[Tuya Smart] Lichuang EDA Tuya version low power temperature and humidity meter +584242A

Updated on February 9th:

The PCB has been completed, and overall I am quite satisfied with it. The power consumption is also relatively low. It has been used for more than a week after the battery is fully charged, and the power display is still 100%~

What is more depressing is that in this development-free version, the displays are all integers, such as 15.0 degrees Celsius, 16.0 degrees Celsius, etc., and there is no display like 15.3 at all.

I communicated with Tuya’s technical support for several days, but they were always talking about it, but they just couldn’t get to the point, that’s all, let’s just make do with it.

When welding SHT30, you need to pay attention. Do not use a heat gun. The package pad of the SHT30 I drew is elongated. Don’t worry about welding. SHT30 is much more durable than we thought!

I originally planned to make an anti-tamper switch for the base plate, but the encapsulation of the micro switch was too large, which wasted one of Liu Gong's proofing coupons. How sad! ! !

I am honored to participate in the Tuya Smart training class for the second time:)

This time I still chose the zero-code module. After all, the MCU solution still requires writing code. That is my weakness, so I won’t exploit it :)

The temperature and humidity meter designed this time is based on low power consumption . The charging IC only works when it is plugged into USB for charging, including the charging indicator light, which also works when it is plugged in.

After charging, use the battery to convert the LDO to 3.3V. The charging IC and charging indicator light on the front are cut off and no longer work.

The LDO chose HT7333-1 with a static power consumption of 1~2ua . The disadvantage is that the current is low, maybe less than 300ma. Therefore, a 100uf tantalum capacitor must be added when powering the Tuya module.

The battery is powered by two 200mah disassembled batteries, which are attached to the back of the motherboard with 3M glue when in use.

I am currently simulating the anti-tamper button with a switch. I will test how it works first. I connected the two network points of the tamper button to the M2 and M3 set screws.

If there are still proofing coupons later, I plan to make a base plate the same size as the motherboard. Use fixing screws to guide the two networks of the anti-tamper button to the base plate, then put the anti-tamper button and stick it somewhere. It will be perfect. Yes, hahaha:)