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I like the RP2040

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Re: I like the RP2040

#131

Post by riskable »

jcalvinowens wrote: post #44

The lack of built-in flash kills it for me. STM32 M3s with comparable throughput are cheaper and don't require an external flash chip (example: STM32F103C8T6 for $1.20 from jlc). I love the generic PIO though, I really hope other manufacturers pick up on that.

I used to have the same beliefs but the flexibility of being able to use just about any pin for any purpose really sold me on the RP2040. When I decide to add a new feature to my boards I don't have to spend an hour examining the minutiae of the data sheet to see if I can use a given pin for SPI (oops: no, I can't because I enabled alternate function 3...). It saves a TON of track routing time and simplifies boards considerably.

Once I decided to start using the RP2040 I realized the "strange" flash situation turned into a feature, not a drawback! With STM32 you pick your part and then you can order an expensive version (if it's available!) with the max RAM of say, 512Kb or you can save a few bucks and go with say, 64Kb. Either way you're paying like $2.50-4 for a single chip.

Now compare that with the super fast, dual-core RP2040 which costs $1 (yeah it's technically $0.70 in bulk) paired with a 16 FUCKING MEGABYTE SPI flash chip (W25Q128JVSIQ, basic part at JLCPCB :thumbsup:) that costs $0.60. You get a vastly more capable MCU with so much goddamned flash space you could fit a truck in there!

You can even partition that flash chip's space so that your RP2040 firmware is reserved to the say, the first 2MB (or wherever you wish!) and the rest can be used for storing stuff like settings. It eliminates the need for an EEPROM! Not to mention there's enough storage space in there to store all your settings in something absurdly inefficient like JSON and the chip is fast enough to parse it too!

Working with the RP2040 in reality is just SO NICE. Seriously, try it! You won't be disappointed.

Re: I like the RP2040

#132

Post by dgacmu »

jsheard wrote: post #22
MegaDeKay wrote: post #17

The PIO's really are the star of the RP2040 show, giving it a capability that competing chips like the ESP32 can't match. They are appearing all over the place in the console hacking space for this reason. Lower power consumption in steep modes for battery-backed applications would be a welcome addition in any V2 version though.

Things like battery life will probably improve with experience, I was talking to a silicon guy about the RP2040 and they said it's pretty characteristic of a first generation design. The digital logic that can be validated on an FPGA is fine for the most part, but the analog elements are much more difficult to fine tune, hence the poor power consumption, poor ADCs, and lack of internal DACs or opamps in the RP2040, a…

Though it's a continuing puzzle to me why ESPs have worse ADCs than the rp2040, given their relative maturity. (Neither is particularly good, mind you, but I'm generally ok with the rp for my toy applications.)

Re: I like the RP2040

#133

Post by geerlingguy »

peteforde wrote: post #120

I also like the RP2040, but I'd like to explain why I migrated away from it for my current project. First, the drama with PlatformIO really rubbed me the wrong way. I'm taking the side of the developers who are hurt by confusion in tooling. Second, the top of the line ESP32-S3 comes in a module format that can be dropped on a PCB with basically nothing but a few decoupling capacitors. The RP2040 requires careful plac…

It seems like Espressif are in the same situation as Pi w/r/t PlatformIO[1]. As an outsider, it sounds like PlatformIO was trying to extract a very large annual payment from RPi and Espressif, and that was after the initial support was added in, and some of the community started adopting it.

It's a weird situation, but I think PlatformIO built up a dominant position by supporting all these platforms and accepting community contributions to do so, then tried extracting value from the manufacturers directly after the fact, blocking further community PRs that would add new board revisions or fix bugs. See related: [2]

[1] https://github.com/platformio/platform-espressif32/issues/12...

[2] https://github.com/platformio/platform-raspberrypi/pull/36

Re: I like the RP2040

#134

Post by HyulianGrader »

krisoft wrote: post #125
HyulianGrader wrote: post #105

Earlier quoted context omitted.

