Please tell me how to change the a02yyuw mode.
Norio.Kai 2026-05-01 11:09:31 27 Views2 Replies I purchased and am using three a02yyuw devices. It might be a coincidence, but all three devices I purchased will not respond unless I include mySerial.write(0x55) in the code. Is it possible to change this mode to automatic mode?
It sounds like your devices are currently set to a mode where they expect a wake-up or sync byte (like 0x55) before they’ll respond, which is why adding mySerial.write(0x55) makes them work consistently. This is actually pretty common with certain serial-based modules—they stay in a kind of “listening” state until they detect that specific trigger.
If all three of your a02yyuw units behave the same way, it’s unlikely to be a coincidence and more likely a firmware or default configuration behavior. Some variants don’t truly support a fully automatic mode unless you switch their operating mode via specific commands or hardware pin settings (if available). You might want to:
Double-check the datasheet for any mention of “active” vs “passive” modes
Look for configuration commands that toggle continuous output
Verify if there’s a hardware pin that controls the mode (sometimes labeled MODE, EN, etc.)
If none of those options are documented, it may simply be that your batch is locked into this triggered mode.
Also, if you’re working on naming or organizing multiple device configs or projects around this, you could use tools like generate name here to quickly come up with clear identifiers—it helps a lot when managing several similar devices.
Hope that helps—curious if anyone else has managed to force these into auto mode without the 0x55 trigger.
Dahlia.Sanchez Thank you for your confirmation and comments.
However, I was having trouble because the datasheet doesn’t mention whether it’s active or passive, and there are no jumpers on the device. As you say, I suppose that’s just how it is. I look forward to your continued support.
