8x8 LED MATRIX PWM SPLIT FADING

http://ciruit-ed.com
The 8x8 LED Matrix is connected directly to the PIC microcontroller with no limiting resistors. This demo shows a complex fading process where the center and outside fade-in and fade-out opposite of each other.

Category:

Howto & Style

Tags:

• 8x8
• LED
• Matrix
• PWM
• Array
• PIC
• Microcontroller
• EasyPIC4

[Teknician89]

You say you are running a soft PWM, what kind of algorithm are you using? I have done soft PWM on a 16F628. I take advantage of a math trick to decide when the output should be high or low. Basically, add the desired intensity value to a counter and turn on if carry, otherwise turn off. This separates pulses instead of having them lumped together at one time interval. How are you doing yours? Any more efficient?

[circuited]

PWM is not a math trick, but rather an on/off timing method within a repetitive period ot time. That timing is controlled totally in software in this example.

The program you see was written using mikroBASIC for PIC.

[oehrlein49]

isn't this hard on the LEDs if there are no series resistors?

I think PIC's can pump out ~40mA per pin... right?

[circuited]

If the LED is rated 40ma all is well. Look at my demo video with the Fluke meter and 2-color LED. Most PIC's will souce and self-limit around 25ma @ 5V per pin. PWM also changes the power dynamic on the LED.

[circuited]

Check the datasheets. It is about 25ma each pin up to a total of ~200ma for all pins.

Check my other videos. I have a demonstration to prove it using a meter.

[killguta]

wow cool..... good thing I have my "I-KNOW-ALL-ABOUT-ELECTRONICS" dad to help me learn this stuff :D

[circuited]

Sounds like my dad. So there's hope for you.

[PreadMusic]

@Teknician89 I think he means its a hardware PWM peripheral on the chip that is CONTROLLED by software.

[yo9hnhradio]

@circuited One mistake and your pic is gone :D

Anyway, it's great, nice work !

[vickramlove]

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[pret83]

I have done the same. Each led has a byte, and, when counter + that byte overflows, set 1 or 0 on output pin.

[2011supra]

i can do that pic16F628A with 74hc154 along with 8x16 dot matrix

[IVANLUISLG]

nice !