Buffer & Batch Uploads
Store offline and sync when WiFi returns.
Buffer & Batch Uploads is a free Arduino & IoT Academy lesson on CoddyKit — lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Arduino & IoT Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
WiFi Isn't Always There
Real devices lose their connection: the router reboots, the signal drops, the cloud blips. A good logger keeps working when the network disappears. 📶
Don't Drop Data
If you only send readings live, an outage means lost samples forever. The fix is to store offline first, then upload once the network returns.
What a Buffer Is
A buffer is a temporary holding area for data waiting to be sent. Your readings queue up there safely until an upload can happen.
Where to Buffer
For a few values, an array in RAM works. For many that must survive resets, buffer to an SD card file or flash instead.
What Batching Means
Batching means sending many readings in one request instead of one at a time. Fewer connections save power and play nicely with the cloud.
The Save-Then-Send Loop
The pattern is simple: always save a reading to the buffer, and only try to upload when WiFi is connected.
save(reading);
if (WiFi.status() == WL_CONNECTED) upload();Check the Connection
Before every upload, confirm you are online. Skipping this check makes your code hang or throw errors during an outage.
if (WiFi.status() != WL_CONNECTED) return;Send the Whole Batch
When online, package the queued readings, often as a JSON array, and POST them together in a single batch request.
POST /readings [ {...}, {...}, {...} ]Clear Only on Success
Delete buffered data only after the server confirms it. If the upload fails, keep the data and retry next time.
Watch the Memory
A growing buffer can overflow RAM. Cap its size, or write to storage, so a long outage never crashes the device.
Back Off on Failure
If uploads keep failing, wait longer between tries. This backoff saves battery and avoids hammering a struggling server. 🔋
Quick Check
When should you delete readings from your offline buffer?
Recap
Always save first, upload in batches when online, and clear the buffer only on confirmed success. Your logger now survives any outage. ✅
Frequently asked questions
Is the “Buffer & Batch Uploads” lesson free?
Yes — the full text of “Buffer & Batch Uploads” is free to read here on the web, and the Arduino & IoT Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Arduino & IoT Academy course, upgrade to CoddyKit PRO.
What will I learn in “Buffer & Batch Uploads”?
Store offline and sync when WiFi returns. You practise Arduino & IoT Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Arduino & IoT Academy?
No prior experience is required. Arduino & IoT Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Buffer & Batch Uploads” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Arduino & IoT Academy lesson?
Yes. Every Arduino & IoT Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Get Real Time with NTP/RTC
- Write CSV to an SD Card
- Buffer & Batch Uploads
- Visualize Logged Data