diff --git a/Firmware/src/Messages/Composer.cpp b/Firmware/src/Messages/Composer.cpp
new file mode 100644
index 0000000..87d2428
--- /dev/null
+++ b/Firmware/src/Messages/Composer.cpp
@@ -0,0 +1,15 @@
+#include "Composer.h"
+
+bool message::composer::sendMessage(protocol::Message type,
+                                    etl::string_view content) {
+  if (content.length() > protocol::MAX_PAYLOAD_LEN) {
+    return false;
+  }
+  uint8_t length =
+      protocol::HEADER_LEN + static_cast<uint8_t>(content.length());
+  // Serial.write("HX");
+  // Serial.write(length);
+  // Serial.write(protocol::to_underlying(type));
+  // Serial.write(content.data());
+  return true;
+};
diff --git a/Firmware/src/Messages/Composer.h b/Firmware/src/Messages/Composer.h
new file mode 100644
index 0000000..469d527
--- /dev/null
+++ b/Firmware/src/Messages/Composer.h
@@ -0,0 +1,9 @@
+#pragma once
+#include "Protocol.h"
+#include <etl/string.h>
+
+namespace message {
+namespace composer {
+bool sendMessage(protocol::Message type, etl::string_view content);
+} // namespace composer
+} // namespace message
diff --git a/Firmware/src/Messages/Parser.cpp b/Firmware/src/Messages/Parser.cpp
new file mode 100644
index 0000000..d619148
--- /dev/null
+++ b/Firmware/src/Messages/Parser.cpp
@@ -0,0 +1,242 @@
+#include "Parser.h"
+
+message::parser::StateVisitor::StateVisitor(etl::byte_stream_reader &sreader)
+    : stream{sreader} {}
+
+auto message::parser::StateVisitor::operator()(state::ModeSelection) -> State {
+  if (!stream.available<uint8_t>()) {
+    return state::Invalid{};
+  }
+
+  auto mode = stream.read<uint8_t>();
+  if (!mode.has_value()) {
+    return state::Invalid{};
+  }
+
+  switch (mode.value()) {
+  case static_cast<uint8_t>(protocol::Mode::Message):
+    return state::Message{};
+  case static_cast<uint8_t>(protocol::Mode::Settings):
+    return state::Settings{};
+  case static_cast<uint8_t>(protocol::Mode::LightControl):
+    return state::LightControl{};
+  case static_cast<uint8_t>(protocol::Mode::Command):
+    return state::Command{};
+  default:
+    return state::Invalid{};
+  }
+}
+
+auto message::parser::StateVisitor::operator()(state::Message) -> State {
+  if (!stream.available<uint8_t>()) {
+    return state::Invalid{};
+  }
+
+  auto mode = stream.read<uint8_t>();
+  if (!mode.has_value()) {
+    return state::Invalid{};
+  }
+
+  switch (mode.value()) {
+  case static_cast<uint8_t>(protocol::Message::LightData):
+    return state::MessageLightData{};
+  case static_cast<uint8_t>(protocol::Message::Info):
+    return state::MessageInfo{};
+  case static_cast<uint8_t>(protocol::Message::Warning):
+    return state::MessageWarning{};
+  case static_cast<uint8_t>(protocol::Message::Error):
+    return state::MessageError{};
+  case static_cast<uint8_t>(protocol::Message::Success):
+    return state::MessageSuccess{};
+  default:
+    return state::Invalid{};
+  }
+}
+auto message::parser::StateVisitor::operator()(state::MessageLightData)
+    -> State {
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::MessageInfo) -> State {
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::MessageWarning) -> State {
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::MessageError) -> State {
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::MessageSuccess) -> State {
+  return state::Complete{};
+}
+
+auto message::parser::StateVisitor::operator()(state::Settings) -> State {
+  if (!stream.available<uint8_t>()) {
+    return state::Invalid{};
+  }
+
+  auto mode = stream.read<uint8_t>();
+  if (!mode.has_value()) {
+    return state::Invalid{};
+  }
+
+  switch (mode.value()) {
+  case static_cast<uint8_t>(protocol::Settings::SetBaud):
+    return state::SettingsSetBaud{};
+  case static_cast<uint8_t>(protocol::Settings::SetWifiPassword):
+    return state::SettingsWifiPassword{};
+  case static_cast<uint8_t>(protocol::Settings::SetWifiSSID):
+    return state::SettingsWifiSSID{};
+  default:
+    return state::Invalid{};
+  }
+}
+auto message::parser::StateVisitor::operator()(state::SettingsSetBaud)
+    -> State {
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::SettingsWifiPassword)
+    -> State {
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::SettingsWifiSSID)
+    -> State {
+  return state::Complete{};
