Notices by pedro 🍉 (ubik@fedi.turbofish.cc)

I wrote some ST7789 screen driver Rust code which just takes bytes from memory and flushes them into the screen. It seems to work but somehow the screen turns completely white less than one second after the memory write operation. This used to work fine, so I was wondering if maybe some other driver was interfering with the SPI, but nope, I disabled everything else and it still does that. I wrote a small test program which uses a different library to speak to the ST, and it works just fine. I am probably doing something wrong somewhere, BUT THEN WHY WAS IT WORKING OK BEFORE? I suspect some weird timing issues. Or maybe my driver code is being optimized by the compiler somehow, and things are not being done in the correct order?

I will probably plug in a logic analyzer tomorrow, but if anyone has any tips on how to debug it...

#st7789 #embeddedrust #embedded #rust #electronics

@bino yeah, i have one of those logic analyzers, thanks! and no keep-alive is necessary AFAIK. thanks!

@bino so, I hooked up the logic analyzer and suddenly the whole thing started working. I narrowed it down to the screen's RST pin. If I leave it connected to the analyzer, it works. If I disconnect it, the whole thing turns white. I thought maybe some pull-up/pull-down effect might be going on, but this is just an output pin...

@bino OH, I FOUND THE PROBLEM. I think this had already bit me in the ass once. Basically, in the framework I'm using (Embassy), whenever a pin structure is dropped (not sure if you're familiar with Rust, but that's when it goes out of scope), it resets the pin's config. I stored the pin in a parent struct, to make sure it stays in scope, and it now just works. So much time wasted trying to figure this one out... Anyway, thanks for your help!

Really, yodeling and alphorns? Are you kidding me? #esc2025

@evan I missed the original post with the poll. I blame the Mastodon interface.

@evan the Alhambra? The Eiffel Tower? Pompeii?

@evan also Kek Lok Si and Batu Caves. La Sagrada Familia. the Empire State Building.

@br00t4c WTF, Romania?

I can't believe it's 2025 and the media are discussing ethnic cleansing as if it were something on which people should be able to hold opinions.

@dragoniff2 @ct_bergstrom maybe it's just a bird's vacation photos.

@lxo @pluralistic em Portugal, bostificação não vai colar. Pun intended.

Stolen from Bluesky

@jwildeboer Nope. https://www.theguardian.com/world/live/2025/jan/15/israel-gaza-war-live-ceasefire-hostage-deal-benjamin-netanyahu-hamas?page=with:block-6787f0828f08ce4b9f2daef7#block-6787f0828f08ce4b9f2daef7

Repórter: "O crescimento do CHEGA assusta-o?"
Manuel Alegre: "ó homem, eu fui preso pela PIDE." #legislativas2024