pio/ws2812 example doesn't work in secure boot mode?

[richard9999999999]

PIO/ws2812 example works OK in non secure boot mode however in secure boot mode I see that only first color setting is performed correctly. Did I miss something?

[lurch]

ping @will-v-pi

[will-v-pi]

I can't reproduce this on my board with secure boot, and can't see why it would occur - my guess would be that your wiring is intermittent, which can cause only a single colour to show during the example?

[richard9999999999]

I am using "Waveshare Tiny" module which has Neopixel LED on board:
https://www.waveshare.com/rp2350-tiny.htm
My project is "encryped bootloader example" like, I wanted to use the LED to indicate some bootloader's states however I was not successful. But when I load my binaries to another "Tiny" module, it worked without problem. The only difference was that I have secure boot and glitch detector enabled on module where it doesn't work (and also debug interface disabled). So maybe possible causes(?):
a) the Neopixel LED on one of modules is not fully OK (?)
b) can glitch detector cause some problem?
c) can custom runtime_init_clocks() in encrypted bootloader make some difference? (e.g not fully exact timing so one module is OK, however second is behind tolerances)?

[will-v-pi]

c) can custom runtime_init_clocks() in encrypted bootloader make some difference? (e.g not fully exact timing so one module is OK, however second is behind tolerances)?

Yes, the custom runtime_init_clocks() in encrypted bootloader will run clk_sys from the ROSC, so is very likely to cause problems with ws2812 PIO code as the ROSC has a randomised frequency, and the encrypted bootloader also overstates the ROSC frequency, so anything that relies on precise timing (like the ws2812 PIO code) will not work.

To workaround this, you might be able to switch clk_sys to pll_usb when changing the ws2812 colours then switch back to the ROSC after

[lurch]

@will-v-pi Is it worth adding some example-code to the encrypted bootloader example to show how to switch from ROSC back to XOSC? (Or am I totally misunderstanding all of this? 🤣 )

[will-v-pi]

@will-v-pi Is it worth adding some example-code to the encrypted bootloader example to show how to switch from ROSC back to XOSC? (Or am I totally misunderstanding all of this? 🤣 )

For security you probably shouldn't be doing that as the timing randomisation is part of the security, so probably not - the other peripherals (UART, I2C, etc) are all running from pll_usb so work fine, it's just PIO that has this problem because it's running from clk_sys

[richard9999999999]

OK, all of that makes sense, thank you for explanation. So I'll give up on the idea of ​​using ws2812 in the encrypted bootloader.

[lurch]

(Or am I totally misunderstanding all of this? 🤣 )

Oh! Now I realise where I misunderstood... I thought that you were trying to use the encrypted bootloader to load the pio/ws2812 example, but now I see that you're trying to incorporate ws2812 functionality directly into the encrypted bootloader itself.