switch to bbqueue, simplified feedback

Cargo.lock

@@ -2,6 +2,15 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "aho-corasick"
+version = "1.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ddd31a130427c27518df266943a5308ed92d4b226cc639f5a8f1002816174301"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "atomic-polyfill"
 version = "1.0.3"
@@ -26,6 +35,17 @@ dependencies = [
  "rustc_version 0.2.3",
 ]
 
+[[package]]
+name = "bbqueue"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68917624e17aad88607cb5a5936f6da9b607c48c711e4e9ed101e7189aed28c2"
+dependencies = [
+ "const-init",
+ "critical-section",
+ "maitake-sync",
+]
+
 [[package]]
 name = "bitfield"
 version = "0.13.2"
@@ -63,6 +83,22 @@ dependencies = [
  "embedded-io",
 ]
 
+[[package]]
+name = "cc"
+version = "1.2.61"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d16d90359e986641506914ba71350897565610e87ce0ad9e6f28569db3dd5c6d"
+dependencies = [
+ "find-msvc-tools",
+ "shlex",
+]
+
+[[package]]
+name = "cfg-if"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
+
 [[package]]
 name = "cipher"
 version = "0.4.4"
@@ -73,6 +109,22 @@ dependencies = [
  "inout",
 ]
 
+[[package]]
+name = "const-init"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4bd422bfb4f24a97243f60b6a4443e63d810c925d8da4bb2d8fde26a7c1d57ec"
+
+[[package]]
+name = "cordyceps"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "688d7fbb8092b8de775ef2536f36c8c31f2bc4006ece2e8d8ad2d17d00ce0a2a"
+dependencies = [
+ "loom",
+ "tracing",
+]
+
 [[package]]
 name = "cortex-m"
 version = "0.7.7"
@@ -214,6 +266,27 @@ dependencies = [
  "num",
 ]
 
+[[package]]
+name = "find-msvc-tools"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5baebc0774151f905a1a2cc41989300b1e6fbb29aff0ceffa1064fdd3088d582"
+
+[[package]]
+name = "generator"
+version = "0.8.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "52f04ae4152da20c76fe800fa48659201d5cf627c5149ca0b707b69d7eef6cf9"
+dependencies = [
+ "cc",
+ "cfg-if",
+ "libc",
+ "log",
+ "rustversion",
+ "windows-link",
+ "windows-result",
+]
+
 [[package]]
 name = "generic-array"
 version = "0.14.7"
@@ -238,13 +311,13 @@ dependencies = [
 name = "guac"
 version = "0.1.0"
 dependencies = [
+ "bbqueue",
  "cortex-m",
  "cortex-m-rt",
  "defmt 1.0.1",
  "defmt-rtt",
  "embedded-hal 1.0.0",
  "embedded-io",
- "heapless 0.9.3",
  "log-to-defmt",
  "lpc55-hal",
  "nb 1.1.0",
@@ -296,16 +369,6 @@ dependencies = [
  "stable_deref_trait",
 ]
 
-[[package]]
-name = "heapless"
-version = "0.9.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "25ba4bd83f9415b58b4ed8dc5714c76e626a105be4646c02630ad730ad3b5aa4"
-dependencies = [
- "hash32 0.3.1",
- "stable_deref_trait",
-]
-
 [[package]]
 name = "inout"
 version = "0.1.4"
@@ -315,6 +378,18 @@ dependencies = [
  "generic-array 0.14.7",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
+[[package]]
+name = "libc"
+version = "0.2.186"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68ab91017fe16c622486840e4c83c9a37afeff978bd239b5293d61ece587de66"
+
 [[package]]
 name = "lock_api"
 version = "0.4.14"
@@ -341,6 +416,19 @@ dependencies = [
  "log",
 ]
 
+[[package]]
+name = "loom"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "419e0dc8046cb947daa77eb95ae174acfbddb7673b4151f56d1eed8e93fbfaca"
+dependencies = [
+ "cfg-if",
+ "generator",
+ "scoped-tls",
+ "tracing",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "lpc55-hal"
 version = "0.5.0"
@@ -371,6 +459,37 @@ dependencies = [
  "vcell",
 ]
 
