Blinken Button Kit – How To
Before you start you should check the SMT Soldering Tutorial. But do not be scared – soldering it will be very easy.
If you have any question or do not understand anything just leave a comment to this page and we will try to incorporate the answer in this how to.
Solder the Kit
With your kit you got (from top to bottom and left to right):
- Kingbright TA15-11SRWA Matrix
- CR2032 coin cell holder
- 0,1µF capacitor (C1,C3)
- 220? resistors (R20,R21)
- ATmeag168 CPU
- 1µF capacitor (C2,C4)
- Safety pin
- 56 Ohm resistors (R1 – R8)
- BC859 PNP transistors (T1-T8)
- Green LED (with black marking on packaging)
- Diodes (D1, D2)
- 8MHz resonator
- Power switch
- 10k? resistors (R9 – R19)
- Sockets for ISP and serial port
- Pins as adapters for ISP programmer or FTDI cable
Preparing the board
First of all prepare the board – else you perhaps forget it.
Just put a nice solder bump on the middle pad of the batery holder. If you do not your battery has perhaps no connection and will not power your kit. A small blob will be enough, you just want a little bump. Be sure to apply enough heat so that the solder blob covers the whole middle pad.
Solder the ATmega168
It is so big that you can easily keep it in position with your finger. Be sure that it is aligned correctly. Align the chip so that the dot on the PCB is in the same corner as the dot on the chip. If the PCB texts and the texts on the chip have the same alignment you have done it right.
All pins should sit directly on the pads. Solder one pin first and correct the position, still heating the solder – it must sit perfectly on all pads! After that you can fix the opposite corner (now you cannot correct the position anymore) and solder all pins.
It does not really matter if you bridge some pins (look at the mess in the picture). The solder bridges can be easily removed using solder wick or just scrapping them of with your soldering iron (turned on of course) – if you put it between two pins and move it away from the chip it takes away a bit of solder – an easy way to ensure that all pins are soldered correctly. Triple or better quadruple check it for any solder bridges left – and remove them. In the end it should look like this:
Soldering the capacitors
Soldering the capacitors is very easy: First put a tiny solder blob on one of the pads. Take the capacitor with the tweezers and put it over the pads. While you do it reheat the solder blob so that the capacitor now sticks to on this pad. Now move away the soldering iron and let it cool down. The solder blob should have the size that the parts is just ‘glued’ to the pad. It does not have to be a nice solder connection – even if you have spikes in you solder, since the flux is gone, does not matter – you will reheat it later. Ensure that the capacitor is aligned to the pad and sits flat on the surface of the PCB – if not correct it. Now you can solder the second pad. After that is done reheat the first pad and add the right amount of solder to it (it should form some kind of little slope up to the upper edge of the capacitor. the whole side of the capacitor and the whole pad should be covered by solder.
First solder the capacitors C1 & C2 – both are 1µF ceramic capacitors.
The add C3 and C4 – 0,1µF ceramic capacitors:
Soldering the resonator
Next the resonator – this is the most complex part of the whole board (solderwise). This step is optional. If you do not feel comfortable just leave it out. The resonator is needed for Arduino compatibility.
I managed to solder mine by adding a very small blob on the middle pad of the resonator (bottom left corner of the ATmega168), shift the resonator with my tweezers in place, while still heating the middle pad, positioning it and letting the solder cool down. This left little bit of the pads exposed. Then I added some solder to the left and right pad and made sure that it has flown under the resonator. After that I removed the excessive solder with some solder wick and inspected it. It seems OK – but I still not dare to test it. If you own a hot air rework station it is much easier (but I wanted to do it with the tools I suggested).
Next solder in the sockets for the ISP and serial connection.
Next move on to the power switch. It is quite easy to solder, but take care that the pins on the bottom of the solder are really placed in the holes – else you will get problems when adding the display. Adding a littl bit of solder on the tip of the iron, shifting the power switch in one place and fixing one pin should do the trick. after that you can solder the remaining pins.
For some extra strength you can solder the front pins of the switch in place. Be sure to add a lot of heat to the switch, so that the solder flows nicely. It sounds more complicated than it is. Heat the pins, add the solder and check on the bottom if it has flown through the hole. If not reheat the pin and perhaps add a bit more solder. Rinse and repeat.
Now finish the bottom of the board – since nearly all is needed for the first test and it are not so much parts anyway. Start with the battery holder. This is really easy. The best way I found is adding a bit of solder to the pads, heat them well so that they are covered completely. Align the battery holder and reheat one pad (use your tweezers, the battery holder can get real hot) and press the battery holder down, make sure that it gets a good connection with the solder, the excessive solder should flow through the hole in the pad of the battery holder. Repeat that for the second pad. Then add enough solder so that both pads of the battery holder are well covered. This step will take a lot of heat and patience, so add it.
