diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8016c3fe..c51e71e8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,7 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/).
 ### Added
 
 - Transparent LoRa radio over USB CDC-ACM (VID `1209`, PID `5741`)
-- COBS-framed postcard binary protocol (8 commands, 6 responses)
+- COBS-framed fixed-size LE binary protocol (8 commands, 6 responses)
 - Radio configuration: frequency, bandwidth, spreading factor, coding rate, TX power
 - Continuous RX mode with RSSI/SNR per packet
 - Single-shot TX with optional per-packet config override
diff --git a/DESIGN.md b/DESIGN.md
index 574f4825..172511f9 100644
--- a/DESIGN.md
+++ b/DESIGN.md
@@ -97,8 +97,8 @@ keep, but never prematurely.
 
 | Decision | Choice | Why |
 |---|---|---|
-| USB framing | COBS + postcard | Compact, `no_std` native, battle-tested |
-| Serialization | postcard + serde | Zero-alloc binary codec, perfect for embedded |
+| USB framing | COBS | Compact, `no_std`, zero-overhead frame delimiting |
+| Serialization | Fixed-size LE | Every field at a known offset. No varints, no surprises |
 | Async runtime | Embassy | De facto standard for async embedded Rust |
 | Display | Radio status dashboard | Freq, BW, SF, packet counts, RSSI/SNR |
 | Boot behavior | Idle until host commands | Host-driven principle |
diff --git a/README.md b/README.md
index e7d013c0..fdebc329 100644
--- a/README.md
+++ b/README.md
@@ -23,10 +23,9 @@ and gets out of the way. No mesh logic, no protocol opinions, no config files.
 
 ## Protocol
 
-DongLoRa speaks a binary protocol over USB CDC-ACM: COBS-framed
-[postcard](https://postcard.jamesmunns.com/) messages. 8 commands,
-6 response types — everything you need to configure the radio,
-transmit, and receive.
+DongLoRa speaks a binary protocol over USB CDC-ACM: COBS-framed,
+fixed-size little-endian messages. 8 commands, 6 response types —
+everything you need to configure the radio, transmit, and receive.
 
 See **[docs/PROTOCOL.md](docs/PROTOCOL.md)** for the complete wire format
 specification with worked examples.
diff --git a/examples/donglora.py b/examples/donglora.py
index 04888915..8ca43d73 100644
--- a/examples/donglora.py
+++ b/examples/donglora.py
@@ -1,7 +1,7 @@
 """DongLoRa host library — connect, configure, send/receive LoRa packets.
 
 This is a minimal helper for the example scripts. It implements the
-DongLoRa USB protocol (COBS-framed postcard) just enough to be useful.
+DongLoRa USB protocol (COBS-framed fixed-size LE) just enough to be useful.
 See docs/PROTOCOL.md for the full specification.
 """
 # /// script