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Author Topic: Controlling/Strobing 60 LED'S  (Read 3424 times)
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You circuit looks OK to me except that you also need a 100nf capacitor between the Vcc and Gnd pins of the mcu, as close to the mcu as possible. Another 100nf between Avcc and Agnd is also recommended. The pushbutton wiring is ok. I haven't checked the pin numbers on the TQFP package.

Regarding the crystal pins, if you want to run at 16MHz then the simplest solution is a 3-terminal 16MHz ceramic resonator, centre pin to ground, outer pins to xtal1 and xtal2. Alternatively, a 16MHz crystal between xtal1 and xtal2, a 22pf cap from xtal1 to ground, and a 22pF cap from xtal2 to ground.

Total current consumption will be around 400mA at full brightness (i.e. 12 x 30mA = 360mA, plus 20mA or so for the mcu). So at 13.5v supply voltage, if the the 5v regulator is a linear regulator then it will dissipate about (13.5 - 5) * 0.4 = 5.4 watts, which will require a heatsink.
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So like this? Then add the another two for Avcc and Agnd?

I'm not familiar with the crystal pins or their purpose. Is that something I need for this?

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No. Connect AGND to GND as you did before, and Avcc to Vcc as you did before. The add a 100nf capacitor between the Vcc pin and the Gnd pin. Add another 100nf capacitor between the Avcc pin and the Agnd pin. These capacitors will be in parallel on the schematic. When you lay out the design, place them physically close to the mcu pins they are connected to.

You can dispense with the crystal if you use a mcu that had not had the bootloader installed and you do not require accurate timing, then you can run it from the internal 8MHz clock.

You should also add a standard 6-pin ICSP header to your design so that you can program the mcu in-situ. The header connects to Vcc, gnd, reset, mosi, miso and sck. Look at any Arduino schematic to see where each of the header pins should be connected to.
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I started to take a look at the board view and some things don't appear to be wired the same as they we're in the schematic. Is this normal or am I doing something incorrectly?

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I think the problem is that in the board view, some of your "wires" are going directly over other connections, so they look as if they are joined together. It may make more sense if you rotate the resistors and the mosfets through 90 degrees in the board view.
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That seemed to fix some things, but there still seems to be something weird going on with the VCC and GND inputs around the regulator area.

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Also, I just started to test things out on the programming side. I'm trying to blink the LED's using the TIP120 (haven't receive my mosfet's yet). It works when not using the TIP120, but it seems almost as if the TIP120 isn't cutting off right away and the LED's stay solid and don't blink, but just barely dim. Am I going to have this issue with the MOSFET also? What can I do to fix it?
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It sound to me as if you have the TIP120s wrongly connected.
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Cleaned some things up, added the ICSP Header. Added the capacitors by the MCU. How does it look, are the resistors and everything I added for the reset pin correct?

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The ICSP header bits you added are not right. See the connector marked ICSP in http://arduino.cc/en/uploads/Main/arduino-uno-schematic.pdf for the correct connections to the MCU. As for the reset pin, all you need is the connection to the ICSP header, although some folks add a 10k pullup to +5v as well (it's not strictly necessary because the mcu already contains a 60k pullup). Ignore the capacitor going to the DTR pin, that's for auto-reset when uploading software via the bootloader, so you don't need it unless you plan on using a serial interface for programming instead of ICSP.
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Okay, having that will allow me to program using my Arduino right? (http://arduino.cc/en/Tutorial/ArduinoISP)

Updated:

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Okay, having that will allow me to program using my Arduino right?

Yes, see http://miscsolutions.wordpress.com/2011/08/09/prototyping-small-embedded-projects-with-arduino/ for how I do it.
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How's this looking?



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