ipernity: RGB Matrix by .:madworm:.

Folder: Electronics

Playing with LEDs and nice colors. This project is officially retired. Design files and code are available via my blog / github.

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8x8 RGB Matrix board V2 - schematic

25 Feb 2009

419

I just did this for learning KICAD

8x8 RGB Matrix board V2 - layout

24 Feb 2009

376

This drives an 8x8 RGB matrix with PWM using Arduino code and DIP parts. Adding stacking headers will force me to switch to SMD parts in the end. I just did this for learning KICAD

8x8 RGB Matrix board V2 - 3D

24 Feb 2009

323

I just did this for learning KICAD

Logic vs. transistor driver

15 Dec 2009

144

0.1ms/div 2V/div CH1: Row 1 74HC595 CH2: Row 4 74HC595 This is the good looking control signal for the led matrix row source driver. No overlapping or anything nasty.

Logic vs. transistor driver

15 Dec 2009

153

5ms/div 2V/div CH1: Row 1 UDN2981A CH2: Row 8 UDN2981A During the LOW period of the signal the cpu has time to service other interrupts and run user code.

Logic vs. transistor driver

15 Dec 2009

136

2ms/div 2V/div CH1: Row 1 UDN2981A CH2: Row 8 UDN2981A PWM cycle of the rgb led matrix. The interrupt code runs when the signal wiggles. Each little dip scans the whole matrix for one brightness step. 32 scans make up the whole PWM cycle. You can also observe an interesting effect here. The color that was displayed on the matrix has a hue value of 200, which translates to (0.000,0.666,1.000) in RGB. To set the status bit for a color to "on", the code nees to run 1 command, to leave it "off" nothing has to be processed. Therefore the code finishes a bit earlier. In the photo you'll see a slight difference near 2/3 of the wiggles. The period changes slightly from about 6 to about 7 wiggles per div. In this case you can guess the duty cycle of 0.66 for one color. It only works, as for red it is always 0 and for blue always 1, so only green changes at some point of time.

Logic vs. transistor driver

15 Dec 2009

149

0.1ms/div 2V/div CH1: Row 1 UDN2981A CH2: Row 4 UDN2981A The output of the led matrix row source driver. The signals overlap which explains the ghost images. This was measured without load btw. I need a digital scope with deep memory to have a look at this type of signal more closely. Triggering is very hard, as there is always some jitter and the signal is not necessarily periodic.