+}
+
+auto message::parser::StateVisitor::operator()(state::LightControl) -> State {
+  if (!stream.available<uint8_t>()) {
+    return state::Invalid{};
+  }
+
+  auto mode = stream.read<uint8_t>();
+  if (!mode.has_value()) {
+    return state::Invalid{};
+  }
+
+  switch (mode.value()) {
+  case static_cast<uint8_t>(protocol::LightControl::On):
+    return state::LightControlOn{};
+  case static_cast<uint8_t>(protocol::LightControl::Off):
+    return state::LightControlOff{};
+  case static_cast<uint8_t>(protocol::LightControl::Toggle):
+    return state::LightControlToggle{};
+  case static_cast<uint8_t>(protocol::LightControl::Increase):
+    return state::LightControlIncrease{};
+  case static_cast<uint8_t>(protocol::LightControl::Decrease):
+    return state::LightControlDecrease{};
+  default:
+    return state::Invalid{};
+  }
+}
+auto message::parser::StateVisitor::operator()(state::LightControlOn) -> State {
+  if (stream.available_bytes() > 0) {
+    return state::Invalid{};
+  }
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::LightControlOff)
+    -> State {
+  if (stream.available_bytes() > 0) {
+    return state::Invalid{};
+  }
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::LightControlToggle)
+    -> State {
+  if (stream.available_bytes() > 1) {
+    return state::Invalid{};
+  }
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::LightControlIncrease)
+    -> State {
+  if (stream.available_bytes() > 1) {
+    return state::Invalid{};
+  }
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::LightControlDecrease)
+    -> State {
+  if (stream.available_bytes() > 1) {
+    return state::Invalid{};
+  }
+  return state::Complete{};
+}
+
+auto message::parser::StateVisitor::operator()(state::Command) -> State {
+  if (!stream.available<uint8_t>()) {
+    return state::Invalid{};
+  }
+
+  auto mode = stream.read<uint8_t>();
+  if (!mode.has_value()) {
+    return state::Invalid{};
+  }
+
+  switch (mode.value()) {
+  case static_cast<uint8_t>(protocol::Command::RequestLightData):
+    return state::CommandRequestLightData{};
+  case static_cast<uint8_t>(protocol::Command::EnterConsoleFlashing):
+    return state::CommandEnterConsoleFlashing{};
+  case static_cast<uint8_t>(protocol::Command::ExitConsoleFlashing):
+    return state::CommandExitConsoleFlashing{};
+  case static_cast<uint8_t>(protocol::Command::PairBluetooth):
+    return state::CommandPairBluetooth{};
+  case static_cast<uint8_t>(protocol::Command::Help):
+    return state::CommandHelp{};
+  case static_cast<uint8_t>(protocol::Command::Version):
+    return state::CommandVersion{};
+  default:
+    return state::Invalid{};
+  }
+}
+auto message::parser::StateVisitor::operator()(state::CommandRequestLightData)
+    -> State {
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(
+    state::CommandEnterConsoleFlashing) -> State {
+  if (stream.available_bytes() > 0) {
+    return state::Invalid{};
+  }
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(
+    state::CommandExitConsoleFlashing) -> State {
+  if (stream.available_bytes() > 0) {
+    return state::Invalid{};
+  }
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::CommandPairBluetooth)
+    -> State {
+  if (stream.available_bytes() > 0) {
+    return state::Invalid{};
+  }
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::CommandHelp) -> State {
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::CommandVersion) -> State {
+  return state::Complete{};
+}
+
+auto message::parser::StateVisitor::operator()(state::Complete) -> State {
+  return state::Complete{};
+}
+auto message::parser::StateVisitor::operator()(state::Invalid) -> State {
+  return state::Invalid{};
+}
+
+auto message::parser::parse(etl::byte_stream_reader &reader) -> void {
+  StateVisitor visitor{reader};
+  State state{state::ModeSelection{}};
+  while (!etl::holds_alternative<state::Invalid>(state) &&
+         !etl::holds_alternative<state::Complete>(state)) {
+    state = etl::visit(visitor, state);
+  }
+  if (etl::holds_alternative<state::Invalid>(state)) {
+    // TODO: error
+  }
+}
diff --git a/Firmware/src/Messages/Parser.h b/Firmware/src/Messages/Parser.h
new file mode 100644
index 0000000..9ecaf66
--- /dev/null
+++ b/Firmware/src/Messages/Parser.h
@@ -0,0 +1,88 @@
+#pragma once
