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<p style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;">My prefered chip is the TLC5940: it cam be daisy chained, you can vary each pin's brightness, and it controls 16 outputs at once. You can also use the WS2801 family of chips (some control one LED per chip, some control many LED per chip).</p>
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<p style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;">You're on the right path, thinking of pwm extenders.</p>
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<p style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;">The ws family is cheaper but the tlc are more heavy duty.</p></div><br><div id="fenix-reply-header"><p>On 14-08-01 8:59 Olaf Baumann wrote:<br></p></div><div id="fenix-quoted-body"><div dir="ltr"><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff">Hey Lab,</div><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff"><br></div><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff">
I got some RGB LEDS to play with but when I count the number of pins I need, it doesn't look like I can drive very many.</div><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff"><br></div>
<div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff">The UNO has six PWM output pins and each RGB LED needs three. As the saying goes, twos company, but I want a crowd!</div><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff">
<br></div><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff">With regular LEDs, I used cascading shift registers to allow me to control 24 of them. A great success in my temporarily blinded eyes.</div>
<div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff"><br></div><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff">Is there an analog analogue to the digital shift register? It seems that PWM is a hack for a voltage level, would a steady voltage be better? SPI or I2C would be bonus--maybe I could use an ATtiny85.</div>
<div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff"><br></div><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff">thanks,</div><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff">
Olaf</div><div class="gmail_default" style="font-family:courier new,monospace;color:#3333ff"><br></div></div>
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