FAQ
TL;DR: You can safely flash the “2 MB” OpenBeken ESP-IDF image onto 4 MB or 8 MB ESP8266 boards—just keep the matching partition table; after PR #1707, OTA now works again on all sizes, handling images up to ~1 MB [Elektroda, insmod, post #21596825]
Quick Facts
• Supported flash sizes: 1 MB / 2 MB / 4 MB / 8 MB (common ESP8266 limits) [Elektroda, divadiow, #21595385; #21596199]
• Max OTA image size in ESP8266-RTOS SDK: 1 048 576 bytes (1 MB) [Espressif OTA Guide]
• Default OBK partition map (2-4 MB): 2× 0xE0000 OTA slots + 0x30000 LFS + NVS [Elektroda, boot log, #21595385]
• Fix that restored OTA on ≥4 MB boards: commit 2025-07-03, “partition layout corrected” [Elektroda, insmod, post #21596825]
• PWM console spam removed by updating duty only on change (25 ms loop disabled) [Elektroda, p.kaczmarek2, post #21596997]
Which ESP8266 flash sizes does the new OpenBeken build recognise?
Bootloader reports and works with 1 MB, 2 MB, 4 MB and 8 MB SPI flash chips [Elektroda, divadiow, #21595385; #21596199].
Can I flash the 2 MB image on a 4 MB or 8 MB module?
Yes. The image occupies the first 1 MB OTA slot; the extra space is unused unless you adjust the partition CSV before build [Elektroda, insmod, post #21596138]
What partition layout should I use?
Keep two 0xE0000 OTA slots starting at 0x10000 and 0xF0000, plus NVS and optional LFS. Use the provided partitions-2mb.csv for 2-4 MB, or enlarge offsets for 8 MB [Elektroda, insmod, post #21596825]
Why did OTA fail earlier and how was it fixed?
Older images wrote the second OTA slot outside valid flash range on bigger chips, triggering Exception 28. The July-03 patch realigned offsets and OTA now reboots cleanly [Elektroda, divadiow, #21596199; insmod, #21596825].
Does OTA work from Tasmota?
Not directly. Tasmota uses the NON-OS SDK, while OpenBeken uses ESP8266-RTOS SDK; cross-OTA requires a custom RTOS-format binary and a special stub per Espressif’s migration guide [Elektroda, insmod, post #21597062]
What is the maximum firmware size I can upload?
With the default map each OTA slot is 0xE0000 (917 504 bytes); ESP8266-RTOS SDK further limits proven images to 1 MB [Espressif OTA Guide].
How can I use the spare space on an 8 MB board?
Re-generate the partition CSV to give LFS several megabytes (e.g., 6 MB) for web assets or logs; firmware size stays the same [Elektroda, p.kaczmarek2, post #21597058]
Is gzip compression for WebApp files possible?
Yes. Serve pre-compressed .gz files and add the header Content-Encoding: gzip; LFS can first look for name.ext.gz before name.ext [Elektroda, insmod, #21597649; p.kaczmarek2, #21597813].
Why did PWM spam the console every 25 ms?
Old driver updated duty unconditionally; the fix triggers an update only on value change, removing the flood [Elektroda, insmod, #21596825; p.kaczmarek2, #21596997].
How is UART RX implemented in the RTOS build?
A simple task polls uart_read_bytes() and feeds a ring buffer; an interrupt version crashes on large bursts [Elektroda, insmod, post #21596138]
Does deep-sleep work?
Timer deep-sleep enters low-power mode but fails to wake on test boards; GPIO wake is not yet implemented in the SDK port [Elektroda, insmod, post #21597042]
Has Wi-Fi stability improved?
Yes. First-connect and reconnect bugs were cleared; modules stay online without resets for hours [Elektroda, insmod, #21596138; DeDaMrAz, #21596140].
Are there plans for UI or WebApp changes?
Developers discuss cleaning legacy fields, adding gzip uploads, and enlarging on-device WebApp for 8 MB modules [Elektroda, DeDaMrAz, #21597496; p.kaczmarek2, #21597272].
