diff --git a/Production/Firmware/chu_pico.uf2 b/Production/Firmware/chu_pico.uf2
index 2e6fb16..b0df583 100644
Binary files a/Production/Firmware/chu_pico.uf2 and b/Production/Firmware/chu_pico.uf2 differ
diff --git a/README.md b/README.md
index a968698..aed2271 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,7 @@
 Features:
 * It's small, made for 15-17 inch screen.
 * Air towers are replaced with built-in ToF sensors.
+* Traditional IR Air mechanism is also provided for DIYers.
 * HID lights, of course!
 * 32 keys (upper and lower rows).
 * Follows CrazyRedMachine's RedBoard I/O protocol.
@@ -169,6 +170,20 @@ You need **4x M3*12mm screws and 4x M3 hex nuts** to fix all things.
 7x silicone anti-slip pads can be applied to the bottom side of the base to provide stability when playing.  
 <img src="doc/silicone_pad.png" width="50%">
 
+### IR Air Tower
+This is not necessary for Chu Pico. But some people may prefer the traditional IR air tower, especially when they're using Chu Pico design for a full-sized controller.
+So hereby I provide the IR air tower design, with a pair of air tower PCBs and the firmware support.
+1. First, you need to order the PCBs, the gerber file is `Production\PCB\chu_air_v*.zip`. It's for both sides of the air tower.
+2. Order the components, they're marked in the schematic. Then solder them to the PCB following the silkscreen.
+3. For left side tower, use J1 to connect to the Raspberry Pi Pico, and for the right side tower, use J2. GPIO 3 -> A, GPIO 4 -> B, GPIO 5 -> C, ADC 0 (GPIO 26) -> Right S, ADC 1 (GPIO 27) -> Left S.  
+  <img src="doc/air_tower_wiring.png" width="50%">
+4. Steps for deployment.
+  I. Enable IR air tower in the firmware (command `ir enable`), this will disable ToF.
+  II. Enable diagnostics for IR (command `ir diagnostic`).
+  III. Place the air towers and watch the output of the diagnostics, higher value means beam is received.
+  IV. Set the baseline after the towers are properly placed (command `ir baseline`).
+  V. Optionally, set the sensitivity, it's a percentage of expected change (command `ir trigger <1..100>`).
+
 ### Firmware
 * UF2 file is in `Production\Firmware` folder.
 * For the new build, hold the BOOTSEL button while connect the USB to a PC, there will be a disk named "RPI-RP2" showed up. Drag the UF2 firmware binary file into it. That's it. There's a small hole at the bottom side of the Chu Pico, it is facing right to the BOOTSEL button.
diff --git a/README_CN.md b/README_CN.md
index 2d0ce3a..1ffafc1 100644
--- a/README_CN.md
+++ b/README_CN.md
@@ -6,6 +6,7 @@
 **特性:**
 * 它很小巧，适合15-17寸屏幕。
 * 空键被 ToF 距离传感器替代。
+* 也提供了传统 IR Air 的机制供 DIY 玩家使用。
 * HID 灯光，必须的！
 * 32个按键（上下两排）。
 * 遵循 CrazyRedMachine 的 RedBoard I/O 协议。
@@ -177,6 +178,20 @@ https://github.com/whowechina/
 7x 个硅胶防滑垫可以贴在基座的底部，以提供游玩时候的稳定性。
 <img src="doc/silicone_pad.png" width="50%">
 
+### 红外空键
+Chu Pico 本身不需要红外空键。但是有些人可能用 Chu Pico 来做一个全尺寸的控制器，它们更喜欢传统的 IR 空键。
+所以我提供了 IR 空键的设计，包括一对空键 PCB 和对应的固件支持。
+1. 首先，你需要下单 PCB，Gerber 文件在 `Production\PCB\chu_air_v*.zip`。空键的两侧都需要这个 PCB。
+2. 根据原理图里的有标记，购买对应的元器件，然后按照丝印焊接到 PCB 上。
+3. 左侧空键 PCB 使用 J1 连接到 Pi Pico 主控，右侧空键 PCB 使用 J2 连接。GPIO 3 -> A, GPIO 4 -> B, GPIO 5 -> C, ADC 0 (GPIO 26) -> Right S, ADC 1 (GPIO 27) -> Left S。  
+  <img src="doc/air_tower_wiring.png" width="50%">
+4. 调试上线的过程如下：
+  I. 在固件中启用 IR 空键（命令 `ir enable`），它会自动禁用 ToF。
+  II. 启用 IR 的诊断功能（命令 `ir diagnostic`）。
+  III. 摆放两侧的空键塔，观察诊断输出，数值高代表着对应的红外光线已经对准接收器。
+  IV. 在正确摆放好空键塔后，设置基线（命令 `ir baseline`）。
+  V. 可选，设置触发灵敏度，是一个变化率的百分比值（命令 `ir trigger <1..100>`）。
+
 ### 固件
 * UF2 文件在 `Production\Firmware` 文件夹下。
 * 全新烧录的话，按住 Pico Pi 的 BOOTSEL 按钮，然后连接 USB 到 PC，会出现一个名为 "RPI-RP2" 的磁盘。将 UF2 固件二进制文件拖入即可。Chu Pico 的底部有一个小孔，它正对着 BOOTSEL 按钮。
diff --git a/doc/air_tower_wiring.png b/doc/air_tower_wiring.png
new file mode 100644
index 0000000..4ab7a89
Binary files /dev/null and b/doc/air_tower_wiring.png differ
diff --git a/firmware/src/commands.c b/firmware/src/commands.c
index 1bda8e6..87dc93b 100644
--- a/firmware/src/commands.c
+++ b/firmware/src/commands.c
@@ -260,7 +260,6 @@ static void air_baseline()
         chu_cfg->ir.base[i] = air_ir_raw(i);
         printf(" %4d", chu_cfg->ir.base[i]);
     }
-    config_changed();
     printf("\n");
 }
 
@@ -289,19 +288,26 @@ static void air_trigger(char *argv[])
 
 static void handle_ir(int argc, char *argv[])
 {
-    const char *usage = "Usage: ir <diagnostic|baseline>\n"
+    const char *usage = "Usage: ir <enable|disable|diagnostic|baseline>\n"
                         "       ir trigger <percent>\n"
                         "  percent: [1..100]\n";
     if (argc == 1) {
-        const char *commands[] = { "diagnostic", "baseline" };
+        const char *commands[] = { "enable", "disable", "diagnostic", "baseline" };
         int cmd = cli_match_prefix(commands, count_of(commands), argv[0]);
         if (cmd == 0) {
-            air_diagnostic();
+            chu_cfg->ir.enabled = true;
+            air_init();
         } else if (cmd == 1) {
+            chu_cfg->ir.enabled = false;
+        } else if (cmd == 2) {
+            air_diagnostic();
+        } else if (cmd == 3) {
             air_baseline();
         } else {
             printf(usage);
+            return;
         }
+        config_changed();
     } else if (argc == 2) {
         air_trigger(argv);
     } else {