I got almost all of my wishes granted with RP2350 • Hacker News Board

Re: I got almost all of my wishes granted with RP2350

#351

Post by jercos » Sun, Aug 11, 2024, 8:21 PM UTC

jacobmarble wrote: post #345

andylinpersonal wrote: post #312

Earlier quoted context omitted.

Indeed an in-package winbond flash die though.

Please explain. What is a better alternative that could have been chosen? I’m just happy to have one fewer component on my boards.

Downside is it occupies a CS on the QSPI controller, presumably bonding to the same pads as the QSPI pins on the package, so now you only have one external memory IC. It's a very small tradeoff all things considered, but is still technically a tiny disadvantage over highly integrated MCUs.

A potential alternative would have been a directly memory-mapped NOR flash die, but that would have required more bond wires, more dedicated pads on the die, a port on the bus, and on top of that the memory die would have been more expensive too.

An older (and often impractical) alternative is to use a single die with both flash and SoC on, in the same process. This usually forces a larger-than-desired process node to match the flash technology, making the SoC take up more space. The result requires no extra bond wires or pads, but now you're really manufacturing a flash chip with an MCU attached.

Re: I got almost all of my wishes granted with RP2350

#352

Post by jercos » Sun, Aug 11, 2024, 8:39 PM UTC

guenthert wrote: post #290

swetland wrote: post #45

Lots of nice improvements here. The RISC-V RV32I option is nice -- so many RV32 MCUs have absurdly tiny amounts of SRAM and very limited peripherals. The Cortex M33s are a biiig upgrade from the M0+s in the RP2040. Real atomic operations. An FPU. I'm exited.

Many people seem excited about the FPU. Could you help me understand what hardware floating point support is needed in a MCU for? I remember DSPs using (awkward word-size) fixed point arithmetic.

I think you highlight the exact issue rather well... fixed-point DSP instructions are awkward to use. The FPU and the double-precision hardware with its baked operations work with IEEE floats out of the box, so the programmer can be "lazy." A thousand new programmers can write something like `* 0.7` in C++ inside a tight loop without it stealing 200 instructions from the timing of the rest of the program.

Re: I got almost all of my wishes granted with RP2350

#353

Post by zedcombination » Mon, Aug 12, 2024, 3:51 PM UTC

jsheard wrote: post #3

Speak of the devil: https://news.ycombinator.com/item?id=41156743 Very nice that the "3" turned out to mean the modern M33 core rather than the much older M3 core. It has a real FPU!

Yes, it's pretty lame that Raspberry Pi has such a "flexible" definition of "low power". i.e. the RP2350 is not low power at all.

Looks like Espressif will keep getting my business. What a missed opportunity by RPI.

Re: I got almost all of my wishes granted with RP2350

#354

Post by rscott2049 » Tue, Aug 13, 2024, 2:37 PM UTC

rscott2049 wrote: post #348

TaylorAlexander wrote: post #342

Earlier quoted context omitted.

Do you have your code publicly available? I was just discussing with a friend it would be nice to add an optional Ethernet mode to my motor controller, but the limitations of this library or other approaches limit the appeal. Also, are there any other approaches that might be better and would offer 100meg or even gigabit links with the RP2350? Thanks!

I'm still working on it - hopefully will be on the DECstation2040 github soon. The interface uses the LAN8720/8740 MAC chips, which provide 10/100 Mbit. (I haven't tried 10 Mbit, so no idea if it works or not). FYI, here's a test result: ping -q -i 0.005 192.168.1.6 PING 192.168.1.6 (192.168.1.6) 56(84) bytes of data. 229501/229501 packets, 0% loss, min/avg/ewma/max = 0.063/76.725/88.698/160.145 ms 295393/295987 pack…

If anybody is still following this thread, I fixed the problem: sudo ping -f 192.168.1.6 -s 1473 PING 192.168.1.6 (192.168.1.6) 1473(1501) bytes of data. 347751/347752 packets, 0% loss, min/avg/ewma/max = 0.573/0.625/0.628/1.002 ms 375962/375963 packets, 0% loss, min/avg/ewma/max = 0.573/0.625/0.626/1.002 ms 45876717/45876724 packets, 0% loss, min/avg/ewma/max = 0.570/0.626/0.630/3.972 ms ..^C --- 192.168.1.6 ping statistics --- 48237616 packets transmitted, 48237608 received, 1.65846e-05% packet loss, time 31011738ms rtt min/avg/max/mdev = 0.570/0.626/3.972/0.011 ms, ipg/ewma 0.642/0.627 ms

Turns out I wasn't passing the RX data properly to LWIP...

Re: I got almost all of my wishes granted with RP2350

#355

Post by vardump » Wed, Aug 14, 2024, 10:10 PM UTC

rscott2049 wrote: post #354

rscott2049 wrote: post #348

Earlier quoted context omitted.

I'm still working on it - hopefully will be on the DECstation2040 github soon. The interface uses the LAN8720/8740 MAC chips, which provide 10/100 Mbit. (I haven't tried 10 Mbit, so no idea if it works or not). FYI, here's a test result: ping -q -i 0.005 192.168.1.6 PING 192.168.1.6 (192.168.1.6) 56(84) bytes of data. 229501/229501 packets, 0% loss, min/avg/ewma/max = 0.063/76.725/88.698/160.145 ms 295393/295987 pack…

If anybody is still following this thread, I fixed the problem: sudo ping -f 192.168.1.6 -s 1473 PING 192.168.1.6 (192.168.1.6) 1473(1501) bytes of data. 347751/347752 packets, 0% loss, min/avg/ewma/max = 0.573/0.625/0.628/1.002 ms 375962/375963 packets, 0% loss, min/avg/ewma/max = 0.573/0.625/0.626/1.002 ms 45876717/45876724 packets, 0% loss, min/avg/ewma/max = 0.570/0.626/0.630/3.972 ms ..^C --- 192.168.1.6 ping st…

So roughly 19 Mbps, up and down? Although I guess ping is not an optimal bandwidth test.

Re: I got almost all of my wishes granted with RP2350

#356

Post by cstrahan » Tue, Aug 20, 2024, 8:54 PM UTC

bee_rider wrote: post #249

speed_spread wrote: post #228

Earlier quoted context omitted.

> English, so weird Borrowed from just-as-weird French "piquer" - to stab or jab.

It is kind of funny that both of the incorrect versions, peaked or peeked, sort of make more sense just based on the definitions of the individual words. “Peaked my interest” in particular could be interpreted as “reached the top of my interest.” Way better than stabbing my interest, in a French fashion or otherwise.

I think it makes more sense if you consider the expression "this tickles my fancy".

Why do we use "tickle" there? Because a tickle is a type of stimulation, and "fancy" here means "interest", so one is effectively saying "this stimulates my interest".

If we then consult Oxford Language's definition of pique, we find:

> stimulate (interest or curiosity). "you have piqued my curiosity about the man"

The word "piqued" in "this piqued my curiosity" serves as something along the lines of: stimulated, aroused, provoked

This is aligned with the French word "piquer", as a "prick" or "sting" (much like a tickle) would stimulate/arouse/provoke.