine stops and all outputs are turned off.
If you set 'shdn' the internal state machine starts and all outputs are turned on.

So you DON'T lose the register values.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you reset the 'init bit' then the state machine resets and you DO lose the register values.

[font=Verdana]Just like it says in the datasheet.[/font]

Happy New year mate.  :smiley-mr-green:

Sponge.
I'm allowed to have it 'cos it's not sharp.

Hexadec

Oops...forgot to mention...

The CS register is limiting at 15mA and the whole 528 LEDs, four AS1130 chips, 1 512Kb EEPROM and an 18F2550 running at 48 MHz are all powered by the USB....  8)


Here's the usual crappy video...with and without 1 sheet of inkjet paper masking the LEDs.


http://youtu.be/Agxh7WkdDQs


You can at least see how fast the changeover takes place.  :smiley-mr-green:
Sponge.
I'm allowed to have it 'cos it's not sharp.

Go Up