Re: LED brightness control

Hello Joris,

Well, yes, the control register is to address each LED. You can set it to auto-increment when you want to write all of their PWM registers sequentially. If you want to write just to the PWM of one particular LED then address it directly.

I believe you interpret this incorrect. Increment means the next register (so next register number) is written. Otherwise they would have made some really strange device, if you have to program all the PWMs just to modify a single one.


You don't have to program them all, IIUC. Say you'd like to set LED3 from 212 to 196. It starts at LED0, then you increment once, twice and at the third increment you are at LED3 which you can then change. The others you'd just leave alone because they didn't need to be changed.


After you wrote to all of the PWM registers or at least to the ones where you have LEDs connected you can then switch each LED to its own 256bit PWM, to the slow blink, to full on or to off.

At least that's how I understand it and this would corroborate what they state on page 2 "...blink rates / duty cycles for each individual PWM".


So I'm sure you interpreted it wrong here. If you read somewhere further down you see an example of using the 'auto-increment' function, which just traverses the registers you see listed.
That would be page 11 actually.


Well, I am not a programmer. But the example on page 11 shows that this chip seems to be able do what you originally wanted to do, to set the brightness level of each LED individually. The exact order of code needs to be gleaned from the data *** and that takes more time than just a brief look. The uC can feed it whatever sermon the data *** says it wants to get to the desired register.


Probably some marketing dude interfered with it, because it is possible, but in a limited way.


Easy on the marketeers. I am married to one...

But what's limited here? If it has 16 fast PMWs and another 16 slow PWMs and all can be individually programmed, what more do you want? Ok, the chip needs series resistors for the LEDs which ain't so nice. Probably they didn't want to spring for the thermo-package. And it's over a Dollar which doesn't sound too great if you can upgrade the uC to one with enough extra port pins for less. But you'd have to check whether the uC can really stomach the LED currents at the port pins. Some are spec'd as wimpy, like the MSP430 with 2mA (where everybody knows it can do a lot more...).

There is one issue that causes me to be cautious with some of the specialty chips from EU companies. I have seen too many of them vanish into lalaland. Then the purchasing manager comes running down the hallway all red in the face.


Maybe a day to finish by popping the cork on a nice bottle of Trappiste or Chimay ;-)

I'm seeing I'm doing well. That's usually the result of me doing multiple things at the same time. It had it twice today that someone called me to inform that I had a meeting. I had 3 meetings totally today. Looking at my time zone, it looks more like starting it with some alfa, leffe or hoegaarden (some good dutch beer).


Hah, I am self employed. Not many meetings, usually :-)

Hoegaarden is nice. You could chase it with a Beerenburger. But leave the car keys for the night, don't drive.

Groetjes, Joerg

http://www.analogconsultants.com
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