No, that's both "just the chip", the chips have different peripherals. They both have the usual SPI, I2C, UART, ADC, etc., and they have their differences too. I could just as well say "For an RP2040 to do USB you wire the RP2040 to the connector. For an ESP32 to do USB you wire the 32 to another chip, and that other chip to a connector." It's clear to me GP has the impression that ESP32 is something more (a developm…

Maybe look at the ESP32 chip's datasheet? [1] This is the first sentence in it: "ESP32 is a single 2.4 GHz Wi-Fi-and-Bluetooth combo chip designed with the TSMC low-power 40 nm technology." That's the chip. Not the development board. 1: https://www.espressif.com/sites/default/files/documentation/...

What part of that contradicts my comment?

To be clear, GP is the one saying the ESP32 is more than just the chip itself, complete with battery controller and camera connector.

Re: I like the RP2040

#135

Post by Aurornis »

moefh wrote: post #114
sophacles wrote: post #98

Earlier quoted context omitted.

So is GP. The silicon chip itself for an ESP has: bluetooth, ethernet, wifi, SD/EMMC, and a bunch more "peripherals" built into it. The RP2040 does not. To make this painfully clear: For an esp32 to do wifi you wire the esp32 to an antenna. For an RP2040 to do wifi you wire the 2040 to another chip, and that other chip to an antenna. Do you see the difference?

GP is clearly talking about ESP32 boards, not the chip; they mentioned "LI Battery Controller", and "Display or Camera Connector". People sell RP2040 boards with those too, for example: - board with a battery charger: https://learn.adafruit.com/adafruit-feather-rp2040-pico/powe... - board with camera: https://www.waveshare.com/pico-cam-a.htm

ESP32 is available as a tiny module that is soldered to the board as if it was a chip.

Ignoring the module results in a flawed comparison. The module is chip and frequently used.

If they encased the module in plastic and called it a chip, it would be the same. You can think of it as a chip.

Re: I like the RP2040

#136

Post by Aurornis »

krisoft wrote: post #125
HyulianGrader wrote: post #105

Earlier quoted context omitted.

No, that's both "just the chip", the chips have different peripherals. They both have the usual SPI, I2C, UART, ADC, etc., and they have their differences too. I could just as well say "For an RP2040 to do USB you wire the RP2040 to the connector. For an ESP32 to do USB you wire the 32 to another chip, and that other chip to a connector." It's clear to me GP has the impression that ESP32 is something more (a developm…

Maybe look at the ESP32 chip's datasheet? [1] This is the first sentence in it: "ESP32 is a single 2.4 GHz Wi-Fi-and-Bluetooth combo chip designed with the TSMC low-power 40 nm technology." That's the chip. Not the development board. 1: https://www.espressif.com/sites/default/files/documentation/...

The Espressif chips are available as cheap modules, and frequently used as such.

People generally refer to the module, not the isolated chip. The modules are effectively like a chip that you solder to the board.

Re: I like the RP2040

#137

Post by dragontamer »

floxy wrote: post #107
Havoc wrote: post #18

How are people using this in practice? I’ve never worked with a BGA device. I’m guessing you need to design a board send it to say pcbway and then have the equipment to solder the bga in?

You would probably be surprised what you can do with a $65 hot plate [0], no-refrigeration-required solder paste[1] and the matching laser-cut solder stencil[2]. [0] -- https://www.amazon.com/Soiiw-Microcomputer-Soldering-Preheat... [1] -- https://www.chipquik.com/store/index.php?cPath=470&osCsid=8t... [2] -- https://www.pololu.com/product/446/

Pololu's stencils leave much to be desired. They do work but I feel like https://www.oshstencils.com/ makes a higher quality stencil instead at similar prices.

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Note that BGA chips mostly come pre-soldered / solder balls. You also design PCBs so that there is a "well" for the balls to melt into and settle into place, and molten-solder has a significant amount of surface tension, so you can magically watch the solder "pull" your designs into place. Of course, the OP is likely talking about QFN not BGA, but... just in case people are worried about BGAs its not terrible... (its just impossible to inspect a BGA XRays).

