[Gnuk-users] Gnuk on a faster MCU

NIIBE Yutaka gniibe at fsij.org
Thu Sep 14 05:42:14 UTC 2017

Aurelien Jarno <aurelien at aurel32.net> wrote:
> Also those MCU seems to only have 256B of cache, and for what I have
> seen on the STM32L, the cache is important to mask the wait states and
> get good performances.

Thank you.  I see.

Let me write about another topic.

We have "SYS" routines for STM32F103 in Chopstx.  I named it as system
service routines, as I wrote some in chopstx/mcu/ABOUT-SYS.  It is used
for STM32F103 boards, mainly, because STM32F103 cannot change the first
4KB flash ROM by its running program and it doesn't have USB support
from its boot ROM.

Gnuk (and NeuG) supports the feature of upgrading program through USB,
using these SYS routines.

I think that the restriction of STM32F103 is strange and peculiar, from
the viewpoint of newer implementations of MCU with USB.  I guess that
USB was not that mature or it required more code size.

Nowadays, most MCU would support flash ROM programming through USB by
boot ROM.  For those MCUs, all that Gnuk would need is to erase all
flash ROM;  Next reset let MCU go into "boot mode", and a user can use
standard tool to program its MCU.

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