Assembly Instructions

The TWI 7-segment Display comes partially assembled: The main processor and auxilliary components are all soldered on, but the headers and actual display must be soldered on by the user.


To assemble this kit, you will need:

  • A soldering iron
  • Solder
  • A wire cutter (a diagonal type that allows you to cut the wires as close to the soldering points as possible is best)
  • Helping hands or clips to hold the PCB in place when soldering (a vise will also work)


  • A multimeter
  • Desoldering wick
  • Solder sucker
  • Protective glasses

See the equipment page for more details.

Step 1

Top side: (this is where the 4-pin headers go)

Bottom side: (this is where the display is inserted)

Start by inserting the two headers. They go on the top side as shown in the picture above (the side the processor is on). Place the female header on the left side (it will stick out a bit). It is neccesary to hold it in place before turning the board over to solder it. The easiest is to use clips or helping hands, but in a pinch a strip of masking tape will work as well.

Make sure the header is aligned properly (and not angled in relation to the board), then flip the board and solder one point. Check that the orientation is ok. If not, re-heat the solder point and adjust the aligment of the header. When you are happy with the alignment, solder the remaining three pins.

Repeat the same procedure for the male header, which goes on the right hand side.

<%= make_note( "If you only intend to use one display, you can skip adding the male header on the right side: This header allows you to daisy-chain several displays (making a 8-digit or even a 12-digit display), so skip it only if you intend to only use one display. The solder-points for the headers will be obscured by the display, so it is not possible to add in the headers later on if you change your mind.

It is also possible to put the male header on the left and the female header on the right, just make to assemble all your displays in the same way if you have more than one, otherwise it will not be possible to daisy chain them without using extra cables." ) %>

Step 2

Now it is time to place the display. It should be inserted on the bottom side of the PCB:

Take a look at the pins of the display, you will notice that there is a small number 1 printed near one of the pins. This is pin #1, and it should go into the pin marked with a 1 on the PCB. It is very important that the alignment is proper: If you put the display upside-down it will not work, and it is very difficult to undo.

<%= make_note( "If you ever want to reprogram the firmware of the display, you can do so using the 6-pin ISP header. You will need to solder 2x3 pin female header (not included). The header can be soldered even after attaching the display, but it is quite close, so be sure not to burn the plastic." ) %>

Carefully push all the pins through the PCB, and turn it over so that the pins point upward:

Press the PCB down so that it sits flush against the display. Solder one pin on each side first, and check to see that the aligment of the display is good. Once you are happy with the alignment, solder the remaining pins.

Step 3

Finally, cut off the excess part of the display legs. Cut each leg close to the solder point.

When cutting the legs, they may come flying towards you at high speed, so be sure to wear protective glasses. It is also possible to hold the leg you are about to cut with pinchers to prevent it from flying.

Congratulations! The display is now fully assembled and ready for use.

Head on to the null for further instructions!