First Prototype Fail

Published on 2024-10-14 in BlueJoy.

I rushed the design of the PCB for the first prototype, because I thought that with just three components there isn’t that much I can get wrong at the first try, is it? Well, turns out that I should have read the datasheet for that esp32 module more carefully. Specifically this part:

You will note, that this example schematic contains a crystal. I assumed that a ready to use module would already contain a crystal under the shield, after all it’s one of those things you pretty much always need, and it needs some fine tuning to get perfectly right. But turns out that no, this particular module requires an external crystal. And of course the way all the pads are under the module, I can’t even bodge one in there and see if it will work. I need a second PCB prototype.

So I sat down and redesigned the board a little bit. I used smaller resistors, and moved the programming header a little bit to the edge, to make room for the extra components. Apart from the crystal with its capacitors, I also added two extra resistors, just in case: one pulls the RST pin up, and one pulls the IO12 pin down. Since I don’t have the required crystal and capacitors at hand, I decided to get the boards assembled this time — that way I don’t have to pay for the shipping of the parts, and since all the parts are from the basic parts set, the assembly is almost covered by the coupon. The module itself is not included in the assembly, I will have to add it myself.

I still felt bad for wasting money on a bad prototype, though, so I picked the cheapest shipping option. I will work on some other projects in the mean time.