undefined | Better HN

0 pointsTaylorAlexander2y ago0 comments

Just a note on soldering: I’m perfectly capable of soldering VQFN at home, but these days it’s so easy to order fully assembled boards from JLCPCB that I think lost hobbyists would start with the Pico and then go straight to turnkey assembly once they have a custom design. I stopped assembling my own boards two years ago (after a decade) once I placed my first turnkey order at JLCPCB. Ten pieces of a simple RP2040 board including shipping is like $80.

I agree the lack of floating point and the poor ADC are an issue. I designed a high power brushless motor controller using the RP2040 and the FOC loop only runs at 8kHz which is fast enough for my use, but much slower than a higher end board. I just love this processor too much to use something else.

The main advantage to this processor is that it seemingly will never go out of stock (until it’s EOL date). When I started designing the motor controller in early 2022 during the chip shortage, I went to the Digikey “microcontroller” category with no filters and sorted by most in stock. They had millions of RP2040’s - it was the most in stock microcontroller on Digikey. I guess since Raspberry Pi only have a single SKU for their microcontrollers they can just churn them out in huge quantities.

My goal is to stay invested in this product line until an updated rev comes out with a better ADC and floating point. I bet they’re working on it.

0 comments

dragontamer2y ago

Hmm.

You have a point about RP2040 being a thing that JLCPCB's assembly service benefits from. A singular chip that you "plan to use in most projects", along with pre-loaded pick-and-place machines that have common I2C attachments, makes sense in the scheme of factory design. (While something like Microchip's AVR DA vs AVR DB vs AVR DD vs AVR EA loses out, because SKUs are the enemy of such an assembly line as you'd be forced to manually swap-out reels in between production runs).

Still, RP2040 is a compromised part with plenty of downsides that I've listed above. And as far as a "centerpiece jack-of-all-trades" microcontroller goes, I'm not convinced that the RP2040 is the best to keep preloaded in such a configuration yet anyway to be mass produced into many designs.

But your point stands. It is a production / prototyping issue that intrigues me and I wasn't thinking about earlier.

------------

> Just a note on soldering: I’m perfectly capable of soldering VQFN at home

Well yes. I did say that Hotplate + Reflow Hot Air Gun works. But *soldering iron* is an advantage IMO.

Personally speaking, I don't see any of the chips I use on a regular basis on JLCPCB's list, so I've never felt the need to experiment with it. I can see how its advantageous if those preloaded pick-and-place machines have the chips / components you use though.

TaylorAlexanderOP2y ago

Sure I agree with all that.

I’ve moved to a model of only designing with parts available at JLCPCB (or LCSC, which you can have JLC order internally for you). It requires a change in mindset, but being able to spend $300 on QTY 10 fully assembled complex PCBAs delivered in two weeks is a revelation. No more boxes of components sitting around my lab. No more hours spent doing microscope and tweezer placement. No more orders split across Digikey and Mouser. I order the PCB and everything else from the same place. Hell I got my first CNC machined parts from JLCPCB recently and their quote was 20% cheaper than the other Chinese CNC house I was using.

It’s real nice. I focus on design and testing and not doing assembly.

GeorgeTirebiter2y ago

Actually, they did a huge buy of RP2040 right out of the chute, in order to get decent prices. Heck, in not huge quantities, the chip costs $ 0.70 --- not so bad.

But if you want super cheap, 'standard'-type uC chip, look at the $ 0.10 https://github.com/openwch/ch32v003/tree/main

j / k navigate · click thread line to collapse