Thursday, May 14, 2009

$150 robot - Programming board

Part 1 - Building your programming board

This is the board we are going to program our chip on.  We are going to need a place to put the chip, and interface to our programming cable, we will also need power to our board, and an on/off switch is good too, and an led to let us know things are on)

-Learn about power / LEDs and resistors- sparkfun
-Learn how to solder (try google)

-Figure out what chip you are using, how may pins and the pinout evilmadscientist (programming headers), avrfreaks (chips)
-Things you need - Power, switch, led, dip socket, 6 pin/10 pin programmer, 9v bat/wall plug
-Figure out what other things you might want on the board (led tester, breadboard pwr output, more than 1 chip...)
-Layout your PC board, get your needed parts, wanted parts and start sticking things in holesDon't forget the power buses (connect a bunch of holes -if its not already done- and connect it to your power, connect another set to ground) this way you have easy access to all those wires you will have to connect to vcc and ground..  Mark pin 1 of chip and 6/10 programmer on board (both sides) so you don't get confused.  Once you've figured out how you want things arranged you can start soldering (you might want to take a picture first so you remember where things go).
-Solder everything in place. Use your multimeter to make sure you have good connections

Some things I did/learned:
1. USBtiny provides power to the board, but add a 9v battery adapter to make your board portable.
2. Make sure you have atleast 1 extra row beside your dip socket, once your chip is in these let you access each pin with a wire. If you need more than 1 or 2 holes just attach that wire to a small breadboard and go to town
3. You probably only need either the 6 pin or the 10 pin adapter since the USBtiny has outputs for both, but I had room and this way I can use the extra headers to test since they are connected.
4. Switch, mostly important for the battery
5. LEDs let you know if there's power and where its coming from. My programmer doesn't have a tight fit so the LEDs let me know when my cable is loose (which it usually is) and when I have a good connection
6. I didn't get around to adding a socket for a 8pin chip but I left room for it. 8 pin chips are alot smaller (duh) but have basically the same functionality just less input/outputs. I can see this being useful.
7. LED tester, don't like trying to figure out which end is positive and which is negative. I just hooked up 2 female headers and a resistor and marked which is which, so I can just touch the LED to the tester and if it light up I know it works and which end is which.
8. Get a couple of LEDs and solder a resister to the negative end (it doesn't matter which end, just be consistent) now you have plug and play LEDs , which are good for tons of things, stick them anywhere to see if you have voltage, add lights for fun...
9. Find a couple of standoffs, screw them into the corners of you board so it stands up nicely
10. If you have wires coming off (battery in, pwr out, etc) add a bit of superglue to them at the edge of the board to help prevent them from being ripped off, superglue is much stronger than solder!

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