Fix for udp receive reconnect

aleph/modules/msp-osd.nix

@@ -18,10 +18,13 @@ with lib; let
       cols = ${toString cfg.osdCols}
       refresh_rate_hz = ${toString cfg.refreshRateHz}
       coordinate_frame = "${cfg.coordinateFrame}"
+      char_aspect_ratio = ${toString cfg.charAspectRatio}
+      pitch_scale = ${toString cfg.pitchScale}
 
       [serial]
       port = "${cfg.serialPort}"
       baud = ${toString cfg.baudRate}
+      auto_record = ${boolToString cfg.autoRecord}
 
       # Input mappings for extracting telemetry from Elodin-DB components
       [inputs.position]
@@ -130,6 +133,40 @@ in {
       '';
     };
 
+    charAspectRatio = mkOption {
+      type = types.float;
+      default = 1.5;
+      description = ''
+        Character aspect ratio (height/width) for horizon line rendering.
+        HD OSD systems like Walksnail Avatar use ~12x18 pixel characters (ratio 1.5).
+        This compensates for non-square characters so the horizon tilt angle
+        matches the actual aircraft roll angle.
+
+        Common values:
+        - 1.5: Walksnail Avatar, DJI HD (default)
+        - 2.0: Standard SD analog OSD
+        - 1.0: Square characters (no compensation)
+      '';
+    };
+
+    pitchScale = mkOption {
+      type = types.float;
+      default = 5.0;
+      description = ''
+        Pitch scale in degrees per row for the artificial horizon.
+        Lower values = more sensitive pitch response (horizon moves more per degree).
+        Should be calibrated to match camera vertical FOV for accurate overlay.
+
+        Formula: pitch_scale ≈ camera_vertical_fov / osd_rows
+        Example: 90° VFOV / 18 rows ≈ 5° per row
+
+        Common values:
+        - 5.0: ~90° VFOV camera (default, good for Walksnail Avatar)
+        - 6.0: ~108° VFOV camera
+        - 4.0: ~72° VFOV camera (narrower FOV)
+      '';
+    };
+
     serialPort = mkOption {
       type = types.str;
       default = "/dev/ttyTHS7";
@@ -142,6 +179,16 @@ in {
       description = "Serial baud rate";
     };
 
+    autoRecord = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Automatically start DVR recording on the VTX when msp-osd starts.
+        Uses MSP2_COMMON_SET_RECORDING command (Walksnail Avatar compatible).
+        Only applies when running in serial mode.
+      '';
+    };
+
     extraArgs = mkOption {
       type = types.listOf types.str;
       default = [];

aleph/modules/udp-component-receive.nix

@@ -51,6 +51,17 @@ in {
       description = "Enable verbose logging";
     };
 
+    timestampMode = mkOption {
+      type = types.enum ["sender" "local" "monotonic"];
+      default = "sender";
+      description = ''
+        Timestamp mode for received components:
+        - sender: Use timestamp from broadcaster (default)
+        - local: Use local wall-clock time
+        - monotonic: Use Linux monotonic clock
+      '';
+    };
+
     extraArgs = mkOption {
       type = types.listOf types.str;
       default = [];
@@ -76,7 +87,8 @@ in {
         ExecStart = let
           filterArgs = concatMapStringsSep " " (f: "--filter ${f}") cfg.filter;
           verboseArg = optionalString cfg.verbose "-v";
-        in "${cfg.package}/bin/udp-receive --db-addr ${cfg.dbAddr} --listen-port ${toString cfg.listenPort} ${filterArgs} ${verboseArg} ${concatStringsSep " " cfg.extraArgs}";
+          timestampArg = "--timestamp-mode ${cfg.timestampMode}";
+        in "${cfg.package}/bin/udp-receive --db-addr ${cfg.dbAddr} --listen-port ${toString cfg.listenPort} ${timestampArg} ${filterArgs} ${verboseArg} ${concatStringsSep " " cfg.extraArgs}";
         Restart = "always";
         RestartSec = 5;
         StandardOutput = "journal";

aleph/template/flake.nix

@@ -124,6 +124,13 @@
         # refreshRateHz = 20.0;
         # osdRows = 18;
         # osdCols = 50;
+
+        # Horizon display calibration:
+        # charAspectRatio = 1.5;    # Character height/width ratio (1.5 for Walksnail Avatar)
+        # pitchScale = 5.0;         # Degrees per row (~camera_vfov / osd_rows)
+
+        # Auto-recording (Walksnail Avatar):
+        # autoRecord = true;        # Start VTX recording when service starts
       };
 
