
Sipeed Longan Nano – RISC-V Development Board - childintime
https://www.seeedstudio.com/Sipeed-Longan-Nano-RISC-V-GD32VF103CBT6-Development-Board-p-4205.html
======
omgtehlion
Datasheets are here:
[http://dl.sipeed.com/LONGAN/Nano/DOC/](http://dl.sipeed.com/LONGAN/Nano/DOC/)

As from my experience with GD's STM32 clones, they did not have a real flash,
but copied all your code from SPI-like internal flash to main SRAM on startup.
I wonder if they did pull the same stunt with GD32V's

EDIT: what is inside stm32 clone:
[https://zeptobars.com/en/read/GD32F103CBT6-mcm-serial-
flash-...](https://zeptobars.com/en/read/GD32F103CBT6-mcm-serial-flash-Giga-
Devices)

EDIT2: original page now returns 404, it was this board:
[http://dl.sipeed.com/LONGAN/Nano/Spec/Sipeed%20longan%20nano...](http://dl.sipeed.com/LONGAN/Nano/Spec/Sipeed%20longan%20nano%20Datasheet%20V1.0.pdf)
for $4.90
([https://www.seeedstudio.com/catalogsearch/result/?cat=&q=GD3...](https://www.seeedstudio.com/catalogsearch/result/?cat=&q=GD32VF103CBT6))

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kevin_thibedeau
Executing from flash is patent encumbered.

~~~
monocasa
Do what now? People have been executing out of flash for longer than patents
are valid.

~~~
kevin_thibedeau
STM32 has special its ART accelerator cache to prefetch instruction lines from
flash and significantly reduce wait states. A clone can't replicate the same
performance with a bog standard flash peripheral.

[https://www.embedded.com/electronics-blogs/break-
points/4440...](https://www.embedded.com/electronics-blogs/break-
points/4440388/On-wait-states)

~~~
monocasa
I know about ART. I actually have some contributions to the STM32F4 reference
manual as my team had access to pre production silicon. There's bugs in the
prefetching on that thing on early revs and you need to flip a chicken bit.

I still don't see anything in there that's not the usual way flash is accessed
in cases where it's mapped into the address space for XIP applications. Hell,
a lot of the time people will stick something nicer than a dog simple direct
mapped cache like ST's implementation.

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non-entity
Pardon my ignorance, but besides being an open-source ISA what's the reason
for the popularity for RISC-V? The buzz alone has piqued my interest, but I'm
just trying to understand the "why".

~~~
pjc50
As someone who works in a famous mixed-signal IC company, I note that almost
everything I've heard about it comes from HN and not internal discussion.
Instruction sets are just not where the leading edge of value creation is. And
the design and manufacture costs of ICs remain pretty irreducible. People
expecting lots of open source hardware to suddenly start popping up are going
to be disappointed.

An instruction set is an API. It's the architecture behind it that matters.

~~~
GoblinSlayer
Targeting all use cases with x86 is not unusual?

~~~
pjc50
I'm not sure what the argument is here?

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antoniuschan99
I been using esp8266 but have been looking to learn more about STM32 and
RIsc-v since its closer to the hardware.

On a commercial standpoint, wroom-02 is fcc pre certified. An example of the
sipeed nano dev board with WiFi on board is this, which uses esp8265

[https://www.seeedstudio.com/Sipeed-MAIX-I-module-WiFi-
versio...](https://www.seeedstudio.com/Sipeed-MAIX-I-module-WiFi-version-1st-
RISC-V-64-AI-Module-K210-inside-p-3206.html)

If someone were to use STM32 for business logic, why wouldnt they just use an
esp8266 since its a microcontroller, wifi, and the wroom-02 is pre certified?

Also, for clarification. The STM32 is based off of ARM Architechture. Whereas
the Sipeed Longan Nano competes against the STM32 but is RISC-V based?

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fuzzybear3965
How I can distinguish news discussing a processor core design (seemingly,
usually, marketed as a "core") from that discussing hardware that I can
actually buy (a processor "chip")?

I would have thought that 1\. [https://blog.westerndigital.com/risc-v-swerv-
core-open-sourc...](https://blog.westerndigital.com/risc-v-swerv-core-open-
source/) 2\. [https://greenwaves-
technologies.com/ai_processor_gap8/](https://greenwaves-
technologies.com/ai_processor_gap8/) and 3\.
[https://syntacore.com/page/products/processor-
ip/scr1](https://syntacore.com/page/products/processor-ip/scr1)

would be pieces of hardware that I can buy. Instead, they seem to be designs
for hardware which conform to the RISC-V ISA, which could then be fabbed by a
semiconductor manufacturer or flashed onto an FPGA.

What marketing/technical terms distinguish the designs of these systems from
their implementations? "Core", "processor", "MCU"/"microcontroller", for
example? Are any/all of these uniquely constrained to describing either a
design (on paper) or that design's physical implementation in hardware?

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marshray
As a tinkerer:

1\. I can read the official specs without agreeing to an onerous license.

2\. There are several open source implementations I can choose to run on an
FPGA.

3\. I can choose the simplest combination of features. Want a multiply
instruction, but no branch prediction? Want caching but no MMU requiring
multi-level address virtualization?

A large processor vendor has to employ a small army of processor designers.
The trend will always be in the direction of adding more features and
increasing complexity. Customers will write code to require those features,
and the cycle continues.

Only very rarely a fresh design will appear having the right combination of
attributes to give it a chance of being a viable platform for a long time.
This is what makes Risk-V attractive to me.

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ncmncm
A longan is an asian fruit related to the lychee.

FYI ICYWW NTIM

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whydoyouasking
Beware! Opinionated comment!

Seeedstudio is such ignorant to their customers. Delivery of my order failed
due to local mail and person from other side of customer "support" email
rejected even to write a request to mail service. I'm not talking about
compensation and/or resend.

~~~
whydoyouasking
I wonder who's that [-] was.

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greybox
404 page not found - maybe the product was de-listed?

~~~
Randor
Well,

I'm getting a 404 too so I am guessing that the page was removed.

~~~
codetrotter
Page works fine for me. Maybe it was a temporary problem?

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omegabravo
it's still 404 for me, so I opened it in private mode and it appeared.

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ivl
This was an instant click but it seems the site is being hugged down.

