Ouch, hot!

The first step is to solder the kit together. If you've never soldered before, check the Preparation page for tutorials and more.

Check the kit to verify you have all the parts necessary, read the parts page for a list of parts you should have in your kit.
Get your tools ready! A board vise, soldering iron & solder, diagonal cutters, and a solder sucker (desoldering tool) if you have one.

Next, get ready by placing the PCB in a vise so that you can easily place and solder the parts in!

Check also that you have all the tools you need, & warm up your soldering iron to 650-700degF.

The first part to solder is a resistor, R1. This resistor has a 47ohm value, check the parts list to make sure you have the right one. Bend the two legs of the resistor so that its staple-shaped. Then slide the resistor into the PCB so that the outline matches the image on the silkscreen. Resistors are bi-directional so you don't have to worry about putting it in the wrong way.
Bend the wire legs so that when the board is flipped over, it won't fall out.

Next, with your soldering iron, solder each of the resistor legs. Place the tip of the iron against both the pad (ring) and lead (leg) and after a few counts, touch the solder in, to make a nice joint.

Repeat for the other joint.

Next, clip the excess leads using the diagonal cutters. Clip right above the top of the solder joint.
When you are done, it should look like this. If you have some sticky stuff on the solder joints, that's OK, that's the rosin inside the solder that protects the joints from oxidation. It isn't necessary to clean it off.

Next is the other 47 ohm resistor, R2

This one doesnt sit flat like R1, so bend it over as shown. Again it doesnt matter which end goes where since resistors work both ways.

Solder the resistor just like you did with R1.
Then clip the excess wire off.

Now that you have a lot of practice with resistors, you can do the remaining 5 all at once. Place R10 (10K pullup resistor), R3, R5 and R6 (1.5K resistors for the USB connection, LEDs and output buffer).

If you are using the UsbtinyISP with a SpokePOV kit, install R4 and R7 (1.5K) as well. If not you may want to switch these resistors for jumpers (see the second photo for a 'finished' shot) as it will mean that target boards with loaded pins can be programmed.

Note: sometimes the 74AHC125 is a bit larger than the silkscreen so you may want to put R7 in later, once the chip is in place.

Solder and clip all of the leads.

Next are the two 3.6V zener diodes, D1 and D2.

These diodes help convert the voltage from the microcontroller down to 3.3V, safe for the USB connection.

Diodes, unlike resistors, have to be placed a certain way or they won't work at all. Each diode has a small black line at one end. Make sure that this end matches with the white line on the silkscreen image. (See left)

Solder and clip the diode leads.
Next is the socket for the microcontroller that does all the hard work. A socket is useful because you can replace the chip in case of upgrade or damage. Sockets have a little notch in them to indicate which way to put in the chip. This notch should match the notch in the silkscreen image, in this picture, the notch is on the left-hand side.

Tack two opposite corners of the socket, to keep it in place, and then solder all the pins.

No clipping is needed as the socket pins are quite short already.

Next to be placed is the 74AHC125 buffer. This chip does a level-shifting conversion on signals from the USBtiny microcontroller to the device being programmed. This way you can safely program chips that vary from 1.8V to 5.5V voltage.

Integrated circuits must be placed correctly, check that the notch in the end of the chip matches the notch in the silkscreen image.

When ICs come from the factory, the legs are angled out somewhat which makes it difficult to insert them into the PCB. Prepare them for soldering by gently bending the legs against a flat tabletop so that they are perfectly straight.

Solder each pin of the buffer, you won't need to clip the leads as they are quite short already.

Next is the USB connector and the 12.00MHz ceramic oscillator. The USB connector is what we use to plug into the computer, the oscillator makes sure the USBtiny microcontroller runs at the precise rate necessary to communicate at the very picky USB protocol rates.

The oscillator can go in 'either way', they're made to be symmetric. The USB connector should snap in easily.

