esptool.py must be on PATH as the script, not a bare esptool binary (else Error::FlashTool).

The four consts are public:

const ESPTOOL: &str

const CHIP: &str

const FLASH_ADDR: &str

const ROM_SETTLE: Duration

use medius::flash;

println!("tool:    {}", flash::ESPTOOL);     // esptool.py
println!("chip:    {}", flash::CHIP);        // esp32s3
println!("address: {}", flash::FLASH_ADDR);  // 0x10000
println!("settle:  {:?}", flash::ROM_SETTLE); // 2s

fn flash(port: &str, bin_path: impl AsRef<Path>, host: bool) -> Result<()>

Blocks

The host flag picks the reboot target: false is RebootTarget::DeviceDownload, true is RebootTarget::HostDownload (see reboot for the full set).

One call reboots the chosen chip into download mode, frees the port, then runs esptool.py write_flash; the firmware-side sequence is on Flashing.

Blocks for the wait plus the tool's runtime, returning Ok(()) on a clean exit else Err(Error::FlashTool).

use medius::flash;

// false -> device chip
flash::flash("/dev/ttyACM0", "device.bin", false)?;

// true -> host chip
flash::flash("/dev/ttyACM0", "host.bin", true)?;

fn esptool_args(port: &str, bin_path: &Path) -> Vec<String>

No round-trip

Builds the exact argv flash passes to esptool.py, without running it. To debug, reboot the chip into download mode via reboot and run these args by hand.

use std::path::Path;
use medius::flash;

let argv = flash::esptool_args("/dev/ttyACM0", Path::new("device.bin"));
println!("esptool.py {}", argv.join(" "));
// esptool.py --chip esp32s3 --port /dev/ttyACM0 --before no_reset
//   --after hard_reset write_flash 0x10000 device.bin

The feature adds Error::FlashTool(String) to the Error enum. It fires when esptool.py can't be spawned (not on PATH) or exits non-zero, the inner String carrying the stderr tail.

use medius::{flash, Error};

match flash::flash("/dev/ttyACM0", "device.bin", false) {
    Ok(()) => println!("flashed"),
    Err(Error::FlashTool(msg)) => {
        eprintln!("flash failed: {msg}");
        eprintln!("hint: is esptool.py on PATH and the port correct?");
    }
    Err(e) => eprintln!("other error: {e}"),
}

flash wraps flash_with; pass a fake CommandRunner and a no-op reboot closure to test without hardware.

fn flash_with<R, F>(port: &str, bin_path: &Path, host: bool, runner: &R, reboot: F) -> Result<()> where R: CommandRunner, F: FnOnce(&str, bool) -> Result<()>

Blocks

// A fake runner records the argv instead of running esptool; the reboot is a no-op.
flash::flash_with("/dev/ttyACM0", bin, false, &recording_runner, |_port, _host| Ok(()))?;