5e271ff31b
`select(rx.receive(), tx.transmit()` had subtle interrupt enable race conditions. Combine receiver and transmitter into one new `PdPhy` struct to disallow the problematic pattern. Scanning through the USB PD 2.0 specification there is no need to have RX and TX running concurrently (after all the USB PD communication is half-duplex).
74 lines
2.4 KiB
Rust
74 lines
2.4 KiB
Rust
#![no_std]
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#![no_main]
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use defmt::{info, Format};
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use embassy_executor::Spawner;
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use embassy_stm32::ucpd::{self, CcPull, CcSel, CcVState, Ucpd};
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use embassy_stm32::Config;
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use embassy_time::{with_timeout, Duration};
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use {defmt_rtt as _, panic_probe as _};
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#[derive(Debug, Format)]
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enum CableOrientation {
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Normal,
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Flipped,
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DebugAccessoryMode,
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}
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// Returns true when the cable
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async fn wait_attached<T: ucpd::Instance>(ucpd: &mut Ucpd<'_, T>) -> CableOrientation {
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loop {
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let (cc1, cc2) = ucpd.cc_vstate();
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if cc1 == CcVState::LOWEST && cc2 == CcVState::LOWEST {
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// Detached, wait until attached by monitoring the CC lines.
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ucpd.wait_for_cc_vstate_change().await;
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continue;
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}
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// Attached, wait for CC lines to be stable for tCCDebounce (100..200ms).
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if with_timeout(Duration::from_millis(100), ucpd.wait_for_cc_vstate_change())
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.await
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.is_ok()
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{
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// State has changed, restart detection procedure.
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continue;
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};
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// State was stable for the complete debounce period, check orientation.
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return match (cc1, cc2) {
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(_, CcVState::LOWEST) => CableOrientation::Normal, // CC1 connected
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(CcVState::LOWEST, _) => CableOrientation::Flipped, // CC2 connected
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_ => CableOrientation::DebugAccessoryMode, // Both connected (special cable)
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};
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}
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}
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#[embassy_executor::main]
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async fn main(_spawner: Spawner) {
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// TODO: Disable DBCC pin functionality by default but have flag in the config to keep it enabled when required.
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let p = embassy_stm32::init(Config::default());
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info!("Hello World!");
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let mut ucpd = Ucpd::new(p.UCPD1, p.PB6, p.PB4, CcPull::Sink);
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info!("Waiting for USB connection...");
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let cable_orientation = wait_attached(&mut ucpd).await;
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info!("USB cable connected, orientation: {}", cable_orientation);
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let cc_sel = match cable_orientation {
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CableOrientation::Normal => {
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info!("Starting PD communication on CC1 pin");
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CcSel::CC1
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}
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CableOrientation::Flipped => {
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info!("Starting PD communication on CC2 pin");
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CcSel::CC2
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}
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CableOrientation::DebugAccessoryMode => panic!("No PD communication in DAM"),
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};
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let mut pd_phy = ucpd.pd_phy(p.DMA1_CH1, p.DMA1_CH2, cc_sel);
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loop {}
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}
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