Solder in the three-pins of the oscillator and all 6 pins of the USB connector. Make sure to not bridge any of the square-pins and put plenty of solder on the mechanical tabs. These provide the resistance when you plug in a cable so it's important that they are soldered well, as shown here.
Although they are short, you should clip the pins to the oscillator if possible, to make sure they dont bend over and touch another component.

Next are the two indicator LEDs, green LED2 and red LED1. These LEDs let you know that the USB device connected successfully, and is in the process of programming the target device.

LEDs are diodes, and must be placed correctly or they wont light up, which is very confusing. Make sure the longer (positive) lead of the LED goes into the hole marked with a +. See the images to the left.

The LEDs are also supposed to be very close to the top of the enclosure, so that you can see the light through the drilled holes, when you bend the leads, make sure the LEDs stick out about 1/2" above the PCB.
Solder and clip the two LEDs.

Next are the two capacitors, C1 and C2. These provide some power supply filtering so that the USBtinyISP is less flakey. C1 goes in the corner next to the USB connector. It is a non-polar ceramic capacitor so it can go in either way.

C2 is a polarized electrolytic. It must go in only one way. Make sure the longer leg of the capacitor goes into the hole with a +. Bend the capacitor so that it lies on top of the buffer chip.

Solder and clip both capacitor's leads.

Almost done! The last set of parts are the headers for the cables, and the jumper header. The 10-pin box header has a notch in it, make sure it matches up with the silkscreen, as shown.

The 6-pin header goes in with the long pins sticking up.

The 2 pin jumper has the long pins pointing out.

Solder in all the pins of the headers. You won't need to clip them as they are already quite short.

Finally, straighten the pins of the microcontroller and place it, so that the notch in the chip matches the notch in the socket (and the silkscreen) as shown.

Now go on to make the cables and put the PCB in the case.

If you're not using the USBtiny to talk to a SpokePOV kit, and if you are using a target that has some load on the SCK and MOSI pins, you may need to replace R4 and R7 with jumpers as the 1.5K resistors will have trouble driving the load!

Make 6-pin cable (Old kits, without pre-made 6-pin cables)

There are two standards for AVR programming, 6-pin and the 10-pin headers. Therefore, it's important that an AVR programmer have both types of cables. The 10-pin cables are easy to come by, but the 6-pin ones must be custom made. However, making a cable is super easy, just follow these steps!

If you're using the adaptor for a spokepov or don't need the 6pin cable, you can just skip this part.

It's hard to find 6-conductor ribbon cable so you may end up with 10-conductor wire. (The kit ships with 6-conductor) If so, just use your diagonal cutters (or a knife) to cut a notch so that the red stipe is on the 6-conductor side.
Tear the cable, it should come apart cleanly.
You are now ready to assemble the cable.
It's important that the key (the bump in the connector) and the red stripe line up. Match the image on the left, just poke the conductor in with a mm or two past the edge.
Get it started by just squeezing it with your fingers to make sure the wires are aligned properly. You won't be able to finish the cable this way so dont try!

Do not use needlenose pliers to try to press the pieces together. You have to have very flat pressure from both sides.

For example, use the flat side of a tool to press against a table top.

Or better yet, a vice! Slowly squeeze the two sides together until they lock.
Do the other end, keeping track of the key and red line.
Yay! You've got two cables!


Finally it's time to put the programmer in the case for use.

Take the PCB, two case halves and the cables you've made.

Plug in the two cables as shown, the red stripes on top and so that the cables don't bend over the plug (the case wont fit).

Put the PCB into the bottom case half.

The 6-pin cable may have strain reliefs that can clip on. You don't really need them but if you do want strain relief, put it on the one that goes to the target: the cable won't fit in the case if the strain-relief bit is on.

Line up the LEDs and snap the top on. You're done!

Next up, read the usage manual.

Can't get it working? Don't worry, help is available in the forums!

This guide was first published on Jun 10, 2013. It was last updated on Mar 08, 2024.

This page (Solder it!) was last updated on Apr 02, 2013.

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