Re: RP2040 reset idea

On Tue, 17 Sep 2024 17:21:36 +0100, The Natural Philosopher
<tnp@invalid.invalid> wrote:
 

On 17/09/2024 17:09, john larkin wrote:

On Tue, 17 Sep 2024 11:07:17 +0100, The Natural Philosopher
<tnp@invalid.invalid> wrote:
>

On 17/09/2024 03:58, john larkin wrote:

The RP2040 has a cool mode where it can be made to boot up with the
USB port looking like a memory stick. That's great for software
installs or upgrades. The Pico board has a BOOT button on the board;
if the pico is powered up with the button pushed, it goes into that
boot mode.
>
But if I have a product (actually a family of products) in a nice
aluminum box, a user would have to remove the top cover, remove all
power sources (there can be three), and hold the button down while
reconnecting power.
>
Some of my customers also want to lock a box such that it's impossible
to write to any nonvolatile memory while it's in a secure area.
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So here's an idea: a small hole in the box allows a toothpick or a
paper clip to push a button. A short push is a regular reset. A long
push is a memory-stick mode boot. We can have a rotary switch LOCK
hole too.
>

Thats' what my PICO powered thermostats have. For the onboard button though
Resetting is done by pulling the power.
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The point is that if you do power up with the button pressed, you wipe
the entire FLASH RAM I think.
>

>
My Pi guy verifies that entering boot mode doesn't change the contents
of flash. Power cycle and things run like before.
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You had me worried!
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>
Really?
>
I guess whenever I entered that mode it was to download fresh code...

 It looks like a USB memory stick. You can delete or add files if you
want.
 It boots CPU 0 (the one we call Alice) from a file with the extension
.UL2
 Why   .UL2   one wonders.
 We'll put a bunch of files into the flash. Code for Bob, the 2nd CPU.
An FPGA bitstream file. A prototype calibration table. A README file
to explain everything in plain English.