refactor: unified host/ communication module, cfg-free run()

- Created host/ module with internal cfg dispatch (USB vs UART)
- Moved usb/task.rs → host/usb.rs, uart/task.rs → host/uart.rs
- Moved protocol_io.rs → host/framing.rs
- Renamed usb_task/uart_task to host_task (uniform name)
- Removed all host-comm cfg from main.rs
- The run() function now has ZERO board-specific conditional compilation
- Deleted old usb/, uart/, protocol_io.rs modules

firmware/src/host/mod.rs

@@ -0,0 +1,16 @@
+//! Host communication: unified USB/UART transport.
+//!
+//! Exports a single `host_task` regardless of transport.
+//! The cfg dispatch is contained entirely within this module.
+
+pub mod framing;
+
+cfg_if::cfg_if! {
+    if #[cfg(feature = "heltec_v3")] {
+        mod uart;
+        pub use uart::host_task;
+    } else {
+        mod usb;
+        pub use usb::host_task;
+    }
+}

firmware/src/host/uart.rs

@@ -1,18 +1,16 @@
-//! UART task: COBS-framed fixed-size LE command/response protocol.
+//! UART host task: COBS-framed fixed-size LE command/response protocol.
 //!
-//! Reads COBS frames from UART, decodes them, parses commands, routes them
+//! Used for boards with USB-UART bridge chips (e.g. CP2102 on Heltec V3).
-//! to the radio or display task, and sends COBS-framed responses back.
-//! Used for boards with USB-UART bridge chips (e.g. CP2102 on some Heltec V3).
 
 use defmt::warn;
 use embassy_executor::task;
 use embedded_io_async::Write;
 
 use crate::channel::{CommandChannel, DisplayCommandChannel, ResponseChannel};
-use crate::protocol_io::{self, CobsDecoder, MAX_FRAME};
+use super::framing::{self, CobsDecoder, MAX_FRAME};
 
 #[task]
-pub async fn uart_task(
+pub async fn host_task(
     parts: crate::board::UartParts,
     commands: &'static CommandChannel,
     responses: &'static ResponseChannel,
@@ -28,8 +26,7 @@ pub async fn uart_task(
     let mut decoder = CobsDecoder::new();
 
     loop {
-        use embassy_futures::select::select;
+        use embassy_futures::select::{select, Either};
-        use embassy_futures::select::Either;
 
         match select(
             embedded_io_async::Read::read(&mut rx, &mut read_buf),
@@ -53,7 +50,7 @@ pub async fn uart_task(
                     let _ = cmds.push(cmd);
                 });
                 for cmd in cmds {
-                    protocol_io::route_command(
+                    framing::route_command(
                         cmd, commands, responses, display_commands, has_display, mac,
                     )
                     .await;
@@ -61,7 +58,7 @@ pub async fn uart_task(
             }
             Either::Second(response) => {
                 if let Some(frame) =
-                    protocol_io::cobs_encode_response(response, &mut write_buf, &mut cobs_encode_buf)
+                    framing::cobs_encode_response(response, &mut write_buf, &mut cobs_encode_buf)
                 {
                     if tx.write_all(frame).await.is_err() {
                         warn!("UART write failed, response dropped");

firmware/src/host/usb.rs

@@ -1,7 +1,4 @@
-//! USB CDC-ACM task: COBS-framed fixed-size LE command/response protocol.
+//! USB CDC-ACM host task: COBS-framed fixed-size LE command/response protocol.
-//!
-//! Reads COBS frames from USB, decodes them, parses commands, routes them
-//! to the radio or display task, and sends COBS-framed responses back.
 
 use defmt::warn;
 use embassy_executor::task;
@@ -11,12 +8,12 @@ use embassy_usb::Builder;
 use static_cell::StaticCell;
 
 use crate::channel::{CommandChannel, DisplayCommand, DisplayCommandChannel, ResponseChannel};
-use crate::protocol_io::{self, CobsDecoder, MAX_FRAME};
+use super::framing::{self, CobsDecoder, MAX_FRAME};
 
 const MAX_PACKET: usize = 64;
 
 #[task]
-pub async fn usb_task(
+pub async fn host_task(
     parts: crate::board::UsbParts,
     commands: &'static CommandChannel,
     responses: &'static ResponseChannel,
@@ -24,10 +21,6 @@ pub async fn usb_task(
     has_display: bool,
     mac: [u8; 6],
 ) {
-    // ── USB device configuration ────────────────────────────────────
-    // VID 0x1209: pid.codes open-source USB vendor ID
-    // PID 0x5741: DongLoRa product ID
-    // Class 0xEF/0x02/0x01: Miscellaneous / Interface Association Descriptor
     let mut config = embassy_usb::Config::new(0x1209, 0x5741);
     config.manufacturer = Some("DongLoRa");
     config.product = Some("DongLoRa LoRa Radio");
@@ -36,7 +29,6 @@ pub async fn usb_task(
     config.device_protocol = 0x01;
     config.composite_with_iads = true;
 
