Hello World,
Thirth week...still not a working answer! :
Which driver can I use for my 4x4x4 or just a normal 8x8 RGB common CATHODE LED matrix??
I want to fade the leds! It have to fade like the cube become from full to empty.
I can't use the TLC5940 because it's build as a common ANODE structure and also the MAX7219&7221 is only for on or off and not good for fading.
Does anybody know which driver I CAN use!! Please... :-[
Actually the MAX7219 can fade, with two limitations
[1] You fade ALL leds at the same time (sounds like this is what you want)
[2] There is only 15 brightness levels from full on to full off (you don't specify how many levels are needed)
Actually the MAX7219 can fade, with two limitations
[1] You fade ALL leds at the same time (sounds like this is what you want)
[2] There is only 15 brightness levels from full on to full off (you don't specify how many levels are needed)
Thnx Trialex,
[1] Can I fade only one layer at a time?? I have 4 layers of 16 RGB LEDS. I want to fade the upper layer first than the second till the last layer!
[2] Cool that would do the job I think! Do u know if I can use the MAX7219CNG+?? http://www.farnell.com/datasheets/63797.pdf
grts,
Michel
If you use 4 chips, yeah, you can fade each chip individually by using a digital potentiometer on each, you can control the digipot with th arduino
If you use 4 chips, yeah, you can fade each chip individually by using a digital potentiometer on each, you can control the digipot with th arduino
What?!?
If I'm right, you can set the overall intensity of the leds with a resistor wired between your V+ and the ISET pin on the MAX7219/7221. If you use a digipot, you can change the value of this resistor with the arduino.
Hum, wait, I just read the datasheet (once again) and you can directly write a register on the chip (Intensity, adress 0xXA).
Datasheet :
Digital control of display brightness is provided by an
internal pulse-width modulator, which is controlled by
the lower nibble of the intensity register. The modulator
scales the average segment current in 16 steps from a
maximum of 31/32 down to 1/32 of the peak current set
by RSET (15/16 to 1/16 on MAX7221). Table 7 lists the
intensity register format. The minimum interdigit blanking
time is set to 1/32 of a cycle.
If I'm right, you can set the overall intensity of the leds with a resistor wired between your V+ and the ISET pin on the MAX7219/7221. If you use a digipot, you can change the value of this resistor with the arduino.
But I don't want to entirely fade the leds, I want to fade only parts of 16 leds at a time.
But I don't want to entirely fade the leds, I want to fade only parts of 16 leds at a time.
OK no you can't do this with MAX72XX, as i said in my earlier post it's EVERYTHING connected to the chip at the same time. Sorry wasn't sure exactly what you were asking for in your original post.
But I don't want to entirely fade the leds, I want to fade only parts of 16 leds at a time.
OK no you can't do this with MAX72XX, as i said in my earlier post it's EVERYTHING connected to the chip at the same time. Sorry wasn't sure exactly what you were asking for in your original post.
Then tell me please, what driver can???
Then tell me please, what driver can???
I think this thread is going round in circles. The consensus appears to be that there is not an LED driver that will allow you to fade individual LEDs that is wired for common cathode devices. That's why you have not had a reply before. As I see it your only hope is to take what the TLC5940 does and implement it in firmware. This will probably tie up a whole ardinuo.
Anyone disagree?
Then tell me please, what driver can???
I think this thread is going round in circles. The consensus appears to be that there is not an LED driver that will allow you to fade individual LEDs that is wired for common cathode devices. That's why you have not had a reply before. As I see it your only hope is to take what the TLC5940 does and implement it in firmware. This will probably tie up a whole ardinuo.
Anyone disagree?
thnx for your reply,
A specialist is coming to show me how he worked with the cathode leds and the max7221. He said that u can fake the fade with intensity or something. But I like to try the TLC as well, so I ordered anode rgb leds and the TLC.
Thnx everyone anyways for all your reply's and support.
I'm waiting on my drivers and leds, so I'll take a 10day break and going to Sonar festival in BarcelonaGreets,
Michel
macegr apparently used "common-cathode RGB LEDs and a p-channel MOSFET to power each red, green, and blue anode rail. " with a TLC5940.
So you would have to synchronises the FET switching to the scanning, is that done with the Arduino or with some external logic?
No idea, I have to go buy some FETs to try it myself. Maybe macegr can give us some more infos ? ^^
OK but that would also mean that all three LEDs (RGB) would be at the same brightness with limited colour mixing.
The idea is to send a command to the TLC5940 right before you're about to switch to the next FET, then hit the LATCH and BLANK as you switch to the next color. It's multiplexing, you can adjust each color of each LED individually.