+[[package]]
+name = "maitake-sync"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3d77c365d697828821727b9bc09e6bc3c518b8c63804e79e1be5a5ae091a7c5f"
+dependencies = [
+ "cordyceps",
+ "critical-section",
+ "loom",
+ "mutex-traits",
+ "mycelium-bitfield",
+ "pin-project",
+ "portable-atomic",
+ "tracing",
+]
+
+[[package]]
+name = "matchers"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d1525a2a28c7f4fa0fc98bb91ae755d1e2d1505079e05539e35bc876b5d65ae9"
+dependencies = [
+ "regex-automata",
+]
+
+[[package]]
+name = "memchr"
+version = "2.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8ca58f447f06ed17d5fc4043ce1b10dd205e060fb3ce5b979b8ed8e59ff3f79"
+
 [[package]]
 name = "modular-bitfield"
 version = "0.13.1"
@@ -392,6 +511,18 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "mutex-traits"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3929f2b5633d29cf7b6624992e5f3c1e9334f1193423e12d17be4faf678cde3f"
+
+[[package]]
+name = "mycelium-bitfield"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24e0cc5e2c585acbd15c5ce911dff71e1f4d5313f43345873311c4f5efd741cc"
+
 [[package]]
 name = "nb"
 version = "0.1.3"
@@ -407,6 +538,15 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8d5439c4ad607c3c23abf66de8c8bf57ba8adcd1f129e699851a6e43935d339d"
 
+[[package]]
+name = "nu-ansi-term"
+version = "0.50.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
+dependencies = [
+ "windows-sys",
+]
+
 [[package]]
 name = "num"
 version = "0.3.1"
@@ -469,6 +609,12 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "once_cell"
+version = "1.21.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
+
 [[package]]
 name = "panic-halt"
 version = "1.0.0"
@@ -485,6 +631,32 @@ dependencies = [
  "defmt 1.0.1",
 ]
 
+[[package]]
+name = "pin-project"
+version = "1.1.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cbf0d9e68100b3a7989b4901972f265cd542e560a3a8a724e1e20322f4d06ce9"
+dependencies = [
+ "pin-project-internal",
+]
+
+[[package]]
+name = "pin-project-internal"
+version = "1.1.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a990e22f43e84855daf260dded30524ef4a9021cc7541c26540500a50b624389"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "pin-project-lite"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
+
 [[package]]
 name = "portable-atomic"
 version = "1.13.1"
@@ -537,6 +709,23 @@ version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
 
+[[package]]
+name = "regex-automata"
+version = "0.4.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e1dd4122fc1595e8162618945476892eefca7b88c52820e74af6262213cae8f"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc897dd8d9e8bd1ed8cdad82b5966c3e0ecae09fb1907d58efaa013543185d0a"
+
 [[package]]
 name = "rustc_version"
 version = "0.2.3"
@@ -561,6 +750,12 @@ version = "1.0.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b39cdef0fa800fc44525c84ccb54a029961a8215f9619753635a9c0d2538d46d"
 
+[[package]]
+name = "scoped-tls"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e1cf6437eb19a8f4a6cc0f7dca544973b0b78843adbfeb3683d1a94a0024a294"
+
 [[package]]
 name = "scopeguard"
 version = "1.2.0"
@@ -588,6 +783,27 @@ version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 
+[[package]]
+name = "sharded-slab"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f40ca3c46823713e0d4209592e8d6e826aa57e928f09752619fc696c499637f6"
+dependencies = [
+ "lazy_static",
+]
+
+[[package]]
+name = "shlex"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
+
+[[package]]
+name = "smallvec"
+version = "1.15.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "67b1b7a3b5fe4f1376887184045fcf45c69e92af734b7aaddc05fb777b6fbd03"
+
 [[package]]
 name = "spin"
 version = "0.9.8"
@@ -649,6 +865,76 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "thread_local"
+version = "1.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f60246a4944f24f6e018aa17cdeffb7818b76356965d03b07d6a9886e8962185"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "tracing"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "63e71662fa4b2a2c3a26f570f037eb95bb1f85397f3cd8076caed2f026a6d100"
+dependencies = [
+ "pin-project-lite",
+ "tracing-attributes",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-attributes"
+version = "0.1.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7490cfa5ec963746568740651ac6781f701c9c5ea257c58e057f3ba8cf69e8da"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "tracing-core"
+version = "0.1.36"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db97caf9d906fbde555dd62fa95ddba9eecfd14cb388e4f491a66d74cd5fb79a"
+dependencies = [
+ "once_cell",
+ "valuable",
+]
+
+[[package]]
+name = "tracing-log"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee855f1f400bd0e5c02d150ae5de3840039a3f54b025156404e34c23c03f47c3"
+dependencies = [
+ "log",
+ "once_cell",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-subscriber"
+version = "0.3.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cb7f578e5945fb242538965c2d0b04418d38ec25c79d160cd279bf0731c8d319"
+dependencies = [
+ "matchers",
+ "nu-ansi-term",
+ "once_cell",
+ "regex-automata",
+ "sharded-slab",
+ "smallvec",
+ "thread_local",
+ "tracing",
+ "tracing-core",
+ "tracing-log",
+]
+
 [[package]]
 name = "typenum"
 version = "1.20.0"
@@ -684,6 +970,12 @@ dependencies = [
  "usb-device",
 ]
 