The surface-tension can be harmful in the case of tombstoning (ex: a resistor or capacitor with two leads, especially a "sideways" low-inductance capacitor, will get "pulled up" by one side, lifting off the 2nd pad).

If you have a solder-plate + hot-gun, you can "feel" the surface tension by just grabbing a toothpick and pushing on these components as they're still hot. You'll find the pressure to be far higher than you expect.

Re: I like the RP2040

#138

Post by dragontamer »

Havoc wrote: post #18

How are people using this in practice? I’ve never worked with a BGA device. I’m guessing you need to design a board send it to say pcbway and then have the equipment to solder the bga in?

RP2040 is QFN, not BGA.

QFN is doable at home, though more difficult than TQFP leads or larger SOIC-chips. Still, far too many components are QFN today so its a good skill to pickup.

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The techninque is:

1. Reflow soldering brings the _whole_ board to soldering temperatures, and then relies upon surface-tension to pull all the devices into proper place.

2. Solder paste is applies ahead of time. You can cleanup solder paste with a toothpick before you bring the board up to temperature. Solder paste tends to go bad pretty quickly however. When doing prototypes, opt for the more expensive low-melt solder paste to minimize potential heat damage.

3. Prefer to use a stencil to apply solder paste. But its more than doable to be sloppy with a syringe and then rely upon the solder mask + surface tension to magically cleanup things during reflow temperatures.

4. Use a hot-air gun to fix any issues. The #1 issue you'll have is tombstoning, QFNs or TQFP chips are usually pretty good about settling into place. For TQFP issues (ex: bridging), you'll need solder-wick + soldering iron. EDIT: And flux: lots of flux helps. Also, flux goes bad, so throw away Flux all the time and keep buying new batches.

---------

BGA is also doable at home btw, thanks to the above principles. But its even harder than QFN. The real issue of BGAs is that you're looking at 4-layer minimum, maybe 6, 8, or 10-layer designs. There's also substantial grounding and other advanced PCB concepts you need before you can layout a BGA-capable PCB.

Its not so much the physical activity of soldering that's hard or difficult for BGAs. Its all the theory you need to study to breakout BGAs + minimize inductance + deal with impedance matching and trace-length matching.

Re: I like the RP2040

#139

Post by dgacmu »

moffkalast wrote: post #122
nickcw wrote: post #31

If you are an electronics hobbyist but don't want to make/design your own surface mount boards (like me) there are lots of very accessible RP2040 boards at very low prices. I've used it in the Raspbery Pi Pico ($5) which comes on a nice board with lots of IO. There is a W version for a bit more with WiFi. If you don't mind slightly less IO then you can order an RP-2040 Zero. I got 6 off AliExpress for about $12. Thes…

Unless you're incredibly space constrained I don't really get the point of that 2040 Zero, it just costs more for fewer features. The Pico is already pretty tiny. The Pico is really good at pin interoperability at least, in the land of ESP, what appears to be lots of IO pins quickly turns into barely enough if you're lucky, with pins connected internally to flash or the bootloader or whatever. I really wonder why the…

I think it's about the clones on aliexpress, which are about $2.50, vs $5 for the pico.

Re: I like the RP2040

#140

Post by aaronmdjones »

riskable wrote: post #117
amelius wrote: post #49

Earlier quoted context omitted.

Ok, but does it fulfill military or automotive standards?

I don't know about military standards but there's only ONE automotive standard and it's ISO 26262: https://en.wikipedia.org/wiki/ISO_26262 There's nothing in ISO 26262 that would prevent someone from using an RP2040 in a car. You'd just have to be redundant about everything which you have to do anyway regardless of the chip you choose. Also, ISO 26262 is not a law. It's up to the auto manufacturer whether or not they…

There are several automotive standards for electronic components. GP was probably asking about e.g. AEC-Q100, AEC-Q101, and/or AEC-Q200. These establish that the device is going to work in automotive environments (temperature, humidity, vibration & shock) by verifying functionality while subjecting them to those conditions. A component may work without these tests, but you are merely hoping that that is the case if they haven't been tested. Hope is not a viable strategy for product design.
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