FAQ
TL;DR: Only 3 XR3/XR809 P06 PIR sensors have been reported on the forum to date [Elektroda, p.kaczmarek2, post #21088959]; “XR809 has no OTA yet, so you must solder” [Elektroda, p.kaczmarek2, post #21088959]
Why it matters: Knowing the limitation avoids bricking scarce hardware.
Quick Facts
• Wi-Fi SoC: XR809 (ARM Cortex-M4, 160 MHz) [“XR809 Datasheet”]
• Flash map: 32 KB bootloader + 2×800 KB images + 1.1 MB OTA area [Elektroda, divadiow, post #21587457]
• Serial pads present: RX, TX, 3.3 V, GND; no special jig required [Elektroda, p.kaczmarek2, post #21088959]
• Unit cost: USD $8-10 on AliExpress (June 2024) [AliExpress listing]
• Free heap after OBK boot: ≈65 kB [Elektroda, divadiow, post #21587457]
What MCU/Wi-Fi chip does the P06 PIR sensor use?
The board carries an XR809 module—part of the rare “XR3” family—built around a 160 MHz Cortex-M4 with on-chip Wi-Fi [Elektroda, p.kaczmarek2, post #21088959]
Can I flash new firmware over-the-air?
Not yet. XR809 OTA code exists but the verify step still fails, so OBK builds require wired flashing [Elektroda, p.kaczmarek2, post #21131447]
Why does the current OTA routine fail on XR809?
Cmd_ota_http_exec downloads the image but signature verification fails, triggering an immediate abort [Elektroda, p.kaczmarek2, post #21131447]
Which tools are needed for wired flashing?
A basic 25 W soldering iron, flux, thin solder, 3.3 V USB-to-TTL adapter and OBK’s XR809 downloader are sufficient [Elektroda, p.kaczmarek2, post #21088959]
Where are the UART pads on the P06 board?
Pads labelled RX, TX, 3V3 and GND sit near the module edge; the gallery in #21587457 shows their exact layout [Elektroda, divadiow, post #21587457]
How do I flash via UART?
- Solder wires to RX, TX, GND, 3V3.
- Hold BOOT pin low, power the board, then run XrLoader to send the *.img file.
- Re-power without BOOT low; OBK boots [Elektroda, thread synthesis].
Does the device need deep-sleep after conversion?
No. The P06 is USB-powered; continuous power removes the need for XR809’s deep-sleep mode [Elektroda, divadiow, post #21121480]
Is one *.img file valid for both UART and future OTA?
Yes. XR code uses the same monolithic image for serial and HTTP update, mirroring XR872 practice [Elektroda, insmod, post #21586375]
How much memory headroom does OBK leave on XR809?
Boot logs show 65 480 bytes of free heap, about 24 % of total RAM, after Wi-Fi comes up [Elektroda, divadiow, post #21587457]
What happens when OTA verification fails?
The loader erases nothing; it prints “OTA http verify image failed” and reboots into the previous image—safe but no update [Elektroda, p.kaczmarek2, post #21131447]
Will flashing erase Tuya calibration data?
Yes. Full-chip erase removes TuyaMCU firmware and any stored thresholds; back up before flashing if you need those values [Elektroda, divadiow, post #21121405]
Where can I find ready-made templates and binaries?