+[[package]]
+name = "valuable"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba73ea9cf16a25df0c8caa16c51acb937d5712a8429db78a3ee29d5dcacd3a65"
+
 [[package]]
 name = "vcell"
 version = "0.1.3"
@@ -710,3 +1002,27 @@ checksum = "de437e2a6208b014ab52972a27e59b33fa2920d3e00fe05026167a1c509d19cc"
 dependencies = [
  "vcell",
 ]
+
+[[package]]
+name = "windows-link"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
+
+[[package]]
+name = "windows-result"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7781fa89eaf60850ac3d2da7af8e5242a5ea78d1a11c49bf2910bb5a73853eb5"
+dependencies = [
+ "windows-link",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.61.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae137229bcbd6cdf0f7b80a31df61766145077ddf49416a728b02cb3921ff3fc"
+dependencies = [
+ "windows-link",
+]

Cargo.toml

@@ -4,17 +4,18 @@ version = "0.1.0"
 edition = "2024"
 
 [features]
-default = ["ak4490"]
+default = ["ak4490", "dma"]
 ak4490 = []
+dma = []
 
 [dependencies]
+bbqueue = "0.7.0"
 cortex-m = { version = "0.7.7", features = ["critical-section-single-core"] }
 cortex-m-rt = "0.7.5"
 defmt = "1.0.1"
 defmt-rtt = "1.1.0"
 embedded-hal = "1.0.0"
 embedded-io = "0.7.1"
-heapless = "0.9.3"
 log-to-defmt = "0.1.0"
 lpc55-hal = { version = "0.5.0", path = "../usbd_uac2/examples/lpc55-hal" }
 nb = "1.1.0"

src/main.rs

@@ -7,8 +7,10 @@ fn panic() -> ! {
     panic_probe::hard_fault()
 }
 
-use core::ptr::null_mut;
+use bbqueue::nicknames::Churrasco;
-use core::sync::atomic::{AtomicBool, AtomicI32, AtomicUsize, Ordering};
+use bbqueue::prod_cons::stream::{StreamConsumer, StreamProducer};
+use bbqueue::traits::bbqhdl::BbqHandle;
+use core::sync::atomic::{AtomicBool, AtomicI32, AtomicU32, AtomicUsize, Ordering};
 use cortex_m_rt::entry;
 use defmt;
 use defmt::debug;
@@ -20,10 +22,8 @@ use hal::prelude::*;
 use hal::raw as pac;
 use hal::time::Hertz;
 use hal::typestates::pin::state::Gpio;
-use heapless::spsc::Consumer;
+use lpc55_hal as hal;
-use lpc55_hal::{self as hal};
 use pac::interrupt;
-use static_cell::StaticCell;
 use usb_device::{
     bus::{self},
     device::{StringDescriptors, UsbDeviceBuilder, UsbVidPid},
@@ -44,9 +44,10 @@ mod hw;
 
 // Fo = M/(N*2*P) * Fin
 // Fo = 3072/(125*2*8) * 16MHz = 24.576MHz
-const FIFO_LENGTH: usize = 128; // frames
+//
+const FIFO_LENGTH: usize = 256; // frames
 const MCLK_FREQ: u32 = 24576000;
-const SAMPLE_RATE: u32 = 48000;
+const SAMPLE_RATE: u32 = 88200;
 type SampleType = (i32, i32);
 
