将 CSV 写入 SD 卡
将读数追加到文件中，以便稍后分析
将 CSV 写入 SD 卡 是 CoddyKit 上的免费 Arduino & IoT Academy 课时。 这是第 2 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 Arduino & IoT Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Arduino & IoT Academy 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
Why an SD Card?
An SD card gives your device cheap, roomy storage that survives power loss. It is perfect for keeping a long history of logged readings. 💾
Why CSV?
CSV means comma-separated values: plain text where each line is a record and commas split the fields. Spreadsheets open it instantly.
What a Row Looks Like
One log entry per line keeps things tidy. A row might pair a timestamp with a reading so each value has clear meaning later.
2026-06-25 14:03,24.7,55The SD Module
An SD card module connects over the SPI bus. You wire its MOSI, MISO, SCK, and CS pins to the matching pins on your board.
Starting the Card
Before reading or writing you must initialize the card and tell the library which pin is chip select. If it fails, the card or wiring is off.
if (!SD.begin(10)) { return; }Opening a File
You open a file by name, choosing a mode. Use FILE_WRITE to add data; it creates the file if it does not exist yet.
File f = SD.open("log.csv", FILE_WRITE);Appending, Not Overwriting
FILE_WRITE seeks to the end, so each new line is appended. Your old entries stay safe and the history keeps growing.
Writing a Line
You print fields and commas just like Serial output. End the row with println so the next entry starts on a fresh line.
f.print(temp);
f.print(",");
f.println(humidity);Always Close the File
Calling close() flushes your data and frees the file. Skip it and your last writes may never reach the card.
f.close();A Header Row
Write a header line once when the file is new, naming each column. Spreadsheets then label your charts automatically.
time,temp,humidityDon't Write Too Often
Each write costs power and time. For battery nodes, log every few seconds or minutes rather than every loop to keep the card happy.
Quick Check
What happens if you forget to close the file after writing?
Recap
Wire an SD module over SPI, open a CSV file in append mode, print comma-separated rows, and always close it. Now your readings are saved for good. ✅
常见问题解答
「将 CSV 写入 SD 卡」课时是免费的吗？
是的 — 「将 CSV 写入 SD 卡」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Arduino & IoT Academy 课程的其余内容，请升级到 CoddyKit PRO。 Arduino & IoT Academy 课程共包含 4 节课。
「将 CSV 写入 SD 卡」这节课中我会学到什么？
将读数追加到文件中，以便稍后分析 你通过在浏览器中直接运行的动手代码来练习 Arduino & IoT Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 Arduino & IoT Academy 需要有经验吗？
无需任何先前经验。CoddyKit 上的 Arduino & IoT Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 2 节课，共 4 节。
「将 CSV 写入 SD 卡」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 Arduino & IoT Academy 课中编写并运行代码吗？
能。每节 Arduino & IoT Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。
此课程中的所有课时
- 使用 NTP/RTC 获取实时时间
- 将 CSV 写入 SD 卡
- 缓冲与批量上传
- 可视化记录的数据