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:

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.

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.

[ Insert diagram of 14-pin chip leg bending]

Now you’re ready to insert the chip.

Now for a little bit more checking.

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

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.

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 :-)