Tuya ZY-TH01ProCB3S_v1.4 Temp & Humidity Sensor Firmware Programming

Question

I have a couple of Tuya ZY-TH01ProCB3S_v1.4 temp & humidity sensors with LCD display; see the attached pictures. I tried to use CloudCutter on the first one and that seemed to go well and I managed to reflash it OTA with what I now assume is rubbish. So, I have been trying to reflash it using a...

divadiow · Answer

I have a feeling the RX/TX pads on the back of these are for the TuyaMCU and not the CB3S. I recall as much from this version https://www.elektroda.com/rtvforum/topic4095818.html

You probably won't want to remove the LCD so you'd need to angle something in to get to the pads on CB3S

Dnomis77 · Answer

Hi, thanks. I have tried using the top 2 RHS pins on the CB3S module directly also, but it didn't behave any differently. It never seems to reset, and seems to have a path to power for the LCD even if I apply power at the CB3S pins.

divadiow · Answer

hmm yes. TuyaMCU is also known to get in the way of flashing so often rx and or tx needs to be isolated from the TuyaMCU. This can be done by removing the CB3S completely or severing a PCB trace then repairing it later. The LCD on these makes CB3S removal quite a chore. Your wires definitely short to CB3S RX/TX and they cross with your USB-TTL RX->TX and TX->RX?

You may be able to hold the TuyaMCU is reset mode too I think I've seen reported, but I haven't had a device where that's been possible yet. More difficult if you can't even see the chip and then if it's pins are known.

Dnomis77 · Answer

I've not tried removing a surface mount board before, it was hard enough trying to solder to it!
I removed the wires from direct connection at the CB3S TX/RX and yes, I tried lots of combinations of TX - TX, TX -RX etc and baud rates, I saw someone posted that they had to use 15000000 so will try that tomorrow.
Not sure how to go about removing the CB3S heat up and cut the join with a scalpel? Solder Pump? Presumably I only need to remove the 3.3v and Tx/ Rx lines

divadiow · Answer

I was thinking hot air gun removal after desoldering the LCD, but that's probably not an option.

But actually, look, the RX/TX on CB3S do look to go those headers on the back. I hadn't spotted that. Looks like they each have a little trace breaking out to the TuyaMCU? maybe?

Section of green PCB labeled MCU_TX, MCU_RX with solder joints and red arrows

Maybe it'll just be a case of severing the CB3S's RX at that little junction so TuyaMCU can't transmit stuff and get in the way.

How are you powering your device btw? external 3.3v power supply with common grounds to USB-TTL or powering whole thing from USB-TTL 3.3v or 5v with LDO?

Added after 2 [minutes]:

that assumes these two come off CB3S RX/TX

View of PCB segment labeled for AAA 1.5V battery placement

Dnomis77 · Answer

I have tried powering it via just the TTL converter, via batteries and via one of those USB to 3v battery eliminators. The circuit board looks like multi layered so not easy to trace where those 2 go, ill have another look in the morning. I don't have a hot air gun suitable for SMD removal so that option is out. And I really didn't want to remove the LCD unless I have to.

Tuya ZY-TH01ProCB3S_v1.4 Temp & Humidity Sensor Firmware Programming

Post #1

Post #2

Post #3

Post #4

Post #5

Post #6

Post #7

Didn't find an answer? Ask Artificial Intelligence

Topic summary