-    // Use MAC address as USB serial number for unique device identification.
     static SERIAL_BUF: StaticCell<[u8; 12]> = StaticCell::new();
     let serial_buf = SERIAL_BUF.init([0u8; 12]);
     const HEX: &[u8; 16] = b"0123456789ABCDEF";
@@ -64,18 +56,9 @@ pub async fn usb_task(
     let mut usb_dev = builder.build();
     let (sender, receiver) = class.split();
 
-    // ── Run USB device + protocol loop concurrently ────────────────
     join(
         usb_dev.run(),
-        protocol_loop(
+        protocol_loop(sender, receiver, commands, responses, display_commands, has_display, mac),
-            sender,
-            receiver,
-            commands,
-            responses,
-            display_commands,
-            has_display,
-            mac,
-        ),
     )
     .await;
 }
@@ -89,8 +72,7 @@ async fn protocol_loop<'d, D: embassy_usb_driver::Driver<'d>>(
     has_display: bool,
     mac: [u8; 6],
 ) {
-    use embassy_futures::select::select3;
+    use embassy_futures::select::{select3, Either3};
-    use embassy_futures::select::Either3;
 
     let mut read_buf = [0u8; MAX_PACKET];
     let mut write_buf = [0u8; MAX_FRAME];
@@ -102,7 +84,7 @@ async fn protocol_loop<'d, D: embassy_usb_driver::Driver<'d>>(
         match select3(
             receiver.read_packet(&mut read_buf),
             responses.receive(),
-            embassy_time::Timer::after_millis(250), // DTR poll interval for disconnect detection
+            embassy_time::Timer::after_millis(250),
         )
         .await
         {
@@ -122,7 +104,7 @@ async fn protocol_loop<'d, D: embassy_usb_driver::Driver<'d>>(
                     let _ = cmds.push(cmd);
                 });
                 for cmd in cmds {
-                    protocol_io::route_command(
+                    framing::route_command(
                         cmd, commands, responses, display_commands, has_display, mac,
                     )
                     .await;
@@ -130,7 +112,7 @@ async fn protocol_loop<'d, D: embassy_usb_driver::Driver<'d>>(
             }
             Either3::Second(response) => {
                 if let Some(frame) =
-                    protocol_io::cobs_encode_response(response, &mut write_buf, &mut cobs_encode_buf)
+                    framing::cobs_encode_response(response, &mut write_buf, &mut cobs_encode_buf)
                 {
                     for chunk in frame.chunks(MAX_PACKET) {
                         if sender.write_packet(chunk).await.is_err() {
@@ -140,12 +122,9 @@ async fn protocol_loop<'d, D: embassy_usb_driver::Driver<'d>>(
                     }
                 }
             }
-            Either3::Third(()) => {
+            Either3::Third(()) => {}
-                // Poll DTR every 250ms to detect host disconnect
-            }
         }
 
-        // Check DTR after every select wake
         let connected = receiver.dtr();
         if was_connected && !connected && has_display {
             display_commands.send(DisplayCommand::Reset).await;

firmware/src/main.rs

@@ -25,15 +25,11 @@ mod display;
 mod driver;
 #[cfg(not(test))]
 mod hal;
+#[cfg(not(test))]
+mod host;
 mod protocol;
 #[cfg(not(test))]
 mod radio;
-#[cfg(not(test))]
-mod protocol_io;
-#[cfg(all(not(test), feature = "heltec_v3"))]
-mod uart;
-#[cfg(all(not(test), not(feature = "heltec_v3")))]
-mod usb;
 
 #[cfg(not(test))]
 use embassy_executor::Spawner;
@@ -90,10 +86,8 @@ async fn run(spawner: Spawner) {
         .spawn(radio::radio_task(radio, &COMMANDS, &RESPONSES, &STATUS))
         .expect("spawn radio_task");
 
-    cfg_if::cfg_if! {
-        if #[cfg(feature = "heltec_v3")] {
     spawner
-                .spawn(uart::uart_task(
+        .spawn(host::host_task(
             comm,
             &COMMANDS,
             &RESPONSES,
@@ -101,20 +95,7 @@ async fn run(spawner: Spawner) {
             has_display,
             mac,
         ))
-                .expect("spawn uart_task");
+        .expect("spawn host_task");
-        } else {
-            spawner
-                .spawn(usb::usb_task(
-                    comm,
-                    &COMMANDS,
-                    &RESPONSES,
-                    &DISPLAY_COMMANDS,
-                    has_display,
-                    mac,
-                ))
-                .expect("spawn usb_task");
-        }
-    }
 
     if let Some(dp) = display {
         spawner

firmware/src/uart/mod.rs

@@ -1,4 +0,0 @@
-//! UART interface with COBS-framed command/response protocol.
-
-mod task;
-pub use task::uart_task;

firmware/src/usb/mod.rs

@@ -1,4 +0,0 @@
-//! USB CDC-ACM interface with COBS-framed command/response protocol.
-
-mod task;
-pub use task::usb_task;