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Comment by konschubert | Hacker News Reader

I am sure this is something will be able to answer:

I need to build a custom board for an ESP32 which should support low-power deep sleep and which should contain some additional circuitry (is that what you call it?) to drive an Eink display.

Basically this[1] board, but a different shape and better low-power sleep properties.

If I wanted to design this board myself, how long would it take to learn this? Are there good resources?

If I were to pay somebody to do design this, what order of magnitude would the cost be in?

> https://eckstein-shop.de/Waveshare-Universal-e-Paper-Raw-Pan...

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Have you already made the circuit on a breadboard? If so, learning KiCAD and building the board from scratch would take around a week of afternoons.

I really recommend it, designing PCBs is very enjoyable (at least to me).

How would I work with SMD components on a breadboard?

Breakout boards, I assume.

Either breakout boards or you use the through-hole versions.

If you're confident in your design, you can send it off for assembly at a manufacturer that does PCBA. They'll handle the SMD soldering for you.

Thank you for mentioning KiCAD, these are the kind of keywords that will help me get started :D

PS: And yes, while I really suck at soldering, working with physical products feels like a nice counter weight to the software world.

KiCAD is amazing, and it's all you'll need (apart from the prototype on the breadboard).

The trick to soldering is really to get a good iron, I underestimated it at the start but you really need something that keeps heat. Get a TS100 and set it to 320, soldering is going to be a breeze afterwards.

Remember, solder should flow easily and stick to the pads/wires, if it doesn't, it means you need to heat the thing up a bit more.

I my iron shoes 400 degrees in the display but somehow the pads/wires don’t heat enough to melt the solder.

It’s really weird. Maybe I messed up the tip somehow? But I just got it a few days ago!

Which iron is it? Maybe it's miscalibrated? Does the solder melt if you touch it to the tip?

It melts. But only at high temperatures above 300. Even though the soldier is supposed to melt at 219.

The iron is a LONOVE 925 m.

Maybe I need to try tinning the tip again.

Yeah, sounds like it. Make sure the tip is tinned when touching the pads so heat transfer can occur more effectively.

I’ll need to watch some videos. I tried running but the solder always drips off the tip and doesn’t stick ️

Hmm, sounds like you need more heat, hot solder likes to run up metal surfaces and stick well.

If you are comfortable prototyping on a breadboard it shouldn't take long to produce the layout in KiCAD or a similar EDA tool.

Then you can order your PCB at a local shop, manufacture it yourself (with toner transfer, a CNC at a hackerspace, etc) provided the traces aren't too thin and there are not too many layers (1 is easy, 2 is standard and cheap, more layers are expensive), or order it from china at a relatively low price (jlpcb or seedstudio will average something like $1/apiece).

>If I wanted to design this board myself, how long would it take to learn this? Are there good resources?

To learn it yourself, assuming no prior experience or knowledge, would take years of full-time study.

We’re talking low speed data lines and run of the mill digital circuits, not 10GHz range RF amplifier design. A month is probably enough.

Okay, so now I know it’ll take between 5 years and one month :D

On the one hand, I have a bit of prior knowledge. On the other hand, I want a circuit with minimal power draw in ESP32 sleep mode and i’m afraid that does require some experience.

Does it have to be an ESP?

There are other microcontrollers capable of driving an eink display that consume a lot less power out-of-the-box. Eg: atmega328 (~5 μA deep sleep, ~10mA running)

If you want wifi, then ESP is probably a good and cheap fit. A wemos d1 in deep sleep doesn't consume _that_ much power (~80 μA), unfortunately it does draw a lot when booting (~200mA).

Yes, I need wifi. And there are esp32 boards that draw 20uA in deep sleep.

Just a heads up, there's been a fair number of bugs and issues around sleep mode. Most of the problem seems to be in software and the situation has improved, but you might want to look into the exact state of things.

I'm working on an ESP32-based product that doesn't use sleep mode, but I've noticed people reporting issues about sleep mode on GitHub and in forums.

I assumed zero prior knowledge. I'm a pretty smart guy but I don't think I could go from zero to "designing an esp8266-compatible board that includes an e-ink display" in a month.

A good place to start would be reference schematics from Espressif for their dev boards, and schematics from open ESP32-based boards from other vendors. Check out esp32.com for a list of boards.

With those schematics and KiCAD, you should be pretty much set. Take an hour or so watching KiCAD tutorials, it'll be worth it.

Also, spring for an ESP32-WROVER-KIT and use it to prototype with a dev board. That kit also supports JTAG debugging, which can be quite handy.

Thank you, this is really helpful.

Sure thing. By the way, I should have said esp32.net, not esp32.com. The latter is the official discussion board, but the former is an unofficial reference site that's incredibly useful.

I have used TTGO ESP32 2.9" e-Paper. For my projects it contains all what I need.

I recommend you to check that out.

Paying someone to do it is probably 200$ to 300$ on Fiverr.

I just got an Inkplate 6 and it seems pretty cool: inkplate.io.

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