[UCPD] Configuration Channel (CC) handling

examples/stm32g4/src/bin/usb_c_pd.rs

@@ -0,0 +1,62 @@
+#![no_std]
+#![no_main]
+
+use defmt::{info, Format};
+use embassy_executor::Spawner;
+use embassy_stm32::{
+    ucpd::{self, CcPull, CcVState, Ucpd},
+    Config,
+};
+use embassy_time::{with_timeout, Duration};
+use {defmt_rtt as _, panic_probe as _};
+
+#[derive(Debug, Format)]
+enum CableOrientation {
+    Normal,
+    Flipped,
+    DebugAccessoryMode,
+}
+
+// Returns true when the cable
+async fn wait_attached<'d, T: ucpd::Instance>(ucpd: &mut Ucpd<'d, T>) -> CableOrientation {
+    loop {
+        let (cc1, cc2) = ucpd.cc_vstate();
+        if cc1 == CcVState::LOWEST && cc2 == CcVState::LOWEST {
+            // Detached, wait until attached by monitoring the CC lines.
+            ucpd.wait_for_cc_change().await;
+            continue;
+        }
+
+        // Attached, wait for CC lines to be stable for tCCDebounce (100..200ms).
+        if with_timeout(Duration::from_millis(100), ucpd.wait_for_cc_change())
+            .await
+            .is_ok()
+        {
+            // State has changed, restart detection procedure.
+            continue;
+        };
+
+        // State was stable for the complete debounce period, check orientation.
+        return match (cc1, cc2) {
+            (_, CcVState::LOWEST) => CableOrientation::Normal,  // CC1 connected
+            (CcVState::LOWEST, _) => CableOrientation::Flipped, // CC2 connected
+            _ => CableOrientation::DebugAccessoryMode,          // Both connected (special cable)
+        };
+    }
+}
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    // TODO: Disable DBCC pin functionality by default but have flag in the config to keep it enabled when required.
+    let p = embassy_stm32::init(Config::default());
+
+    info!("Hello World!");
+
+    let mut ucpd = Ucpd::new(p.UCPD1, p.PB6, p.PB4, CcPull::Sink);
+
+    info!("Waiting for USB connection...");
+    let cable_orientation = wait_attached(&mut ucpd).await;
+    info!("USB cable connected, orientation: {}", cable_orientation);
+
+    loop {}
+}