diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e886185
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,21 @@
+# OS images are intentionally kept out of git.
+os/*.7z
+os/*.img
+os/*.img.*
+os/*.xz
+os/*.zip
+
+# Local audio/debug captures.
+*.wav
+*.aiff
+*.flac
+
+# C/C++ build outputs.
+build/
+cmake-build-*/
+*.o
+*.obj
+*.exe
+*.dll
+*.dylib
+*.so
diff --git a/README.md b/README.md
index fc89b92..3f28f19 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,23 @@
 # mic
 
-wifi를 사용하는 임베디드 마이크 제작 프로젝트
\ No newline at end of file
+Orange Pi Zero 2W 기반 Wi-Fi 라발리에 마이크 송신기와 Mac 수신/믹서 프로젝트입니다.
+
+```text
+USB lavalier -> Orange Pi Zero 2W -> 2.4/5 GHz Wi-Fi router -> Mac mixer
+```
+
+## Structure
+
+- `client/`: Orange Pi에서 실행하는 마이크 송신기
+- `server/`: Mac에서 실행하는 UDP 수신/믹서
+- `os/`: Orange Pi OS 이미지 보관 위치
+- `docs/`: 보드 세팅과 스트리밍 실행 가이드
+
+## Current Direction
+
+- OS: official Orange Pi Debian 12 Bookworm Server, Linux 6.1
+- Language: C++
+
+## Docs
+
+- `docs/01-orange-pi-os.md`
diff --git a/docs/01-orange-pi-os.md b/docs/01-orange-pi-os.md
new file mode 100644
index 0000000..27b5805
--- /dev/null
+++ b/docs/01-orange-pi-os.md
@@ -0,0 +1,67 @@
+# Orange Pi Zero 2W OS setup
+
+## Recommended image
+
+Use the official Debian 12 Bookworm server image for Orange Pi Zero 2W:
+
+```text
+orangepizero2w_1.0.0_debian_bookworm_server_linux6.1.31.7z
+```
+
+Orange Pi's Zero 2W wiki lists Debian 12 Bookworm with Linux 6.1 as supported, and its Linux 6.1 driver table marks Wi-Fi, Type-C USB2.0, TF card boot, and related board features as OK.
+
+Official references:
+
+- https://www.orangepi.org/orangepiwiki/index.php/Orange_Pi_Zero_2W
+- https://www.orangepi.org/html/hardWare/computerAndMicrocontrollers/service-and-support/Orange-Pi-Zero-2W.html
+
+## Flashing
+
+1. Download the image into `os/`.
+2. Extract the `.7z` file to get the `.img`.
+3. Flash the `.img` to the microSD with Balena Etcher, Raspberry Pi Imager, or another verified imaging tool.
+4. Mount the flashed boot/root partition and configure first-run Wi-Fi before inserting it into the Orange Pi.
+
+## Headless Wi-Fi first boot
+
+On the flashed SD card, find:
+
+```text
+/boot/orangepi_first_run.txt.template
+```
+
+Copy it to:
+
+```text
+/boot/orangepi_first_run.txt
+```
+
+Then set the Wi-Fi fields. `os/orangepi_first_run.example.txt` contains a local example for Korea region code `KR`.
+
+The important values are:
+
+```text
+FR_net_change_defaults=1
+FR_net_ethernet_enabled=0
+FR_net_wifi_enabled=1
+FR_net_wifi_ssid='YOUR_WIFI_SSID'
+FR_net_wifi_key='YOUR_WIFI_PASSWORD'
+FR_net_wifi_countrycode='KR'
+```
+
+## First login
+
+For official Debian/Ubuntu Orange Pi images, the usual default accounts are:
+
+```text
+orangepi / orangepi
+root     / orangepi
+```
+
+Change the password on first login.
+
+```bash
+passwd
+sudo passwd root
+```
+
diff --git a/os/README.md b/os/README.md
new file mode 100644
index 0000000..ad3fd25
--- /dev/null
+++ b/os/README.md
@@ -0,0 +1,26 @@
+# OS image storage
+
+Put the Orange Pi Zero 2W OS image files here, but do not commit them.
+
+Recommended first image:
+
+```text
+orangepizero2w_1.0.0_debian_bookworm_server_linux6.1.31.7z
+```
+
+Why this one:
+
+- Debian 12 Bookworm server image keeps the transmitter small and headless.
+- Linux 6.1 is listed by Orange Pi as supporting Wi-Fi, Type-C USB2.0, TF card boot, and the usual board peripherals on Zero 2W.
+- A server image gives us a small, headless baseline for the future C++ transmitter.
+
+Official pages:
+
+- https://www.orangepi.org/orangepiwiki/index.php/Orange_Pi_Zero_2W
+- https://www.orangepi.org/html/hardWare/computerAndMicrocontrollers/service-and-support/Orange-Pi-Zero-2W.html
+
+Notes:
+
+- Use the Zero 2W-specific image only. A generic ARM64 Debian or Ubuntu image will usually miss the board kernel/DTB/Wi-Fi pieces.
+- The official download page may redirect to external storage such as Google Drive.
+- Keep `.7z`, `.img`, `.xz`, and similar files in this folder locally; `.gitignore` excludes them.
diff --git a/os/orangepi_first_run.example.txt b/os/orangepi_first_run.example.txt
new file mode 100644
index 0000000..fa3efb0
--- /dev/null
+++ b/os/orangepi_first_run.example.txt
@@ -0,0 +1,19 @@
+# Copy /boot/orangepi_first_run.txt.template to /boot/orangepi_first_run.txt,
+# then use values like these before the first boot.
+
+FR_general_delete_this_file_after_completion=1
+
+FR_net_change_defaults=1
+FR_net_ethernet_enabled=0
+FR_net_wifi_enabled=1
+
+FR_net_wifi_ssid='YOUR_WIFI_SSID'
+FR_net_wifi_key='YOUR_WIFI_PASSWORD'
+FR_net_wifi_countrycode='KR'
+
+FR_net_use_static=0
+FR_net_static_ip='192.168.0.50'
+FR_net_static_mask='255.255.255.0'
+FR_net_static_gateway='192.168.0.1'
+FR_net_static_dns='8.8.8.8 1.1.1.1'
+