docs: update camera feature documentation

docs/en/source/camera_devices/6_benchmark/othertools.md

@@ -1,5 +1,52 @@
 # Other Tools
 
+## firmware_update_tool
+
+`firmware_update_tool` upgrades device firmware or writes preset files from the ROS 2 command line. Before upgrading, make sure the device connection is stable. When multiple devices are connected, specify the serial number to avoid updating the wrong device.
+
+Show help:
+
+```bash
+ros2 run orbbec_camera firmware_update_tool -- --help
+```
+
+Upgrade firmware for one device:
+
+```bash
+ros2 run orbbec_camera firmware_update_tool -- \
+--serial_number <SN> \
+--firmware_path /path/to/firmware.bin
+```
+
+Write a preset file:
+
+```bash
+ros2 run orbbec_camera firmware_update_tool -- \
+--serial_number <SN> \
+--preset_path /path/to/preset.bin
+```
+
+For batch updates, `--serial_number` accepts comma-separated values. Add `--continue_on_error` if later devices should still be processed after one device fails.
+
+```bash
+ros2 run orbbec_camera firmware_update_tool -- \
+--serial_number SN1,SN2 \
+--firmware_path /path/to/firmware.bin \
+--continue_on_error
+```
+
+## Frame Timestamp CSV Logging
+
+When `enable_frame_timestamp_csv` is enabled, the camera node records Color and Depth frame timestamp data to a CSV file. This is useful for frame synchronization, publish latency, and timestamp debugging.
+
+```bash
+ros2 launch orbbec_camera gemini_330_series.launch.py \
+enable_frame_timestamp_csv:=true \
+frame_timestamp_csv_file:=/tmp/frame_timestamp.csv
+```
+
+The CSV includes SDK frame index, hardware frame number, sensor timestamp, device/global/system timestamp, arrival timestamp, publish timestamp, inter-frame delta values, and SDK delay fields.
+
 ## Ob_benchmark tool
 
 > The goal of this tool is to benchmark the performance of various OrbbecSDK_ROS2 camera configurations. The benchmark results depend on the camera and settings used.(Currently only works with ROS2 Humble)
@@ -49,4 +96,4 @@ ros2 run orbbec_camera ob_benchmark_node
 The output data files will be stored in the ob_benchmark folder with filenames like `0.csv`, `1.csv`, ..., 19.csv. For example:
 
 - `0.csv` contains data from the `ob_benchmark_0.launch.py` configuration.
-- `1.csv` contains data from the `ob_benchmark_1.launch.py` configuration.
+- `1.csv` contains data from the `ob_benchmark_1.launch.py` configuration.