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Comment by fellerts | Hacker News Reader

So apparently the Pinecil is a BLE-enabled soldering iron with a 108 MHz RISC-V processor running a custom real-time operating system [0]. The author wanted to access the UART logs, so they repurposed a Raspberry Pi Pico (a dual-core microcontroller system running a real-time OS) for the task.

That's a staggering amount of hardware, sortware and computing power devoted to decoding one of the simplest and oldest serial protocols from a device whose sole purpose is to essentially melt tin. Maybe I'm out of touch, but I think I'll stick to my thermostat-controlled Weller soldering station and FTDI UART converters. I apologize if this post comes across as snarky, my point is that these are solved problems and have been for half a century.

[0] https://github.com/Ralim/IronOS

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Well, it's all solved problems, but the cheapest temp controlled Weller is over USD 200, and the Pinecil is 25.

The almost ubiquitous accessibility of cheap miniature general purpose microcontrollers/CPUs allows easy and fast creation of a device like the Pinecil, with a miriad of features: programmable PID, motion sensor, Bluetooth controller, temp profiles, battery powering, calibration, easy access to code... Cheap and fast. And it feels durable, not a toy.

And, if you don't have a FTDI UART converter or a logic analizer around, you just take an RP2040 from your electronic parts bin, and reprogram it. And once you finish, you can reprogram it for a different thing.

To be fair, everyone who is into MCUs has a USB serial converter lying around, if not several. Or more snarky: repurposing a RP2040 is only free if your time has no value.

I really hate this argument about how your time has no value if you do something that others may consider "Solved problems.", "Boring thing to work on." or whatever argument people can come up with.

God, this is a website full of "Hackers" and all 90% of the users can think of is how to get the most money out of the things they do.

Yeah, I hate this. My time has tons of value when I do stuff I don't want to do. Hacking RP2040s into a UART controller so I can talk to my soldering iron? I'd pay for that.

I agree. If you're enjoying your time it has value.

> To be fair, everyone who is into MCUs has a USB serial converter lying around, if not several.

I can understand why you would think that, but I can also tell you that I didn't buy a serial connector until years after I started playing with microcontrollers.

I've never used a stand-alone one.

I've got Arduino sketches I can quickly flash onto an Uno (or my 2016 HiFive1 320 MHz RISC-V board, which is usually closer to hand) to do all manner of things including UART, flashing a bare AVR chip e.g. ATTiny85 (now supplanted by CH32V003) and so forth.

Same principle as using a Pico.

Well, I used to have one or two around while doing smaller MCUs years ago, but I stopped using them once all the smaller esp8266 and esp32 started coming with one included in the board, but yes, it's not unusual. The difficult part is finding them after years of not using them ;-)

Running the Embassy RP2040 USB CDC ACM serial example takes about 5 seconds on a Pico.

https://github.com/embassy-rs/embassy/blob/main/examples/rp/...

> Maybe I'm out of touch, but I think I'll stick to my thermostat-controlled Weller soldering station and FTDI UART converters.

Regarding FTDI products, after the well known controversy (1) I avoid them as much as I can. I also have two Wellers and will keep them until they die, which given their reliability should equal to never, but a few years back I purchased a Pinecil (1st model) out of curiosity and because I wanted to support Pine64 some way, and have to admit the device works really well even with non trivial joints that require a decent thermal mass (something many of those Hakko clones fail at). I have never installed anything onto it or even used any other function than plain temperature control though, but as a portable solder iron it just does the job without hitches.

1- https://www.reddit.com/r/amateurradio/comments/43q3vt/ftdi_d...

I carried a butane torch soldering iron for years before the pinecil. I wasn't expecting it to have nearly the capacity but I've soldered some 8ga with it.

You're missing out, pinecil is the best soldering iron I've ever used. I really like that it automatically turns off based on the accelerometer input when you set it down

FTDI chips cost at least $5 (https://www.findchips.com/search/ft232), but an RP2040 can be bought for less than $1, so it makes sense to use an RP2040.

Repurposing is also great. I have FTDI UART adapters that I've used once five years ago, and couldn't find them later, then had to buy another new one for using it (again) just once.

If I can take one of my rp2040s and use it for half and hour and then use it for a different thing, it's great

RP2040 is so cheap it is used in the debugger for the Pi Pico.

https://www.raspberrypi.com/documentation/microcontrollers/d...

WCH CH340 USB-UARTs cost less than an RP2040 (and probably the external flash.)

https://www.lcsc.com/search?q=CH340

The reason to use an RP2040 is that you need a little bit of logic with that UART.

Doesn't the RP2040 require external qspi flash? What does that cost?

MCP2200 is ~$2.50 in single units and you don't have to deal with firmware or programming.

There's other FTDI chips than the FT232, the FT230 can be found for <$2.

Its overkill but the BOM is probably a lot cheaper than whatever is running my Metcal station.

I just switched from an old analog Weller to the Pinecel and I have to say it was a wonderful upgrade. The weller was retired to just do heat-set insert nuts, while I use the pinecel probably an hour or more a day, in short bursts. The fast heating ends up being very useful, and it just works, like the Weller just works. I don't modify any settings or talk to the processor.

> I'll stick to my thermostat-controlled Weller soldering station and FTDI UART converters

How do you use an FTDI adapter to read from a Weller thermostat? What MCU is the thermostat?

The thermostat is analog and dumb, no code involved. I don’t want my soldering station to run an OS, and I don’t want to program a Raspberry Pi when I need to interact with something over UART. In my mind, these tools are a means to an end, but I understand that people enjoy hacking on them.

> The thermostat is analog and dumb, no code involved.

I'm not certain about how dumb something is if no code is involved. Just might be very smart to be able to leverage fundamental physics in such a way.

That said, analog processing can be subtle. Have you disassembled the thermostat to see how it implements PID?

I mean “dumb” in the sense that a non-smart TV is dumb compared to its modern counterparts, not that it’s stupid or poorly designed. IMO, dumb systems are often preferable. Less magic that can suddenly break on you.

Also, the Weller in question (WECP 20) isn’t doing PID. There is a potentiometer knob and a resistive temperature sensing element in the iron that together either turn heating on or off. It doesn’t get much simpler than that. Full schematics are readily available online.

Wait, so it uses a continuous range of voltages instead of PWM to control the heating element? Do tips not have an ideal voltage for efficiently emitting IR?

> Wait, so it uses a continuous range of voltages instead of PWM to control the heating element?

Heating is either on or of, but it's on the order of "a few times per second". The heating action is connected to a small indicator lamp that lights up when the transformer is pushing power through the iron. You can hear the transformer buzzing briefly every few seconds to keep the tip around the set temperature. Touch the tip to a large thermal mass, and the transformer buzzes continuously. I expect there is a Schmitt trigger or a simple comparator in the control board that is in charge of the heating action. Again, check out the schematics to see how simple it is.

> Do tips not have an ideal voltage for efficiently emitting IR?

What do you mean by emitting IR? A soldering iron doesn't melt tin by radiative heating. You make physical contact with whatever you are intending to heat.

Are you perhaps thinking of Curie point soldering (or inductive heating) [0]? Those employ a much more complex process. My Weller goes by the "make the pointy metal stick reasonably hot" principle.

[0] https://www.metcal.com/wp-content/uploads/2021/11/how-it-wor...

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