diff --git a/README.md b/README.md
index aebe2b6..bc97d94 100644
--- a/README.md
+++ b/README.md
@@ -7,14 +7,17 @@ GPIO22 读人体红外（PIR）模块 OUT：每次检测到运动开始，屏幕
 | 项目 | 说明 |
 |------|------|
 | 板子 | CYD ESP32-2432S028R |
-| 模块 | 三脚人体红外感应（VCC / GND / OUT），如 HC-SR501 / HC-SR505 / AM312 等 |
+| 模块 | 三脚小型人体红外（卖家常写 mini SR501，实际多为 **HC-SR505**） |
+| 供电 | **3.3V**（本工程已实测可用） |
 | 输出 | **GPIO22** |
 
+> 大圆头带电位器的是 HC-SR501，接线相同；大模块更稳妥用 5V。本仓库默认按小模块 + 3.3V 写。
+
 ### 接线
 
 | 模块 | CYD |
 |------|-----|
-| VCC | 优先 **5V**（HC-SR501 等大模块）；仅明确标 3.3V 的小模块用 **3.3V** |
+| VCC | **3.3V** |
 | GND | **GND** |
 | OUT / S / DO | **GPIO22** |
 
@@ -24,13 +27,13 @@ GPIO22 读人体红外（PIR）模块 OUT：每次检测到运动开始，屏幕
 
 - `MOTION` / `IDLE`：当前是否感应到人
 - `hold` + 进度条：本次连续有人时长（约 0～5s 满格）
-- `OUT HIGH/LOW` 与 `act=`：原始电平与有效电平 —— **挥手时 OUT 应变，不变就是供电/接线问题**
+- `OUT HIGH/LOW` 与 `act=`：原始电平与有效电平 —— 挥手时 OUT 应变 HIGH
 
 注意：
 
-- 多数 PIR 上电后需 **约 30～60 秒** 预热才稳定
-- 确认 OUT 接到 **GPIO22**（不是 21 背光），共地
-- 模块有灵敏度/延时电位器时，灵敏度先拧到最大
+- 上电后约 **30～60 秒** 预热，此前可能无反应或乱跳
+- OUT 接 **GPIO22**（勿接 21 背光），必须共地
+- 小模块一般无灵敏度旋钮；检测距离大约 3m 量级
 
 ## 操作
 
diff --git a/firmware/README.md b/firmware/README.md
index 2b90767..133c4c0 100644
--- a/firmware/README.md
+++ b/firmware/README.md
@@ -3,7 +3,7 @@
 目录：[`cyd/`](cyd/)
 
 板子：**CYD ESP32-2432S028R**（ILI9341）  
-功能：人体红外 PIR（GPIO22）计数 + SoftSPI 触控 + LVGL（同 tftest / btntest）
+功能：小型人体红外 SR505/mini SR501（GPIO22、3.3V）计数 + SoftSPI 触控 + LVGL
 
