Tasmota temperature sensors

I've been doing a little home automation with Home Assistant recently and this involved putting temperature sensors in every room. I started out with some ugly stripboard SHT11 based things but they were unreliable and inaccurate.

During a Banggood sale I managed to pick up some Wemos 'shields' with an SHT30 temperature/humidity sensor so I converted all my sensors over to these. Tidier but still a bare circuit board with power LEDs lighting the room at night.

I fiddled around in OpenSCAD and came up with a fairly decent 3D printed enclosure and now have eight sensors dotted around my house, including the shed. This design leaves the SHT30 sticking out in free air with a 'baffle' to separate it from the rest of the device. Even so the temperature readings are massively effected by heat soak from the ESP8266 and quite inefficient LDO on the board. I've now put this on Thingiverse.

To fix the heat soak you need to connect D0 to RST on the D1 mini with a short piece of wire and enable deep sleep so they draw (and waste) much less power. In Tasmota this needs two console commands...

TelePeriod 10

DeepSleepTime 300

...the 'TelePeriod' means it sends data 10s after connecting to WiFi and 'DeepSleepTime' means it sleeps until the next five minute interval on the clock. If you're copying this example don't issue the commands until you're happy with the Tasmota configuration. The short wake time makes it a pain to issue changes later.

Now they send decent sensor readings, reliably.

Solar charging ESP-Now BATMAN prototype 2

After over two weeks continuous running my first prototype of the solar charged prototype proved itself with a 2W panel. So I spent a chunk of time designing the next iteration in EasyEDA and ordered five PCBs from JLCPCB in China.

I've taken a small gamble with this design as I haven't built it on breadboard first and have added a number of new features.

• Thermal protection for the 18650 cells, a feature available but omitted from the MCP73871 evaluation board. They will now only charge in temperatures of 0-50C, which is a default safe option. I don't feel this will kick in often in the UK except perhaps on a very sunny but cold morning however to omit this feature would be slightly negligent.
• Replacement of the INA219 current monitors with a simple resistor ladder to measure supply voltage after the charge controller with the ESP8285.
• Connection of the MCP73871 status pins to the ESP8285 rather than indicator LEDs.
• A microSD socket for optional file storage.

This is quite a simple project compared to the people making their own small board computers or things based on FPGAs but it's only my second ever manufactured PCB. All the pins on the ESP8285 board are in use, although in principle IO0 which has a button attached for putting it into programming mode could be doubled up with for something else so long as it defaulted to a pullup.

Instead of going straight to the final run of boards I'd like to test these five before ordering more. I made absolutely no effort to keep it compact so even if no changes are needed I'll still move things around and tidy it up before the final order.

Once these arrive I'm hoping the extra efficiency of the PAM2301 regulator will make a 1W panel viable in the UK but if not, 2W panels aren't overly huge.