09:58 <Ralph[m]> there seems to be no discussion open yet for next weeks wg meeting - since [the last](https://github.com/rust-embedded/wg/discussions/846) didn't really happen: would it make sense to just rename that?

09:58 <Ralph[m]> (i won't be around next tuesday, but i think the points i raised can easily be discussed without my presence)

12:47 <Farooq> I've got a W2812B to program which seems to use 1 wire protocol. Is this something my MCU needs to support at hardware level, or something which I should implement in the software?

12:57 <Ralph[m]> <Farooq> "I've got a W2812B to program..." <- i presume you mean ws2812b? i've never used it but it seems common (it gets referenced in the chat regularly) and there are various crates around: https://crates.io/search?q=ws2812

12:57 <Ralph[m]> this then e.g. leads to this one: https://crates.io/crates/ws2812-spi

12:57 <Ralph[m]> and more generic (which uses the former): https://crates.io/crates/smart-leds

13:11 <Farooq> mine doesn't use spi. it uses 1 wire

13:13 <Farooq> s/W2812B/Ws2812B/

13:13 <Farooq> it's ws2812b not ws2812

13:15 <jannic[m]> It's the same. And no, it's not SPI, the ws2812-spi crate only misuses the peripheral. Alternatively, you can bit bang the protocol.

14:01 <Farooq> eh?

14:01 <Farooq> that's not misuse. that's abuse

14:01 <Farooq> report poor spi abuse to the authorities

14:03 <RobWells[m]> Well there’s also an implementation for ESP chips that uses the RMT (remote control) peripheral, so pick your poison.

14:11 <JamesMunns[m]> You can (ab)use the pwm or i2s peripherals on the nrf52 to drive them too :)

14:24 <Farooq> what about usb? XD

14:24 <Farooq> or ethernet

14:38 <JamesMunns[m]> Nope, not that I'm aware of. I2S can have arbitrary datastreams and 2.4MHz is a multiple of the 800khz carrier frequency you need, and the PWM engine on the nrf52 is very custom, at the cost that it takes 16x more bytes to encode pwm sequences than it does the raw data

14:39 <JamesMunns[m]> s/custom/customizable/

14:40 <JamesMunns[m]> The issue with using SPI on the nrf52 is that it only supports power of two frequencies, which don't have good multiples with the 800khz carrier frequency you need for ws2812b stuff

14:40 <JamesMunns[m]> whereas the stm32 you can pick a much more specific frequency

14:44 <sirhcel[m]> Has anyone a recommendation for tooling for checking stack frame sizes for an embedded rust application (cortex-m, mixed with c, but even jutst rust will help a lot)?

14:46 <sirhcel[m]> I tried `-Z emit-stack-sizes` and `cargo-call-stack` so far without success. I'm cross-compiling and have the appropriate target (thumbv8m.main-none-eabihf) installed. But just setting `RUSTFLAGS` to `-Z... (full message at <https://catircservices.org/_irc/v1/media/download/ASndVPo9AwkBvPK4T63_Ydumf-RktiiuaOMJlG5rYQ0CAFEaXYc_F6RhhRBkJgGBxTu6AtoGImy9U6n6svAzPXy_8AAAAAAAAGNhdGlyY3NlcnZpY2VzLm9yZy9oaXBhTFVlb25JSnNka2R4UXBiUExlcUI>)

14:47 <JamesMunns[m]> try rustup +nightly target add thumbv8m.main-none-eabihf

14:48 <JamesMunns[m]> (or rustup target add thumbv8m.main-none-eabihf --toolchain=nightly)

14:48 <JamesMunns[m]> you probably have it installed on your stable toolchain but not your nightly toolchain

14:49 <sirhcel[m]> JamesMunns[m]: Awesome! Thank you very much! That's one step forward. :)

14:58 <sirhcel[m]> And the first build is over the finish line. ❤️

15:03 <Ralph[m]> <JamesMunns[m]> "try rustup +nightly target..." <- i really like having a `rust-toolchain.toml` in my repos where i just define the `toolchain.targets` so that cargo picks it up automatically. since i started doing that i didn't have to manually install targets anymore (either locally or in CI) 🙂

15:27 <sirhcel[m]> `cargo-call-stack` does not produce a binary with the current nightly toolchain. Building following the [unstable rust book](https://doc.rust-lang.org/beta/unstable-book/compiler-flags/emit-stack-sizes.html... (full message at <https://catircservices.org/_irc/v1/media/download/ARpyGqemDjwB3ri8O-J9v_Svaj12deOAiP1H0AvsuaA-Spv6rlDpz7YOqS0hT9O1cONRcb7WUBLhiZSMA46goIS_8AAAAAAAAGNhdGlyY3NlcnZpY2VzLm9yZy9kVmhScWFPT1BndUNIUU9OU3F1VVhDUmM>)

15:29 <sirhcel[m]> Had anyone success with generating stack frame size information in the recent past?

16:17 <dngrs[m]> Someone here was looking for bit flags crates a while ago iirc? Here's an idiomatic enum based one https://github.com/enarx/flagset

16:17 <dngrs[m]> (spotted by [Daniel aka CyReVolt 🐢](https://matrix.to/#/@CyReVolt:matrix.org))

16:18 <DanielakaCyReVol> happy to share that finding :)

23:53 <JamesMunns[m]> By the way, started writing some high level docs of what I'm working on with `ergot`, as a possible future entry into the `postcard` cinematic universe: https://docs.rs/ergot/latest/ergot/book/index.html

23:56 <JamesMunns[m]> Ask me anything (please do: it will help me write good docs), feel free to check it out if it sounds interesting (there are demos you can run to connect multiple nodes!), if you feel like hacking on it with me, feel free to drop by https://matrix.to/#/#mnemos-dev:beeper.com, or just open an issue or something :)