 ## 刷写
 
diff --git a/firmware/cyd/VERSION.txt b/firmware/cyd/VERSION.txt
index 2076979..1d02c4c 100644
--- a/firmware/cyd/VERSION.txt
+++ b/firmware/cyd/VERSION.txt
@@ -1,8 +1,8 @@
 name: CYD Human IR / PIR (cyd)
-git: a7854de
+git: 6226f0d
 date: 2026-10-23
 board: ESP32-2432S028R (ILI9341)
-features: SoftSPI touch, LVGL, PIR OUT on GPIO22 motion count+1
+features: SoftSPI touch, LVGL, SR505/mini PIR OUT GPIO22 @3.3V motion count+1
 flash_size: 4MB
 offsets:
   0x1000  bootloader.bin
@@ -12,5 +12,5 @@ offsets:
 sha256:
   bootloader.bin  3D234A7471F67B013686DABD4DEE7C1FA915C9928463616A94BC9297ACF1ABF8
   boot_app0.bin   F94C5D786A7A8FAB06AC5D10E33BF37711A6697636DC037559EA19CC410A17F0
-  firmware.bin    CA8FBB88050BC2284EFDDBF3ECC711A6539D4F3829994017812A30C0E2E6B057
+  firmware.bin    A870E56D4391E361A9FF6F73AA522D6ED2826937AE2565B50A9F5AA9D36D37CA
   partitions.bin  148B959CBFF1C38AA8E1D5C0BA9D612C54997B945E56A63F41223EEF650653A1
diff --git a/firmware/cyd/firmware.bin b/firmware/cyd/firmware.bin
index 7a625e1..d47cf60 100644
Binary files a/firmware/cyd/firmware.bin and b/firmware/cyd/firmware.bin differ
diff --git a/firmware/cyd/meta.json b/firmware/cyd/meta.json
index b0db7e1..c150a34 100644
--- a/firmware/cyd/meta.json
+++ b/firmware/cyd/meta.json
@@ -1,7 +1,7 @@
 {
   "boardId": "esp32-2432s028",
   "name": "CYD Human IR",
-  "summary": "PIR human infrared module on GPIO22: each motion start increments count",
-  "description": "SoftSPI touch + LVGL. VCC/GND/OUT->GPIO22. Auto polarity. Motion edge +1, hold bar, touch Reset clears.",
-  "tags": ["pir", "human-infrared", "gpio22", "touch", "lvgl", "counter"]
+  "summary": "Small PIR (SR505/mini SR501) on GPIO22 @ 3.3V: motion-start count +1",
+  "description": "SoftSPI touch + LVGL. VCC 3.3V / GND / OUT->GPIO22. Float INPUT, idle LOW active HIGH. Motion edge +1, hold bar, Reset clears.",
+  "tags": ["pir", "sr505", "human-infrared", "gpio22", "3.3v", "touch", "lvgl", "counter"]
 }
diff --git a/firmware/export_from_build.ps1 b/firmware/export_from_build.ps1
index 69bad5f..5604550 100644
--- a/firmware/export_from_build.ps1
+++ b/firmware/export_from_build.ps1
@@ -41,7 +41,7 @@ $lines = @(
   "git: $git",
   "date: $date",
   "board: ESP32-2432S028R (ILI9341)",
-  "features: SoftSPI touch, LVGL, PIR OUT on GPIO22 motion count+1",
+  "features: SoftSPI touch, LVGL, SR505/mini PIR OUT GPIO22 @3.3V motion count+1",
   "flash_size: 4MB",
   "offsets:",
   "  0x1000  bootloader.bin",
diff --git a/include/pins.h b/include/pins.h
index a052674..d1e6cf9 100644
--- a/include/pins.h
+++ b/include/pins.h
@@ -10,7 +10,7 @@
 #define CYD_TOUCH_CLK  25
 #define CYD_TOUCH_CS   33
 
-// 人体红外感应模块 OUT → GPIO22（VCC→3.3V 或 5V 视模块，GND→GND）
+// 小型人体红外（SR505 / mini SR501）OUT → GPIO22；VCC→3.3V，GND→GND
 #define PIR_PIN 22
 
 #define SCREEN_WIDTH  240
diff --git a/src/pir.cpp b/src/pir.cpp
index 2f8c4ec..2b27fa5 100644
--- a/src/pir.cpp
+++ b/src/pir.cpp
@@ -71,7 +71,7 @@ void pir_init() {
       g_idle_level == HIGH ? "HIGH" : "LOW",
       g_active_level == HIGH ? "HIGH" : "LOW", high_n);
   Serial.println(
-      "PIR tip: many modules need 5V VCC; warm-up ~30s; watch OUT on screen");
+      "PIR tip: SR505/mini@3.3V OK; warm-up ~30s; OUT HIGH on motion");
 }
 
 bool pir_poll_detect() {