DHT11 / AM2302 Sensor Board PlanDHT11 / AM2302 温湿度小板计划

Starting Point起点

这块 DHT11 / AM2302 温湿度小板很小：30 mm x 14 mm，三针 3V3 / DATA / GND，一个单总线传感器接口。刚看任务时很容易觉得它只是“接个传感器”，真正做起来才会发现细节都藏在小地方。

The DHT11 / AM2302 breakout is tiny: 30 mm x 14 mm, three pins, and one single-wire sensor interface. At first it looks like a simple sensor hookup. The useful details hide in the small decisions.

任务书里写了尺寸、接口、电源、上拉、电缆长度、采样周期、固件读取和焊后验证。这些都不炫，但每一项都会影响焊好后能不能稳定读到温湿度。

The task brief covered size, connector, power, pull-up, cable behavior, sampling interval, firmware readout, and post-solder verification. None of those are flashy, but each one can affect whether the sensor reads reliably.

Small Boards Can Still Fail小板也会出问题

Small boards fail in very ordinary ways: pin order reversed, pull-up value chosen lazily, sensor read too soon after power-on, sampling interval too short, or cable length making the data edge messy. Those problems look small on paper and cost real time on the bench.

小板最常见的问题也很普通：引脚顺序反了，上拉阻值随便选，传感器上电后马上读，采样间隔太短，线太长导致 DATA 边沿变差。这些问题纸面上很小，上板以后很吃时间。

So the note treats the board as a small interface task. The goal is to keep the requirement, hardware choice, and STM32 verification connected.

所以这篇笔记把它当成一个小接口任务来写：需求、硬件选择和 STM32 验证要连起来。

Points Already Clear In The Task Brief任务书里已经明确的点

• PCB size: 30 mm x 14 mm.
• Connector: PZ2.54 angled 3-pin header.
• Pin definition: 3V3 / DATA / GND.
• Communication: single-wire bus.
• Onboard peripherals: pull-up resistor, power decoupling, optional signal damping / filtering.
• Resistor/capacitor package: maximum 0603.
• Mounting: one M2 screw positioning hole.
• Power: prefer 3.3 V.
• Verification: breadboard pre-check first, then MCU verification after soldering.

• PCB 尺寸：30 mm x 14 mm。
• 接口：PZ2.54 弯针 3P。
• 接口定义：3V3 / DATA / GND。
• 通信方式：单总线。
• 板载外围：上拉电阻、电源去耦、可选信号阻尼 / 滤波。
• 阻容封装：最大 0603。
• 固定：一个 M2 螺丝定位孔。
• 供电：优先 3.3 V。
• 验证：可先面包板预验证，再焊后单片机验证。

Sampling And Verification采样和验证

AM2302 / DHT22 is fussy about timing, and that fuss belongs in the task plan. After power-on, wait at least 2 seconds before reading, and keep the read interval no shorter than 2 seconds. During verification, serial output is only the first check. The better check is to move a hand close, breathe toward the sensor, watch whether temperature and humidity change reasonably, and leave it running for several minutes to see whether failures repeat.

AM2302 / DHT22 对时间要求比较烦，但这类烦正是应该写进任务计划的地方。上电后至少等 2 秒再读，读取间隔不要小于 2 秒。验证时不只看串口有没有数字，还要看手靠近、吹气后温湿度有没有合理变化，并连续跑几分钟观察是否频繁失败。

这听起来很基础，但很多硬件调试时间就是被这些基础问题吃掉的。

Files文件

• DHT11 / AM2302 breakout plan PDF
• Juanyun thermal hardware project

Why I Kept This Note记下来

The useful thing about this board is the small loop it forces: define the connector, choose pull-up and decoupling, respect power-on wait, read at the right interval, and verify with an MCU instead of only trusting the datasheet.

这个小板有价值，是因为它逼着人走完一个小循环：接口定义，上拉和去耦选择，上电等待，按正确间隔读取，再用 MCU 验证，而不是只相信数据手册里那几行参数。