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I like the RP2040

dgroshev.com

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Re: I like the RP2040

#391

Post by 15155 »

dragontamer wrote: post #166
IshKebab wrote: post #36

TL;DR: he likes it because there's only one version available, whereas most microcontrollers have many more than one variant. This seems like a very weak argument. IMO (just based on the specs; haven't actually used it), the main reason to use this is for the PIO stuff. That's a very niche use case though.

> IMO (just based on the specs; haven't actually used it), the main reason to use this is for the PIO stuff. That's a very niche use case though. PIO is interesting but I'm not fully convinced they're better than a suite of dedicated timers, especially in the realm of power-efficiency. The _real_ wtf?!?!? spec here is 264kB of SRAM. At this price point / power-consumption, that's a _LOT_ of SRAM. Any application that…

PIO-like speeds (50MHz+ - easy) are unobtainable across parallel GPIOs in any MCU without a similar core (NXP FlexIO, TI PRU) or an FPGA.

PIO has its use cases.

Re: I like the RP2040

#392

Post by 15155 »

metadat wrote: post #67

If this RPi main chip costs $0.70, why does the finished product currently cost $93.00 (RPi 5)? They're quite expensive nowadays, I miss when you could purchase them for ~$30.00. Meanwhile, Expressif chips are literally everywhere and becoming ever more ubiquitous. Edit: Thanks friends for the correction. It is cool you can still buy an RPi Pico for $13.00 :)

If you're paying $13 for a Pico, you're getting fleeced.

These are $4 or less at most vendors, and JLC will assemble 5 for you for <$3/ea.

Re: I like the RP2040

#393

Post by 15155 »

fxtentacle wrote: post #155

The real competition is the STM32 line-up, in my opinion. Much more computing power at a comparable price. Or half price if you only need a few MHz.

The real competition are Chinese WCH MCUs and STM32 clones (PY32 series.)

Add $1.00 and you're into Cortex M7s with vastly more peripherals/power (NXP IMXRT1011.)

Re: I like the RP2040

#394

Post by 15155 »

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…

The vast majority of real, commercial MCUs do not have WiFi in-package. The ESP32 is unique in this regard and is one of its only redeeming features.

I would rather buy the RP2040 and the NRF7001/NRF7002 for the same or less total cost and have a substantially better wireless solution (5.4GHz WiFi 6).

Re: I like the RP2040

#395

Post by 15155 »

crote wrote: post #167
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.

The most annoying part about the PIO is that there are only two of them (though with 4 sub-units each), they only have space for 32 instructions, and they don't have an external clock input. They are great for implementing very basic peripherals, but more than once I've started to implement something more complex just to realize it would be unacceptably slow and run out of space. If they were to beef them up just a l…

Add a $2.80 ICE40 with built-in NVM and your problems are solved.

Re: I like the RP2040

#396

Post by snvzz »

15155 wrote: post #389
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.

Of course not, those are proprietary technologies specific to ARM.

If anything, they implement RISC-V debug and trace specs, or earlier vendor-specific, as these specs are relatively new.

Re: I like the RP2040

#397

Post by 15155 »

snvzz wrote: post #396
15155 wrote: post #389

Earlier quoted context omitted.

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

Of course not, those are proprietary technologies specific to ARM. If anything, they implement RISC-V debug and trace specs, or earlier vendor-specific, as these specs are relatively new.

Which is why I stated "resembling." TIL about the RV debug/trace specs, this has been one of my major complaints. The vendor-specific stuff is plainly terrible.

I don't see anything like SWD being consistently defined by this spec, though?

Re: I like the RP2040

#398

Post by crote »

stefan_ wrote: post #175
crote wrote: post #153

I have mixed feelings about the RP2040. On the one hand, it's a great chip for hobbyists. It's cheap, it's easily available, it's easy to build a board around, and it offers plenty of stuff for your average application. On the other hand, it's definitely a bit lacking from a professional perspective. The peripherals are fine , but once you start looking into the details it's easy to run into limitations. That XIP int…

What do you mean by USB-C PHY? USB-C is the connector, and you can run USB 1.1/2.0/3.0/3.1 through it, but realistically a RP2040 can not feed even a USB 2.0 PHY.

A PHY for the USB PD communication over the CC wires. That makes it possible to negotiate things like Alt Modes for a USB-C connector. DIYing one is surprisingly hard due to the voltages and timing involved.

Re: I like the RP2040

#399

Post by crote »

kragen wrote: post #215
crote wrote: post #153

I have mixed feelings about the RP2040. On the one hand, it's a great chip for hobbyists. It's cheap, it's easily available, it's easy to build a board around, and it offers plenty of stuff for your average application. On the other hand, it's definitely a bit lacking from a professional perspective. The peripherals are fine , but once you start looking into the details it's easy to run into limitations. That XIP int…

i'm curious what kinds of applications you've found fram most useful for. it seems like a really cool technology, but the price point is so high that i struggle to understand when you'd use it rather than a combination of sram (or psram) and nand

The main application here would be that the RP2040 only has a single XIP QSPI bus. If you extend its memory by hooking up PSRAM to that bus, you can't boot because the chip loads all its code from QSPI. If you hook flash up to that bus, you don't have any way to add extra memory.

FRAM would allow you to have your cake and write it: your application code survives a reboot, and (if the chip were to gain write support) the remaining space could be treated like PSRAM.

Re: I like the RP2040

#400

Post by crote »

dfox wrote: post #174
crote wrote: post #153

I have mixed feelings about the RP2040. On the one hand, it's a great chip for hobbyists. It's cheap, it's easily available, it's easy to build a board around, and it offers plenty of stuff for your average application. On the other hand, it's definitely a bit lacking from a professional perspective. The peripherals are fine , but once you start looking into the details it's easy to run into limitations. That XIP int…

I suspect that the Synopsys DesignWare SSI macro in RP2040 can in fact be used for R/W PSRAM or FRAM, but the abridged documentation of it in RP2040 datasheet is not sufficient for one to configure it that way.

Ooh, good point! I should definitely look into that.
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