 struct CodecPins {
@@ -68,8 +69,8 @@ impl Clock {
 impl UsbAudioClockImpl for Clock {
     const CLOCK_TYPE: usbd_uac2::descriptors::ClockType = ClockType::InternalFixed;
     const SOF_SYNC: bool = false;
-    fn get_sample_rate(&self) -> core::result::Result<u32, usbd_uac2::UsbAudioClassError> {
+    fn get_sample_rate(&self) -> u32 {
-        Ok(self.cur_rate)
+        self.cur_rate
     }
     fn set_sample_rate(
         &mut self,
@@ -81,7 +82,7 @@ impl UsbAudioClockImpl for Clock {
             // hal::wait_at_least(1);
             self.pins.sel_24m.set_high().ok();
         } else {
-            defmt::info!("[clock] 24M clock selected");
+            defmt::info!("[clock] 22M clock selected");
             self.pins.sel_24m.set_low().ok();
             // hal::wait_at_least(1);
             self.pins.sel_22m.set_high().ok();
@@ -154,19 +155,57 @@ impl defmt::Format for PerfCounters {
     }
 }
 
-static FIFO_CONSUMER_STORE: StaticCell<Consumer<SampleType>> = StaticCell::new();
+const BYTES_PER_FRAME: usize = 8;
-static mut FIFO_CONSUMER: *mut Consumer<SampleType> = null_mut();
+const QUEUE_BYTES: usize = FIFO_LENGTH * BYTES_PER_FRAME;
+// We use bbqueue here for performance in the USB driver that runs almost entirely in interrupt free critical section.
+static QUEUE: Churrasco<QUEUE_BYTES> = Churrasco::new();
+// Used for feedback calculation of current fifo state
+static PRODUCED: AtomicU32 = AtomicU32::new(0);
+static CONSUMED: AtomicU32 = AtomicU32::new(0);
 
 static PERF: PerfCounters = PerfCounters {
     received_frames: AtomicUsize::new(0),
     played_frames: AtomicUsize::new(0),
-    min_fill: AtomicUsize::new(FIFO_LENGTH),
+    min_fill: AtomicUsize::new(FIFO_LENGTH), // not recording this for now, need to figure out how to make it meaningful, since the queue starts empty
     avg_fill: AtomicUsize::new(FIFO_LENGTH / 2),
-    queue_underflows: AtomicUsize::new(0),
+    queue_underflows: AtomicUsize::new(0), // ditto here, since we underflow at startup, but we record this one as it can be trended
     queue_overflows: AtomicUsize::new(0),
     audio_underflows: AtomicUsize::new(0),
 };
 
+fn cur_fill() -> u32 {
+    PRODUCED
+        .load(Ordering::Acquire)
+        .wrapping_sub(CONSUMED.load(Ordering::Acquire))
+        / BYTES_PER_FRAME as u32
+}
+
+#[inline]
+fn try_write_one_frame<T: BbqHandle>(
+    cons: &mut StreamConsumer<T>,
+    i2s: &pac::i2s7::RegisterBlock,
+) -> bool {
+    if let Ok(rgr) = cons.read() {
+        if rgr.len() >= BYTES_PER_FRAME {
+            let l = u32::from_le_bytes(rgr[0..4].try_into().unwrap());
+            let r = u32::from_le_bytes(rgr[4..8].try_into().unwrap());
+
+            i2s.fifowr.write(|w| unsafe { w.bits(l) });
+            i2s.fifowr.write(|w| unsafe { w.bits(r) });
+
+            // consume exactly one frame (8 bytes)
+            rgr.release(BYTES_PER_FRAME);
+            PERF.played_frames.fetch_add(1, Ordering::Relaxed);
+            CONSUMED.fetch_add(BYTES_PER_FRAME as u32, Ordering::Relaxed);
+            return true;
+        } else {
+            // Not enough bytes for a full frame: leave it in the queue.
+            return false;
+        }
+    }
+    false
+}
+
 #[interrupt]
 fn FLEXCOMM7() {
     let i2s = unsafe { &*pac::I2S7::ptr() };
@@ -176,28 +215,26 @@ fn FLEXCOMM7() {
     }
 
     // refil the buffer to 4 frames / 8 samples
-    let fifo = unsafe { &mut *FIFO_CONSUMER };
+    let mut cons = QUEUE.stream_consumer();
     while i2s.fifostat.read().txlvl().bits() <= 6 {
-        if let Some((l, r)) = fifo.dequeue() {
+        if !try_write_one_frame(&mut cons, i2s) {
-            i2s.fifowr.write(|w| unsafe { w.bits(l as u32) });
+            // No complete frame available: write silence to keep FIFO above threshold
-            i2s.fifowr.write(|w| unsafe { w.bits(r as u32) });
-            PERF.min_fill.fetch_min(fifo.len(), Ordering::Relaxed);
-            PERF.played_frames.fetch_add(1, Ordering::Relaxed);
-        } else {
             PERF.queue_underflows.fetch_add(1, Ordering::Relaxed);
             i2s.fifowr.write(|w| unsafe { w.bits(0) });
             i2s.fifowr.write(|w| unsafe { w.bits(0) });
+            break;
         }
     }
 }
 
