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A WeatherFlow Tempest UDP Broadcast Receiver in Golang, Rust, Swift, and C++

by hrbrmstr on January 28, 2022

After a Twitter convo about weather stations I picked up a WeatherFlow Tempest. Setup was quick, but the sensor package died within 24 hours. I was going to give up on it but I had written an R package (for the REST API & UDP broadcast interfaces) and C++ utility (for just the UDP broadcast interface), and the support staff were both friendly and competent and sent me a replacement super quick.

I’ve blathered about the R package already (on Twitter) so am not going to tag that here, but will link to a few repositories (in various languages) that receive the UDP broadcast messages and at least shove them to stdout.

The C++ one is mostly C but gets the job done (it just posts the messages to stdout). It should run everywhere but I only tested on macOS & Linux, because Windows is a terrible operating system nobody should use.

The Golang one has some structured types to consume about half of the JSON messages (I’ve only seen four in the broadcasts so far, and will add more as I see new ones). It’s only more verbose than the C++ one due to the various record type handling. This should run everywhere, though.

For kicks, I threw together a Swift one that is really just Swift-ified C and is a Frankenstein monster that likely shouldn’t be used. (I’ll be making a SwiftUI macOS/iOS/iPadOS app for the UDP broadcast messages, though, soon).

To round out my obsession I also made a Rust version which I’m just in 💙 with (not because of any skill of my own). It’s the smallest source file and is pretty elegant (100% due to Rust, and, again, not me).

All the code/projects are super small, but the Rust source is so tiny that it won’t be too intrusive to post here:

use std::net::UdpSocket;

fn main() -> std::io::Result<()> {

  let mut buf = [0; 1024]; // 1024 byte buffer is plenty
  let s = UdpSocket::bind("0.0.0.0:50222").expect(r#"{"message":"Could not bind to address/port."}"#);

  loop {

    let (n, _) = s.recv_from(&mut buf).expect(r#"{"message":"No broadcasts received."}"#);

    println!("{}", String::from_utf8(buf[..n].to_vec()).unwrap())

  }

}

FIN

If you’re interested in a low-cost weather station with great DIY programming support, I’d definitely (so far, at least) recommend the Tempest. We’ll see if it survives the forthcoming snowpocalypse.

These are the JSON messages it slings over UDP:

{"serial_number":"HB-00069665","type":"hub_status","firmware_revision":"177","uptime":728643,"rssi":-50,"timestamp":1643246011,"reset_flags":"BOR,PIN,POR","seq":72787,"radio_stats":[25,1,0,3,16637],"mqtt_stats":[10,108]}
{"serial_number":"ST-00055227","type":"rapid_wind","hub_sn":"HB-00069665","ob":[1643246013,0.00,0]}
{"serial_number":"ST-00055227","type":"rapid_wind","hub_sn":"HB-00069665","ob":[1643246015,0.00,0]}
{"serial_number":"ST-00055227","type":"device_status","hub_sn":"HB-00069665","timestamp":1643246016,"uptime":106625,"voltage":2.683,"firmware_revision":165,"rssi":-72,"hub_rssi":-66,"sensor_status":655364,"debug":0}
{"serial_number":"ST-00055227","type":"obs_st","hub_sn":"HB-00069665","obs":[[1643246016,0.00,0.00,0.00,0,3,1024.56,-12.82,47.84,0,0.00,0,0.000000,0,0,0,2.683,1]],"firmware_revision":165}

*** This is a Security Bloggers Network syndicated blog from rud.is authored by hrbrmstr. Read the original post at: https://rud.is/b/2022/01/28/a-weatherflow-tempest-udp-broadcast-receiver-in-golang-rust-swift-and-c/

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