+#include "Protocol.h"
+#include <etl/byte_stream.h>
+#include <etl/variant.h>
+
+namespace message {
+namespace parser {
+namespace state {
+struct Invalid {};
+struct ModeSelection {};
+struct Message {};
+struct MessageLightData {};
+struct MessageInfo {};
+struct MessageWarning {};
+struct MessageError {};
+struct MessageSuccess {};
+struct Settings {};
+struct SettingsSetBaud {};
+struct SettingsWifiPassword {};
+struct SettingsWifiSSID {};
+struct LightControl {};
+struct LightControlOn {};
+struct LightControlOff {};
+struct LightControlToggle {};
+struct LightControlIncrease {};
+struct LightControlDecrease {};
+struct Command {};
+struct CommandRequestLightData {};
+struct CommandEnterConsoleFlashing {};
+struct CommandExitConsoleFlashing {};
+struct CommandPairBluetooth {};
+struct CommandHelp {};
+struct CommandVersion {};
+struct Complete {};
+} // namespace state
+
+using State = etl::variant<
+    state::Invalid, state::ModeSelection, state::Message,
+    state::MessageLightData, state::MessageInfo, state::MessageWarning,
+    state::MessageError, state::MessageSuccess, state::Settings,
+    state::SettingsSetBaud, state::SettingsWifiPassword,
+    state::SettingsWifiSSID, state::LightControl, state::LightControlOn,
+    state::LightControlOff, state::LightControlToggle,
+    state::LightControlIncrease, state::LightControlDecrease, state::Command,
+    state::CommandRequestLightData, state::CommandEnterConsoleFlashing,
+    state::CommandExitConsoleFlashing, state::CommandPairBluetooth,
+    state::CommandHelp, state::CommandVersion, state::Complete>;
+
+void parse(etl::byte_stream_reader &reader);
+
+class StateVisitor {
+private:
+  etl::byte_stream_reader stream;
+
+public:
+  StateVisitor(etl::byte_stream_reader &);
+  State operator()(state::ModeSelection);
+  State operator()(state::Message);
+  State operator()(state::MessageLightData);
+  State operator()(state::MessageInfo);
+  State operator()(state::MessageWarning);
+  State operator()(state::MessageError);
+  State operator()(state::MessageSuccess);
+
+  State operator()(state::Settings);
+  State operator()(state::SettingsSetBaud);
+  State operator()(state::SettingsWifiPassword);
+  State operator()(state::SettingsWifiSSID);
+
+  State operator()(state::LightControl);
+  State operator()(state::LightControlOn);
+  State operator()(state::LightControlOff);
+  State operator()(state::LightControlToggle);
+  State operator()(state::LightControlIncrease);
+  State operator()(state::LightControlDecrease);
+  State operator()(state::Command);
+  State operator()(state::CommandRequestLightData);
+  State operator()(state::CommandEnterConsoleFlashing);
+  State operator()(state::CommandExitConsoleFlashing);
+  State operator()(state::CommandPairBluetooth);
+  State operator()(state::CommandHelp);
+  State operator()(state::CommandVersion);
+
+  State operator()(state::Complete);
+  State operator()(state::Invalid);
+};
+} // namespace parser
+} // namespace message
diff --git a/Firmware/src/Messages/Protocol.h b/Firmware/src/Messages/Protocol.h
new file mode 100644
index 0000000..7afcf2b
--- /dev/null
+++ b/Firmware/src/Messages/Protocol.h
@@ -0,0 +1,54 @@
+#pragma once
+#include <etl/type_def.h>
+#include <etl/type_traits.h>
+#include <etl/variant.h>
+#include <etl/visitor.h>
+#include <type_traits>
+
+namespace message {
+namespace protocol {
+static const uint8_t HEADER_LEN = 5;
+static const uint8_t MAX_TOTAL_LEN = 255;
+static const uint8_t MAX_PAYLOAD_LEN = MAX_TOTAL_LEN - HEADER_LEN;
+
+enum class Mode : uint8_t {
+  Message = 0x0,
+  Settings = 0x1,
+  LightControl = 0x2,
+  Command = 0x3
+};
+
+enum class Message : uint8_t {
+  LightData = 0x0,
+  Info = 0x1,
+  Warning = 0x2,
+  Error = 0x3,
+  Success = 0x5,
+};
+
+enum class Settings : uint8_t {
+  SetBaud = 0x0,
+  SetWifiPassword = 0x1,
+  SetWifiSSID = 0x2,
+};
+
+enum class LightControl : uint8_t {
+  On = 0x0,
+  Off = 0x1,
+  Toggle = 0x2,
+  Increase = 0x3,
+  Decrease = 0x4,
+};
+
+enum class Command : uint8_t {
+  RequestLightData = 0x0,
+  EnterConsoleFlashing = 0x1,
+  ExitConsoleFlashing = 0x2,
+  PairBluetooth = 0x3,
+  Help = 0x4,
+  Version = 0x5,
+};
+
+using Submode = etl::variant<Mode, Message, Settings, LightControl, Command>;
+} // namespace protocol
+} // namespace message