FAQ
TL;DR: Adding the single command tuyaMcu_sendQueryState drops post-reboot “zero-reading” incidents from 100 % to 0 % [Elektroda, lars4, post #21169864] As p.kaczmarek2 notes, "tmSensor is only for battery powered devices" [Elektroda, p.kaczmarek2, post #21171036]
Why it matters: One extra line stabilises five environmental channels without hardware changes.
Quick Facts
• Default UART speed: 9 600 baud; auto-detect works on 2 MB flashes [Elektroda, p.kaczmarek2, post #21171036]
• Reboot-to-ready time: ~53 s on CB3S module [Elektroda, io2345, post #21600458]
• DHT20 temp/humidity accuracy: ±0.3 °C / ±2 % RH (Typical, Sensirion datasheet)
• HGS1000 VOC sensor uses 3.3 V UART, 9 600 baud [Elektroda, p.kaczmarek2, post #21177061]
• CB3S GPIO pin drive ≤12 mA; use transistor switch for 35 mA buzzer [Elektroda, io2345, post #21593564]
How do I make OpenBeken display sensor data immediately after power-up?
Insert tuyaMcu_sendQueryState at the end of autoexec.bat. It polls all Tuya DPIDs and fills channels at boot, eliminating zeros [Elektroda, lars4, post #21169869]
Which baud rate should I set for the TuyaMCU driver?
Most AirBox units talk at 9 600 baud. Add tuyaMcu_setBaudRate 9600 or let auto-detect handle it on 2 MB flashes [Elektroda, p.kaczmarek2, post #21171036]
Is `tmSensor` needed for this mains-powered AirBox?
No. tmSensor targets battery devices; leave it out to avoid log spam [Elektroda, p.kaczmarek2, post #21171036]
What sensors are inside the AirBox?
A DHT20 handles temperature and humidity [Elektroda, lars4, post #21173538] VOCs come from an HGS1000 module, confirmed by the manufacturer [Elektroda, divadiow, post #21174757]
How can I trigger a buzzer when limits are exceeded?
- Wire the buzzer through an NPN transistor to GPIO 8.
- Set GPIO 8 role to Relay and map it to Channel 8.
- Add an alarm loop:
alias ALARM_ON setChannel 8 1
alias ALARM_OFF setChannel 8 0
again: delay_s 10 if $CH1>580||$CH2>890||$CH3>50||$CH4>200||$CH5>1200 then ALARM_ON else ALARM_OFF goto again [Elektroda, io2345, post #21595628]
Why did my multi-line IF script fail?
OpenBeken’s parser accepts single-line if … then … else … only. Break logic into chained single-line tests or use the compact form above [Elektroda, p.kaczmarek2, post #21595612]
What’s the maximum current I can source from a CB3S GPIO?
Approximately 12 mA. Driving a 35 mA buzzer directly risks damage; always add a transistor switch [Elektroda, io2345, post #21593564]
Can I read DHT20 directly instead of via TuyaMCU?
Yes—assign I²C pins and start the DHT driver, but you’ll lose Tuya-side compensation algorithms. Most users stay with TuyaMCU for simplicity [Elektroda, p.kaczmarek2, post #21177061]
How do I reduce Wi-Fi power draw?
Run PowerSave 1; it toggles the RF sleep mode and shaves roughly 25 % off idle current (approx. 12 mA to 9 mA, lab test) [OpenBeken Docs].
Edge case: values disappear after several hours—why?
The TuyaMCU can stop pushing updates. Schedule a periodic tuyaMcu_sendQueryState every 15 s with addRepeatingEvent 0 0 15 tuyaMcu_sendQueryState [Elektroda, p.kaczmarek2, post #21171036]
How long does a software reboot take?
Logged boot time is about 53 seconds from command to valid sensor readings on CB3S firmware v1.0.1 [Elektroda, io2345, post #21600458]
Can I flash without desoldering the CB3S?
Yes. lars4 flashed via serial pads in-circuit; original firmware restored fine afterward [Elektroda, lars4, post #21169787]
