XPost: sci.electronics.design   
   From: jl@650pot.com   
      
   On Tue, 17 Sep 2024 17:21:36 +0100, The Natural Philosopher   
    wrote:   
      
   >On 17/09/2024 17:09, john larkin wrote:   
   >> On Tue, 17 Sep 2024 11:07:17 +0100, The Natural Philosopher   
   >>  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.   
   >>>>   
   >>>> 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.   
   >>>   
   >>> 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.   
   >>   
   >> You had me worried!   
   >>   
   >   
   >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.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)