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I like the RP2040

dgroshev.com

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Re: I like the RP2040

#381

Post by 15155 »

sshine wrote: post #14
orlp wrote: post #8

Earlier quoted context omitted.

The bootloader is read-only. What the bootloader loads isn't. If the thing you're trying to boot into is faulty, it doesn't matter because you can just replace the thing the bootloader is trying to load. If the bootloader itself was faulty, the device would be bricked.

To elaborate on the alternative: When the bootloader is not read-only, you can upload another bootloader. This is great in a different way because custom bootloaders allow for more flexibility. For example, you may want to keep two copies of your firmware on the chip: One that you're uploading, and one you can fall back to if the most recent one has problems. This protects you against failure during firmware upload o…

Or you can just write/add a second-stage bootloader after the ROM bootloader and get the best of both worlds?

By the way - real commercial MCUs have boot ROMs with connected watchdogs, trial boots, and recovery boot processes.

Re: I like the RP2040

#382

Post by 15155 »

dragontamer wrote: post #137
floxy wrote: post #107

Earlier quoted context omitted.

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. ----- 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 so…

JLC's polished stencils will happily work at 0.2mm pitch for ~$10.

Re: I like the RP2040

#383

Post by 15155 »

Havoc wrote: post #123
eulgro wrote: post #24

Earlier quoted context omitted.

It's not a BGA, it's a QFN with a ground pad.

I see. What does that change in terms of process needed?

BGAs generally call for more complicated reflow profiles (including vapor phase reflow for very large BGAs - think 40mm+ FPGAs) and require X-ray inspection (if doing inspection at all.) BGA balls can have under-body solder voids, etc. BGA devices also generally specify a specific solder to use (leaded or lead-free won't be interchangeable.)

Generally, all single-row package pin layouts are easier than double-row (BGA, WLCSP, 2-row QFN) to reflow.

Re: I like the RP2040

#384

Post by 15155 »

jcalvinowens wrote: post #288
riskable wrote: post #131

Earlier quoted context omitted.

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 c…

I'm speaking from experience, I built two boards with the rp2040 before I decided to stop using it. The pin flexibility is nice, I agree with you there. But I spend more time dealing with the flash chip than that saves me. I don't want more capability. An STM32 M3 has far far more processing throughput than I need for 99.9% of what I do. I want the smaller thing, even if it isn't cheaper. It is sufficient. I love stm…

How much time does it take to place a DFN-8 flash chip and 6 routes in reality?

The RP2040 is absolutely usable from simple registers and documentation, not sure where you got this idea.

The reason you want multiple megabytes of space in a professional product: identically-sized bootloader partitions for trial boots.

Re: I like the RP2040

#385

Post by 15155 »

jcalvinowens wrote: post #298
jcalvinowens wrote: post #288

Earlier quoted context omitted.

I'm speaking from experience, I built two boards with the rp2040 before I decided to stop using it. The pin flexibility is nice, I agree with you there. But I spend more time dealing with the flash chip than that saves me. I don't want more capability. An STM32 M3 has far far more processing throughput than I need for 99.9% of what I do. I want the smaller thing, even if it isn't cheaper. It is sufficient. I love stm…

I forgot another win for the STM32: no crystal.

Why are the STM32 ring oscillators any different than the one in the RP2040? (If you mean crystal-free USB FS - yeah, that's a nice little feature, but this is the only difference that I am aware of.)

Re: I like the RP2040

#386

Post by 15155 »

bangaladore wrote: post #66
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.

That chip has over 10x less RAM and only 60k flash. It has only one core and that core is clocked at half the speeds compared to both the RP2040 cores. And it cost six bucks from US distributors. I can buy a single RP2040 chip from Digikey for 70 cents. Even if you add another dollar for flash memory, you are still far better off.

Try the PY32 series MCUs for better bang-for-your-buck: https://www.lcsc.com/products/Microcontroller-Units-MCUs-MPU...

Re: I like the RP2040

#387

Post by 15155 »

the__alchemist wrote: post #57
joezydeco wrote: post #52

Earlier quoted context omitted.

Are you gated on PCB real estate, or cost? 8 megabits of QSPI is under 50 cents. I really don't care that it's external if the entire chipset is under 2 bucks.

Not the OP, but I'll say, whenever designing a fresh board, this sort of convenience built-in is nice. Individually, it's not a huge deal, but when you start adding things that are sometimes built in (external crystal vice internal? flash? PDs on USB or a bus?), you appreciate when it's one less component to allow spacing for, that might be out of stock at a given order etc. Also note that QSPI flash has a number of…

QSPI NOR flash pins are labeled basically the same on every single MCU, routed using the same guidelines, etc.

DFN-8 ICs take up 2x3mm and take 30 seconds to route.

Re: I like the RP2040

#388

Post by 15155 »

Brusco_RF wrote: post #364
airbreather wrote: post #359

I currently design a product that needs to be battery powered and its just not possible in the same way on the 2040 as esp32 with the ULP and the deep sleep current.

I also happen to be working on an ultra-low power project with an ESP32. It is hard to beat that 5uA deep-sleep current!

Try active current consumption on the Ambiq Apollo4 chips.

Re: I like the RP2040

#389

Post by 15155 »

snvzz wrote: post #307

Dreaming about a smaller, lower-power yet faster RISC-V CPU (many cores exist that are strong against cortex-M0+) with the RP2040's peripherals.

Zero of these MCUs have anything resembling the quality of CoreSight/CMSIS-DAP/Keil/etc.

Re: I like the RP2040

#390

Post by 15155 »

demondemidi wrote: post #332

Does the RPI boot rom have DFU built in? If not, it can be bricked.

Not "DFU" as in an implementation of the USB DFU 1.1 class, but a hardware boot ROM with spiritually the same mechanisms exists.
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