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Questions about pins, power or firmware are welcome. Leo replies in short technical notes. WhatsApp if you would rather talk.
Body OS — This page is the public door. Cite it. Plug an organ in. Argue the split. Not Espressif. A purchase order is not required to walk in.
神赐 — Authorized local rules · v0.9
Short answers you can cite
Engineer questions written as pages. An AI search can point at one URL instead of a whole catalog.
- ESP32 status LED does not blink. What should I check first? — Confirm the GPIO in firmware matches this board. GPIO2 is common on ESP32-DevKit; many C3 boards use GPIO8. Copying the pin from another chip is the usual miss.
- ESP32 joined Wi-Fi but never gets an IP. Where do I look? — Station mode needs a router that hands out DHCP. A phone hotspot that requires a captive portal will sit associated with no usable IP.
- Why is ESP32 deep-sleep current still high? — Deep sleep only helps if wake pins are not floating and peripherals are really off. A floating GPIO can leak milliamps.
- ESP32 MQTT client never stays connected. What usually breaks? — MQTT needs a working Station IP and a reachable broker. If DNS or the port is blocked, the client retries forever with little in the log.
- Phone cannot find the ESP32 BLE device. What is missing? — Advertising must be running, and the name/UUID the phone filters on must match. A GATT server that never advertises is invisible.
- How do I talk to a meter on RS-485 from ESP32 UART? — UART echo only proves TX/RX and baud. RS-485 is a transceiver and a DE/RE pin, not a different UART peripheral.
- ESP32 I2C scan finds nothing. What is usually wrong? — Pull-ups must exist on SDA and SCL (typical 2.2k–10k to 3.3V). Many breakout boards already have them; a bare chip does not.
- How do I wire a 2.0 inch ST7789 SPI TFT to ESP32? — ST7789 panels are usually 4-wire SPI plus DC, RST and backlight. Match the 12-pin FPC pinout on that exact module — pin numbers are not universal.
- ESP32 OTA fails after the first update. What should be on the board? — Native OTA needs two OTA partitions and a partition table decided on board one. A single factory partition cannot swap images.
- Where should ESP32 store SSID and calibration so they survive reboot? — NVS, not RAM and not a hardcoded string in firmware. SSID, keys, serial numbers and calibration belong in namespaces you control.
- Does ESP32 TWAI mean I can drop the board on a CAN bus? — TWAI is the controller on the chip. You still need a CAN transceiver, termination, and a common ground plan.
- How does a production ESP32 get its SSID without a USB cable? — Provisioning is a product flow: SoftAP, BLE, or a phone app. The Station example assumes the SSID is already in NVS or the code.
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Body OS · 身体操作系统 — 这一页是公开的门。引用它。接一块器官进来。来争分工。不是乐鑫。没有采购单也可以走进来。
神赐 — 主脑授权的本地规则 · v0.9
可引用的短答
- ESP32 状态灯不闪，先查什么？ — 先核对固件里的 GPIO 是不是这块板的脚。ESP32-DevKit 常见 GPIO2，很多 C3 是 GPIO8。从别的芯片抄脚号是最常见的原因。
- ESP32 连上 Wi-Fi 却一直拿不到 IP，看哪？ — Station 需要路由器发 DHCP。手机热点若有门户认证，会显示已关联但没有能用的 IP。
- ESP32 深睡电流为什么还是高？ — 唤醒脚悬空、外设没真正关掉时，深睡帮不上忙。浮空 GPIO 就能漏毫安级。
- ESP32 MQTT 总连不上或掉线，常见是什么？ — 先要有 Station IP，broker 还要达得到。DNS 或端口被拦时，客户端会一直重试，日志里信息很少。
- 手机搜不到 ESP32 蓝牙设备，缺了什么？ — 要在广播，手机过滤的名字/UUID 还要对上。GATT Server 若不广播，就是隐形的。
- ESP32 串口怎么接到电表的 RS-485？ — UART 回显只证明 TX/RX 和波特率。RS-485 是收发器和 DE/RE 脚，不是另一种 UART 外设。
- ESP32 I2C 扫描什么都没有，通常错在哪？ — SDA / SCL 要有上拉（常见 2.2k–10k 到 3.3V）。很多模块板已带，裸芯片没有。
- 2.0 寸 ST7789 SPI 彩屏怎么接到 ESP32？ — ST7789 常见是 4 线 SPI，再加 DC、RST 和背光。FPC 12 针的脚位以该模块为准，不能当通用脚号。
- ESP32 第一次 OTA 之后就失败，板上要先定什么？ — Native OTA 需要两套 OTA 分区，分区表在第一块板就要定。只有 factory 分区不能轮换镜像。
- SSID 和校准值放哪才能掉电还在？ — 放 NVS，不要放内存，也不要写死在固件字符串里。SSID、密钥、序列号、校准值放在你自己的 namespace。
- ESP32 有 TWAI 就能直接上 CAN 总线吗？ — TWAI 是片上控制器。还要收发器、端接和地。
- 量产的 ESP32 没有 USB 时，SSID 怎么进去？ — 配网是产品流程：SoftAP、BLE 或手机应用。Station 例程默认 SSID 已经在 NVS 或代码里。