-struct Audio<'a> {
+struct Audio<T: BbqHandle> {
     running: AtomicBool,
     i2s: I2sTx,
-    producer: heapless::spsc::Producer<'a, SampleType>,
+    producer: StreamProducer<T>,
     integrator: AtomicI32,
+    filtered_fill: AtomicI32,
 }
-impl<'a> Audio<'a> {
+impl<T: BbqHandle> Audio<T> {
     fn start(&self) {
         self.running.store(true, Ordering::Relaxed);
         defmt::info!("playback starting, enabling interrupts");
@@ -218,8 +255,8 @@ impl<'a> Audio<'a> {
         pac::NVIC::mask(pac::Interrupt::FLEXCOMM7);
     }
 }
-impl<'a, B: bus::UsbBus> UsbAudioClass<'a, B> for Audio<'_> {
+impl<T: BbqHandle, B: bus::UsbBus> UsbAudioClass<'_, B> for Audio<T> {
-    fn alternate_setting_changed(&mut self, terminal: usb_device::UsbDirection, alt_setting: u8) {
+    fn alternate_setting_changed(&mut self, _terminal: usb_device::UsbDirection, alt_setting: u8) {
         match alt_setting {
             0 => self.stop(),
             1 => self.start(),
@@ -228,7 +265,7 @@ impl<'a, B: bus::UsbBus> UsbAudioClass<'a, B> for Audio<'_> {
     }
     fn audio_data_rx(
         &mut self,
-        ep: &usb_device::endpoint::Endpoint<'a, B, usb_device::endpoint::Out>,
+        ep: &usb_device::endpoint::Endpoint<'_, B, usb_device::endpoint::Out>,
     ) {
         let mut buf = [0; SAMPLE_RATE as usize / 1000 * 64];
         let len = match ep.read(&mut buf) {
@@ -239,64 +276,58 @@ impl<'a, B: bus::UsbBus> UsbAudioClass<'a, B> for Audio<'_> {
             }
         };
         let buf = &buf[..len];
-        for sample in buf.chunks_exact(8).map(|b| {
+        if let Ok(mut wg) = self.producer.grant_exact(buf.len()) {
-            PERF.received_frames.fetch_add(1, Ordering::Relaxed);
+            wg.copy_from_slice(buf);
-            (
+            wg.commit(buf.len());
-                i32::from_le_bytes(b[..4].try_into().unwrap()),
+            PRODUCED.fetch_add(buf.len() as u32, Ordering::Relaxed);
-                i32::from_le_bytes(b[4..].try_into().unwrap()),
+            PERF.received_frames
-            )
+                .fetch_add(buf.len() / BYTES_PER_FRAME, Ordering::Relaxed);
-        }) {
+        } else {
-            if let Err(e) = self.producer.enqueue(sample) {
+            PERF.queue_overflows.fetch_add(1, Ordering::Relaxed);
-                PERF.queue_overflows.fetch_add(1, Ordering::Relaxed);
+            defmt::error!("overflowed bbq, asked {}", buf.len());
-                // defmt::error!("overflowed fifo, len: {}", unsafe {
-                //     (*self.producer.get()).len()
-                // });
-            }
         }
     }
-    fn feedback(&mut self) -> Option<UsbIsochronousFeedback> {
+    fn feedback(&mut self, nominal_rate: UsbIsochronousFeedback) -> Option<UsbIsochronousFeedback> {
-        const TARGET: i32 = FIFO_LENGTH as i32 / 2 - 64;
+        let target = FIFO_LENGTH as i32 / 2 - nominal_rate.int as i32;
-        const NOMINAL: i32 = (SAMPLE_RATE as i32 / 1000) << 16;
 
-        let queuelen = self.producer.len();
+        let fill = cur_fill() as i32;
-        let error = (queuelen as i32 - TARGET).clamp(-32, 32);
+        let prev = self.filtered_fill.load(Ordering::Relaxed);
+        let filtered = prev + ((fill - prev) >> 4); // ~1/16 smoothing
+        self.filtered_fill.store(filtered, Ordering::Relaxed);
 
