diff --git a/Cargo.toml b/Cargo.toml
index e3138ee1..6712d3b0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -44,9 +44,16 @@ step-decoder = []
 record-ui-test = ["serde", "serde_json"]
 test-ui-replay = ["serde", "serde_json"]
 debug-region-map = []
+test-cynthion = []
 
 [[test]]
 name = "test_replay"
 path = "src/test_replay.rs"
 harness = false
 required-features = ["test-ui-replay"]
+
+[[test]]
+name = "test_cynthion"
+path = "src/test_cynthion.rs"
+harness = false
+required-features = ["test-cynthion"]
diff --git a/src/capture.rs b/src/capture.rs
index ff2af8c7..efaddfa5 100644
--- a/src/capture.rs
+++ b/src/capture.rs
@@ -1005,7 +1005,7 @@ impl CaptureReader {
 }
 
 impl EndpointReader {
-    fn transfer_data_range(&mut self, range: &Range<EndpointTransactionId>)
+    pub fn transfer_data_range(&mut self, range: &Range<EndpointTransactionId>)
         -> Result<Range<EndpointDataEvent>, Error>
     {
         let first_data_id = self.data_transactions.bisect_left(&range.start)?;
@@ -1013,7 +1013,7 @@ impl EndpointReader {
         Ok(first_data_id..last_data_id)
     }
 
-    fn transfer_data_length(&mut self, range: &Range<EndpointDataEvent>)
+    pub fn transfer_data_length(&mut self, range: &Range<EndpointDataEvent>)
         -> Result<u64, Error>
     {
         if range.start == range.end {
diff --git a/src/lib.rs b/src/lib.rs
index 72ffaec1..957e9b12 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,8 +1,8 @@
 #[macro_use]
 extern crate bitfield;
 
-mod backend;
-mod capture;
+pub mod backend;
+pub mod capture;
 mod compact_index;
 mod data_stream;
 pub mod decoder;
diff --git a/src/test_cynthion.rs b/src/test_cynthion.rs
new file mode 100644
index 00000000..4530b8c4
--- /dev/null
+++ b/src/test_cynthion.rs
@@ -0,0 +1,88 @@
+use packetry::backend::cynthion::{CynthionDevice, CynthionUsability, Speed};
+use packetry::capture::{create_capture, CaptureReader, EndpointId, EndpointTransferId};
+use packetry::decoder::Decoder;
+
+use anyhow::{Context, Error};
+use futures_lite::future::block_on;
+use nusb::transfer::RequestBuffer;
+
+const TRANSFER_LENGTH: usize = 0x1000;
+
+fn main() {
+    test().unwrap();
+}
+
+fn test() -> Result<(), Error> {
+    // Create capture and decoder.
+    let (writer, mut reader) = create_capture()
+        .context("Failed to create capture")?;
+    let mut decoder = Decoder::new(writer)
+        .context("Failed to create decoder")?;
+
+    // Open analyzer device.
+    let analyzer = CynthionDevice::scan()
+        .context("Failed to scan for analyzers")?
+        .iter()
+        .find(|dev| matches!(dev.usability, CynthionUsability::Usable(..)))
+        .context("No usable analyzer found")?
+        .open()
+        .context("Failed to open analyzer")?;
+
+    // Start capture.
+    let (packets, stop_handle) = analyzer
+        .start(Speed::High,
+               |err| err.context("Failure in capture thread").unwrap())
+        .context("Failed to start analyzer")?;
+
+    // Open test device on AUX port.
+    let test_device = nusb::list_devices()
+        .context("Failed to list USB devices")?
+        .find(|dev| dev.vendor_id() == 0x1209 && dev.product_id() == 0x000A)
+        .context("Test device not found")?
+        .open()
+        .context("Failed to open test device")?;
+    let test_interface = test_device.claim_interface(0)
+        .context("Failed to claim interface 0 on test device")?;
+
+    // Read some data from the test device.
+    println!("Starting read from test device");
+    let buf = RequestBuffer::new(TRANSFER_LENGTH);
+    let transfer = test_interface.bulk_in(0x81, buf);
+    let completion = block_on(transfer);
+    completion.status.context("Transfer from test device failed")?;
+    println!("Read {} bytes from test device", completion.data.len());
+    assert_eq!(completion.data.len(), TRANSFER_LENGTH);
+
+    // Stop analyzer.
+    stop_handle.stop()
+        .context("Failed to stop analyzer")?;
+
+    // Decode all packets that were received.
+    for packet in packets {
+        decoder.handle_raw_packet(&packet)
+            .context("Error decoding packet")?;
+    }
+
+    // Look up the endpoint we're interested in and count payload bytes.
+    let bytes_captured = bytes_on_endpoint(&mut reader)
+        .context("Error counting captured bytes on endpoint")?;
+    println!("Captured {}/{} bytes of data read from test device",
+             bytes_captured, TRANSFER_LENGTH);
+    assert_eq!(bytes_captured, TRANSFER_LENGTH as u64);
+
+    Ok(())
+}
+
+fn bytes_on_endpoint(reader: &mut CaptureReader) -> Result<u64, Error> {
+    // Endpoint IDs 0 and 1 are special (used for invalid and framing packets).
+    // The first normal endpoint in the capture will have endpoint ID 2.
+    let endpoint_id = EndpointId::from(2);
+    // We're looking for the first and only transfer on the endpoint.
+    let ep_transfer_id = EndpointTransferId::from(0);
+    let ep_traf = reader.endpoint_traffic(endpoint_id)?;
+    let ep_transaction_ids = ep_traf.transfer_index.target_range(
+        ep_transfer_id, ep_traf.transaction_ids.len())?;
+    let data_range = ep_traf.transfer_data_range(&ep_transaction_ids)?;
+    let data_length = ep_traf.transfer_data_length(&data_range)?;
+    Ok(data_length)
+}