       # UDP Component Broadcast service - broadcasts component data to other flight computers
@@ -145,10 +152,11 @@
       # services.udp-component-receive = {
       #   enable = true;
       #   listenPort = 41235;               # UDP port to listen on
-      #   # autostart = true;                # Set to false to configure but not auto-start
+      #   # autostart = true;               # Set to false to configure but not auto-start
       #   # filter = ["target.world_pos"];  # Only accept specific components (empty = all)
       #   # dbAddr = "127.0.0.1:2240";      # Elodin-DB address to write to
-      #   # verbose = false;                 # Enable verbose logging
+      #   # timestampMode = "sender";       # Timestamp mode: "sender", "local", or "monotonic"
+      #   # verbose = false;                # Enable verbose logging
       # };
     };
     # sets up two different nixos systems default and installer

fsw/msp-osd/README.md

@@ -40,10 +40,13 @@ port = 2240
 rows = 18
 cols = 50
 refresh_rate_hz = 20.0
+char_aspect_ratio = 1.5  # Walksnail Avatar/DJI HD character aspect ratio
+pitch_scale = 5.0        # Degrees per row (~90° VFOV camera)
 
 [serial]
 port = "/dev/ttyTHS7"
 baud = 115200
+auto_record = false  # Set true to start VTX recording on service start
 
 # Position from world_pos indices 4,5,6
 [inputs.position]
@@ -155,6 +158,30 @@ For Walksnail Avatar connection on Aleph:
    cargo run -- --mode serial --serial-port /dev/ttyTHS7
    ```
 
+## Auto Recording
+
+The msp-osd service can automatically start DVR recording on the Walksnail Avatar VTX when the service starts. This is useful for ensuring all flights are recorded without manual intervention.
+
+To enable auto-recording, set `auto_record = true` in the `[serial]` section of your config:
+
+```toml
+[serial]
+port = "/dev/ttyTHS7"
+baud = 115200
+auto_record = true
+```
+
+Or via NixOS module:
+
+```nix
+services.msp-osd = {
+  enable = true;
+  autoRecord = true;
+};
+```
+
+This sends the `MSP2_COMMON_SET_RECORDING` command to the VTX during service initialization. The command is compatible with Walksnail Avatar VTX systems.
+
 ## Debugging on Aleph
 
 When deployed via NixOS, the msp-osd service runs in serial mode by default. For debugging:

fsw/msp-osd/config.toml

@@ -18,10 +18,39 @@ refresh_rate_hz = 20.0
 # Use "ned" when connecting to real aviation hardware with standard conventions.
 coordinate_frame = "enu"
 
+# Character aspect ratio (height/width) for horizon line rendering.
+# HD OSD systems like Walksnail Avatar use ~12x18 pixel characters (ratio 1.5).
+# This compensates for non-square characters so the horizon tilt angle
+# matches the actual aircraft roll angle.
+#
+# Common values:
+#   1.5 - Walksnail Avatar, DJI HD (default)
+#   2.0 - Standard SD analog OSD
+#   1.0 - Square characters (no compensation)
+char_aspect_ratio = 1.5
+
+# Pitch scale in degrees per row for the artificial horizon.
+# Lower values = more sensitive pitch response (horizon moves more per degree).
+# Should be calibrated to match camera vertical FOV for accurate overlay.
+#
+# Formula: pitch_scale ≈ camera_vertical_fov / osd_rows
+# Example: 90° VFOV / 18 rows ≈ 5° per row
+#
+# Common values:
+#   5.0 - ~90° VFOV camera (default, good for Walksnail Avatar)
+#   6.0 - ~108° VFOV camera
+#   4.0 - ~72° VFOV camera (narrower FOV)
+pitch_scale = 5.0
+
 [serial]
 port = "/dev/ttyTHS7"
 baud = 115200
 
+# Automatically start DVR recording on the VTX when msp-osd starts.
+# Uses MSP2_COMMON_SET_RECORDING command (Walksnail Avatar compatible).
+# Only applies when running in serial mode.
+auto_record = false
+
 # Input mappings define how to extract OSD telemetry from Elodin-DB components.
 # Each mapping specifies a component name and the array indices for each value.