-        // --- integrator ---
+        let error = filtered - target;
-        let scaled_error = error / 64;
 
-        let new_i = self.integrator.fetch_add(scaled_error, Ordering::Relaxed) + scaled_error;
+        // Clamp startup excursions.
-        let clamped = new_i.clamp(-131072, 131072);
+        let error = error.clamp(-(nominal_rate.int as i32 * 4), nominal_rate.int as i32 * 4);
 
-        // leak + store final value
+        // Reset integrator when the error is small
-        let leaked = clamped - (clamped >> 8);
+        if error.abs() < 2 {
-        self.integrator.store(leaked, Ordering::Relaxed);
-
-        // reset on large deviation
-        if error.abs() > 96 {
             self.integrator.store(0, Ordering::Relaxed);
         }
+        let mut integrator = self.integrator.load(Ordering::Relaxed);
+        integrator = integrator - (integrator >> 6); // ~1/64 leak, reduce windup
 
-        // --- gains ---
+        integrator = integrator.clamp(-256, 256);
-        let p = error / 128;
+        self.integrator.store(integrator, Ordering::Relaxed);
-        let i = leaked / 32768;
 
-        // correction
+        // gains
-        let correction = (-(p + i)).clamp(-32, 32);
+        let p = error << 3;
-        let v = NOMINAL + (correction << 10);
+        let i = integrator * 0; // disabled for now
 
-        // EMA (unchanged, already correct)
+        let correction = -((p + i) >> 2);
-        let ema = PERF.avg_fill.load(Ordering::Relaxed);
+        let nominal_v = nominal_rate.to_u32_12_13() as i32;
-        let new = ((ema * 1023) + queuelen + 512) >> 10;
+
-        PERF.avg_fill.store(new, Ordering::Relaxed);
+        let mut v = nominal_v + correction;
+
+        // Tight clamp around nominal.
+        v = v.clamp(nominal_v - (1 << 12), nominal_v + (1 << 12));
 
         defmt::debug!(
-            "q:{} p:{} i:{} err:{} fb:{}+{}",
+            "fill:{} err:{} int:{} fb:{=u32:x}",
-            queuelen,
+            fill,
-            p,
-            i,
             error,
-            NOMINAL >> 16,
+            integrator,
-            correction
+            v
         );
 
         Some(UsbIsochronousFeedback::new(v as u32))
@@ -393,7 +424,6 @@ fn main() -> ! {
     let mut anactrl = hal.anactrl;
     let mut pmc = hal.pmc;
     let mut syscon = hal.syscon;
-
     let mut gpio = hal.gpio.enabled(&mut syscon);
     let mut iocon = hal.iocon.enabled(&mut syscon);
 
@@ -459,6 +489,7 @@ fn main() -> ! {
         .flexcomm
         .4
         .enabled_as_i2c(&mut syscon, &clocks.support_flexcomm_token().unwrap());
+
     let mut i2c_bus = I2cMaster::new(
         i2c_peripheral,
         codec_i2c_pins,
@@ -486,21 +517,13 @@ fn main() -> ! {
 
     defmt::debug!("codec init");
     dac::init_dac(&mut i2c_bus, codec_gpio_pins);
-    let queue = cortex_m::singleton!(
-        : heapless::spsc::Queue<SampleType, FIFO_LENGTH>
-        = heapless::spsc::Queue::new()
-    )
-    .unwrap();
-    let (producer, consumer) = queue.split();
-
-    let consumer_ref = FIFO_CONSUMER_STORE.init(consumer);
-    unsafe { FIFO_CONSUMER = consumer_ref as *mut _ };
 
     let mut audio = Audio {
         i2s: i2s_peripheral,
-        producer,
+        producer: QUEUE.stream_producer(),
         running: AtomicBool::new(false),
         integrator: AtomicI32::new(0),
+        filtered_fill: AtomicI32::new(0),
     };
 
     let config = AudioClassConfig::new(UsbSpeed::High, FunctionCode::Other, &mut clock, &mut audio)
@@ -512,7 +535,7 @@ fn main() -> ! {
                 bit_resolution: 32,
                 bytes_per_sample: 4,
             },
-            TerminalType::ExtLineConnector,
+            TerminalType::OutHeadphones,
             ChannelConfig::default_chans(2),
             IsochronousSynchronizationType::Asynchronous,
             LockDelay::Undefined(0),