Download Assembly PDF

Your ATMEGA328p will arrive pre-programmed, but you may want to modify or re-upload the software at some point.  You can do that by following the instructions on this page.

If you are looking for assembly instructions for version 1 of the µKenbak-1 (in the 3D printed case), you can find those instructions on this page.


THIS IS IMPORT STUFF, READ BEFORE BUILDING!  Here's where I'll add a few items that did not make it into the manual:

  • Page 9 of the instructions tell you to solder wire from SW16 to the center pin and bottom pin on the switch. You will need a short piece of two conductor wire for this. Don't have any wire? No worries, you can make due with a bent paper clip or almost anything conductive.

Keeping the LEDs Straight

  • To prevent the front panel from bowing, the LEDs must be installed straight. This can be difficult, but I have found a method that works. First, put the LEDs in place (long leads facing to the right.)
  • Next, place the laser-cut spacer in place.
  • Put the front panel in place and secure it with six bolts and the nylon standoffs.
  • Now you can rest the LEDs on your work surface and the front panel will keep them in place while you solder them. Once all LEDs are soldered, you can remove the front panel and spacer and set aside for later.

If you have already soldered the LEDs in place without the above procedure, you can straighten them with the following procedure:

  • When adding the front panel, you may see that is bows a bit, typically on the left side.
  • This can happen when the LEDs are not centered and are leaning to the right and putting pressure on the right side of the cutouts.
  • To fix this problem, grab your heated soldering iron and with your fingertip, push the LED to the left...
  • ...while you reflow the solder on the right leg of the LED. In some instances, you may need to reflow the solder on both legs.
  • When the LEDs are straight, the front panel will sit better. You may also want to loosen the bolts holding the nylon spacers while performing this.
  • When you add the tactile buttons to the circuit board, make sure they are installed flat to the board. It's important that they do not lean to the top/bottom/left/right.
  • If they do happen to lean a bit and you can't desolder them to completely straighten them, you can used a sharp X-Acto knife to trim around the button hole so the push button caps don't bind and so they travel freely. Just be careful so you don't scratch the face plate!

Random Mem Lock problem

  • If you purchased your µKenbak-1 before 8/24/2021 you may have noticed a random issue where you cannot store a value to memory. You can tell if this is happening because the LED above the STOP button will not blink when you press the STORE button. This can happen because there is code on the Atmega328p chip that tries to read a mem-lock switch, which is not present in the µKenbak-1. I have since learned that leaving an input "floating" in an Arduino project is not good.
  • If you're not experiencing this problem, you don't need to do anything. If you are seeing this problem, there are two possible solutions. First, you can upload new code to the Atmega328p. This will require access to an Arduino Uno. The process is outlined on this page.
  • The second solution is to solder a 10k resistor between pin 13 on the Atmega328p and ground, available on pin 8. You may want to snip away part of the acrylic spacer. This keeps MEM LOCK in a permanent "off" condition. If you ordered your kit after 8/23/2021 the code in the Atmega328p has been changed to prevent this behavior.

RTC losing time on power down?

  • I have only heard of one instance where this has happened, but I was able to reproduce the problem and find a solution.

    The problem presented when the power switch was turned off. Upon turning the kit on again, the time was reset to 12:00.

    Adding a .01uF (104) capacitor between the power and ground on the RTC module (as pictured) appears to fix this issue. This fix is not necessary unless you are seeing this behavior.