Hey fellow nerds!

I had a weird issue I could not understand. Here’s how it went down.

When I got the new PokyPow from Soldered, I had to adjust the code a bit, since we now have sensors for button presses on the PC case side. Then we evaluated if we have the child lock active. If not, then we short the power and reset button on the motherboard to turn on/off or reset the PC.

So far, so good. It worked on my gaming PC. However, connecting it to a different mainboard was not working. So I started by connecting one cable after the other. Connecting everything except the power and reset button on the mainboard side, the board was working fine.

But, as soon as I connected the power or reset button to the PokyPow, the PokyPow would just shut down.

I called my friend and hardware engineer Niklas. He has the knowledge and the equipment at home to debug these issues. I just have a multimeter and a basic understanding of electronics.

Why the Shutdown?

It looks like the one random mainboard I had lying around saved my bacon. There was a current backflow of 40 mA from the power button. We think that led the ESP32 to go into a failsafe mode: "Nah, man, this is too much. Gonna shutdown!"

By putting a diode in the circuit, we prevented the current backflow and the PokyPow stopped shutting down when connecting the power and reset button from the mainboard.

Still, when triggering the button via the web interface, the mainboard did not turn on.

Why Doesn’t the Power Trigger turn the Mainboard On/Off?

We checked the voltage on the power pins of my mainboards. The one that worked had perfect 3.3V. The one that did not work had 3.7 V, which is more than the ESP32C3 can provide. It also looks like the mainboard expected this voltage and 3.3 V was just not enough.

Solution

When I got the board, the Soldered team suggested a change: switch from MOSFETs back to optocouplers again. That change would allow the use of an external power supply. With MOSFETs, you can only use the PokyPow as long as it is plugged into the same PC.

Luckily, the optocouplers are the solution for the other problems we discovered as well (current backflow, voltage too low). So we are going back to optocouplers.

Minor Issues

There were also some minor things:

• Wrong labeling on the backside of the board
• A male instead of a female USB 2.0 connector
• ESPHome did throw a warning about using a strapping pin. Since we have two pins left, we are moving to another pin. That way, people will not be confused when they compile the firmware themself.

Where Are We With the Campaign?

We are working to get the final board layout and bill of materials (BOM) ready. With that final part list and board, we can ask Soldered what 50, 100 or 200 boards would cost in manufacturing. There are different scaling effects that impact the price per unit. The price per unit is very important in order to calculate the selling price for each board. It includes the cost of the board itself, credit card fees, the Crowd Supply fees, shipping, taxes, and more. With all those values I can determine a campaign goal and propose that to Crowd Supply.

We’ve already paid for the next prototype. Let’s hope it comes soon!

That is it for now.

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Enjoy your day!