Test it

These are the instructions for building a FIGkeys 1.1 board, section 2: TESTING!

OK, now you need to start checking things.Turn the PCB upside down and carefully check all the joints. Make sure all your connections look good. Good connections tend to look nicely cone shaped. Actually, I’m afraid mine don’t always look ideal, but I do know from experience that when you’re soldering there’s a point where the solder seems to just suck itself onto the pins and pads to make a good contact. Given that, I never accept a connection that has gaping cravasses in the pin/pad connection or doesn’t appear to smoothly connect to the pin. I’m also not happy if it looks like there’s only a thin layer of solder connecting them both, it works for machine soldering, but hand-soldering doesn’t have that level of accuracy.

If you see a potential problem, remember it’s easy to retouch the solder joint and add a tiny amount of solder if there isn’t enough.

Also check that there doesn’t appear to be any connections where there shouldn’t be.

Look for what’s called ‘solder splashes’, random bits of solder splashed across the circuit, they will cause inexplicable problems when checking the PCB... or smoke when you turn it on.

Also, make sure you’ve snipped all the legs from your components to no more than 1 or 2 mm (mine are generally 2mm) from the bottom of the PCB.

Finally, check to see that all the components are in the right places and right orientations (compare with the photo). If You’ve Made a Terrible Mistake and you find some components will have to be removed, you'll need the solder sucker; I’ve provided a link to how to use one.

Testing The Board.

Before powering up the circuit you should check the connections. It’s quite exhaustive. The connections correspond to this circuit layout:

Checking Connections

For testing, I number the pins on components according to the PCB oriented as above:

• • All the simple 2-pin components are numbered with pin 1 on the left (if they’re going horizontally) or pin 1 at the top (if they’re vertical).

  • IC pins are numbered according to standard chip pin numbering: pin 1 is bottom left, then on its right is pin 2 and so on until we get to the right-hand end of the IC; then the pins are numbered from the top, right on the chip going left to the top left pin. So, pin 1 of IC1 is bottom left, pin 7 is bottom right, pin 8 is top right, pin 14 is top, left.

  • Header pins are numbered left to right and the rows are: FIGnitionConn top, PassThruTop, FIGnitionConnBottom, PassThruBottom.

  • The PS/2 Connector is ordered, top to bottom, left to right. Pins 1 .. 3 on the left, Pins 4..7 in the middle and Pins 8 and 9 on the Right.

The connection checks below mean that you start with the component in BOLD and for each of its pins (in the "IC:Pin" column) test to see if it connects to all the pins listed in the other columns on that row. Then go to the next row until you’ve finished checking the component (connections in brackets are reminders about what the connections mean, e.g. (GND) ). Connections in Italics don't strictly need to be tested, you've tested them earlier.

Checking Shorts

It’s just as important to check for shorts - that is, many connections SHOULD NOT connect together. The ones you really need to check are connections next to each other (i.e. U1:1 shouldn’t connect to U1:2. U1:2 shouldn’t connect to U1:3 etc), since this is where you’re likely to have made a mistake.

Check U1’s adjacent connections. No U1 pin should connect to the next one.

Check C1, C1.1 and C1.2 shouldn't connect.

Check PS/2 Conn connections, pin 4 shouldn't connect to pin 5 or pin 8; pin 5 shouldn't connect to 6; pin 7 shouldn't connect to pin 6 or pin 9.

Header connections for every row, no header connection should connect to the next one apart from FIGnition Conn top.8 which should connect to FIGnition Conn top.9.

Testing the Board: The Final Stages

You’re now ready to start testing the board with actual power connected! At this stage, the ICs shouldn’t be inserted. The first test is the non-functioning power on test.

• 1. First check there’s no stray bits of metal under the PCB, nor stuck to the underside of the PCB!

  2. Next connect FIGkeys to the underside of a FIGnition.

  3. Power on the FIGnition by plugging in the USB cable, there should be no pops or smoke and FIGnition should boot normally.

Next we need to remove power from FIGnition and then DISCONNECT FIGnition from FIGkeys before testing with the ATTINY24 inserted.

Inserting The ICs

For some reason manufacturers supply ICs with their pins splayed out, but the sockets need them to be vertical as shown below:

You may find that your ATTINY24 already has it legs straightened out, but if not, you’ll need to bend them. This should be done all at the same time so they stay in line, but they’re fairly fragile, so you need to be careful.

• 1. Hold the chip with one end in a pair of pliers and the other end between your fingers.

  2. Then level the pins against a straight wooden surface for one side.

  3. Then carefully turn the chip around (being careful not to touch the pins themselves with your fingers)

  4. Repeat the process for the other side.

[ Insert diagram of 14-pin chip leg bending]

Now you’re ready to insert the chip.

• 1. Place the PCB on your bench with the front side of the PCB facing you.

  2. Locate the notch on one end of the chip. That’s the end that should point to the top of the PCB (towards the PS/2 Socket).

  3. Use your fingers to hold the chip by its plastic body, at the far ends of its body, whilst avoiding touching the legs as they can be damaged with static electricity.

  4. Carefully insert the chip into its socket WITHOUT bending any of the legs, or twisting them etc. You might need to readjust the legs (using pliers of course), but you must make sure they’re all located well enough before applying force. You’ll need a certain amount of force, but it won't need to be very much by hand. Remember to insert the chip with even force since if one side or end goes in first it may twist or bend the legs of the other end, preventing it from fitting.

Now for a little bit more checking.

• 1. Check the pins have all gone in OK (there’s no metal pins squiffing out of a socket).

  2. Check that the notch on each IC is pointing to the top, which is towards the PS/2 socket (otherwise you’re likely to burn out entire chips as you’ll power FIGkeys using signal pins.

Once you’ve done that you’re ready for the next test:

• 1. Connect FIGkeys to the underside of a FIGnition.

  2. Power on the FIGnition by plugging in its video cable then the USB cable, there should be no pops or smoke and FIGnition should boot normally.

At this stage you won't be able to use the keypad as normal, because FIGkeys will be overriding it. The final test involves using the PS/2 connector.

• 1. Remove the USB-B connector again (you don't need to disconnect FIGkeys)

  2. Connect the PS/2 keyboard.

  3. Repower FIGnition by plugging in its USB cable. FIGnition should boot normally.

Now when, you type on your PS/2 keyboard, the characters should appear on the FIGnition screen :-)

Congratulations, you've built a FIGkeys 1.1 PS/2 Interface :-)