Next move on to the LEDs.
It does not matter which LED is used for programming and which for power. Your kit contains a green LED (with a black marking on the packaging) and a orange LED. The orange LED will be brighter than the green one. I suggest using the green one for power. But that is up to you.
The LEDs have some marking on the button which must align with the markings on the PCB. The markings on the PCB are a bit hard to spot. But there are three black dots closer to one pad than the other. The lower part of the ‘T’ on the diodes must face into the direction of the pad with the dots. Perhaps it is easier to see which pad goes to the groud plane. This pad has 4 connections to the ground plane. It is best to see the correct alignment in a picture:
Soldering is again the same, well known procedure as with the capacitors.
Soldering the resistors
Next add the LED series resistors R20 and R21, these are the 220 Ohms resistors, marked with 2200. They are soldered the same way as the capacitors:
Next add R17, a 10k Ohms resistors, marked with 1002.
Now you are ready for the first system test.
First System Test
Now it is the first time to power on your Space Invaders Button. Put in the battery, connect the ISP programmer (most probably you will need the pin headers as adapters).
Switch on the button (with the switch – if the PWR LED is already glowing the button is already on – do not switch it off). Now you should be able to read the fuses of the ATmega or program it. If this works well: Gratulation, you have finished successfully the first system test. If it does not work, relax and check all solder connections again.
Finish the Kit
If you have put in a battery take it out again. Now you can put in the rest of the resistors and the transistors on the front side. You should begin in the middle and go on to the outer parts of the board.
Remember that the resistors R1- R8 are 56 Ohm marked as 56R0, R9-R17 are 10K Ohms marked 1002. The transistors are soldered the same way as the other parts – just on pad more. If the transistor is a bit misaligned you can bend it a bit (up to 5°-10°, but positively not more).
If you want to speed things up a bit you can add a solder blob to one pin of each component.
Solder the components using the solder blob.
And then finish them all up.
Soldering the diodes.
They have little white (or to be more correct slightly less black, click on the image to see it better) bars on one side. They must face towards the markings on the PCB.
After you have finished everything it is time for the …
Final System Test
Put in the battery, connect the ISP and load firmware on the system. The source code can be found over at github. For any questions remarks regarding the source code, just leave a issue there and we will take care of it. The easiest way is to create a eclipse project for it. For testing enable the
TEST_MODE setting, which can be found in
The source code unfortunately does not include the configuration for the fuses (yet). The fuse configuration is quite simple: Enable the internal 8Mhz oscilator and disable the clock divider, which is enabled by default. My Eclipse IDE tells me it uses the following fuses: Low: E2, High: DF Ext. 01.
Alternatively you can use the 8 Mhz resonator (if you managed to get it on the board. But be warned. If it does not work you cannot reprogramm the chip without an high voltage programmer. This will be verified in the near future.
After this is done and before soldering on the display you should check every pad if it gets a proper signal. Best way to do it is to inspect every pad with an oscilloscope.
Poor Mans Oscilloscope
If you do not own an oscilloscope you can create one yourself: Just solder some wires to a LED, connect the anode or cathode to every pad (connecting the other pin of the LED to GND or Vcc. On the positive pads it should glow dim, on the other pads lighter (or the other way round – I will check this – but the principle should be clear – you simulate the LEDs of the display).
If you look at the board the square pin is pin 1. The pins are counted from 1 to 8 in the bottom row, left to right. The top row is counted from right to left and contains the pins 9 to 16. Anodes (+) are the pins 3, 4 , 6, 10, 11, 13, 15, 16. Cathodes (-) are pins 1, 2, 5, 7, 8, 9, 12, 14. If you enable the TEST_MODE on the source code a simple pattern is displayed. If you put the led with the anode on any of the anodes and the cathode on any of the cathodes it should blink in any combination.
If everything is OK you can solder on the display.
Soldering the Display
The display should be aligned so that the bottom (with the text) is aligned to the bottom of the PCB.
Put the display in the PC and tourn the button around. Now just fix the four outer pins with a tiny bit of solder. Ensure that the PCB is aligned firmly on the PCB.
Now clip of the leads directly over the PCB. This is especially important on the botttom, where the battery is inserted. Get sure that it is flat enough to slide in the battery.
Now solder the pins of the display.
Congratulation you just finished your Blinken Button.