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Topic: Beginner - Need help understanding how to wire up the "word clock" (Read 506 times) previous topic - next topic

rkstiner

I'm an absolute beginner when it comes to arduino, electronics, etc. To be honest, I'm not even very good at physics. I got interested in learning it and started with the word clock. - http://www.instructables.com/id/Sleek-word-clock/?ALLSTEPS - I didn't really learn from the ground up (which I kind of regret), but instead I just read a ton about what other people had problems with, and looked everything up as I went. I felt like I had a fairly good grasp of what's going on, but then...I hit a wall.

I'm done with the physical clock and I tried wiring it up yesterday. I have an arduino UNO. My understanding was that I'd wire everything up using a breadboard to make sure it works, then I'd solder everything to perf boards and I'd transfer my atmega to a perf board and follow something like this - http://itp.nyu.edu/physcomp/Tutorials/ArduinoBreadboard - to make it a standalone arduino.

Now, I'm following this schematic - http://www.highonsolder.com/display/ShowImage?imageUrl=/storage/WC/Word_Clock-Schematic.JPG?__SQUARESPACE_CACHEVERSION=1294531692634 - but I'm really confused as to the connections leading into the atmega. I've already made the standalone "arduino". I ran "blink" on it to check that it was working, and it was. It also has an indicator LED that I haven't had any trouble with. Then I hooked it up to the rest of the clock circuit. So I loaded the clock program on the chip using the arduino, and moved that to the breadboard. But now, it won't work. I even took the chip out, uploaded "blink" again, and when I put in back in the standalone it doesn't work. I'm not sure, but I'm thinking this might have something to do with "RX", "TX" and "RTS". Currently, none of these pins on the atmega (1-3) is hooked up to anything.

Any help would be SO appreciated! I tried to do my homework, but it's a lot more helpful to get feedback from an actual person. Thanks so much in advance.

johnwasser

Diagrams on this page...

http://www.sproboticworks.com/products/electronic-components/atmega-328-20pu-arduino-bootloader.html

...show what ATmega328 pins correspond with what Arduino pins.  Your schematic is for the ATmega pins and whatever sketch you write will probably be using the Arduino pin numbers.
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rkstiner

Oh, I see! So I should change the program according to the new pin numbers? I didn't do that. The only problem is I did account for that in "blink" (hooked the LED up to 19), and it's not working either...

Also, I guess what I really don't understand is - what should RX, TX, and RTS on the atmega be hooked up to?

After you're done programming RX and TX dont need to be connected to anything. Reset is connected to 5v (through a resistor if you want to be able to reset). Keeping it pulled up to 5v keeps it from resetting randomly. The numbers of the chip (1-28) do not correspond to the pin numbers in the programming at all. You have to look at one of those diagrams to see which is which. For instance digital IO's #9-13 are chip pins #15-19.

If you uploaded blink, put it on a breadboard and connected the LED to pin 19, then that is the right idea. Make sure reset is pulled up to 5v. If it still doesn't work check your wiring. Go through the standalone tutorial again and check everything.

johnwasser


Also, I guess what I really don't understand is - what should RX, TX, and RTS on the atmega be hooked up to?


Looks like they go to a 6-pin header to which you connect a USB-to-Serial (a.k.a. "FTDI") cable.
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