Tiny ESP32 board

[pythoncoder]

I have bought a couple of these. The board is highly compact, has 4MB of SPIRAM and works with official and Loboris ports with SPIRAM support in the latter.



Further images, including a schematic, on the Tindie link above.

A small issue is with the optional HTU21D temperature and humidity chip. While it works perfectly it is warmed by the adjacent ESP32 module, which affects its readings. This is probably inevitable on such a tiny board. I think the solution is to put the ESP32 into sleep mode for a period before taking a reading. Otherwise buy without the HTU21D and use an external HTU21D breakout (e.g. from Adafruit).

[rcolistete]

Thanks, pity that only 3 are available now, I need about 20.

Another option of ESP32 with 4MB PSRAM, not too tiny but the 1.3" OLED + 2 buttons are useful :
ESP32-Wrover 4MB PSRAM + 1.3" OLED + 2 buttons + microUSB + microSD
Same, on Tindie :
https://www.tindie.com/products/lspoplo ... ino-32-sd/
I don't know if the build quality is good. Planning to buy it, does someone has experience with this board ?

[Bonnom]

I just did a power consumption measurement with the esp32 in idle without running any code and my usb power meter couldn't detect any power draw. This means the power usage is 0.01 amps or 10mA if the USB powermeter is correct.
However the power consumptions increases to 50~80mA when the board is connected to a wifi access point.
You might be able to drastically reduce the power consumption by only enabling the wifi periodically.

[OutoftheBOTS_]

Do u know that Station mode on a wifi router uses less power than Access point mode

[pythoncoder]

@rcolistete Have you asked the vendor about lead times? I found him helpful and communicative.

@Bonnom I did my testing of the temperature sensor without initiating a WiFi connection. If you look at the datasheet for the HTU21D it recommends milling slots in the PCB to avoid the chip being warmed by adjacent components. On such a tiny board the designer didn't have room for this. I think accurate measurements are best done by using sleep mode or with a separate breakout board.

[rcolistete]

@rcolistete Have you asked the vendor about lead times? I found him helpful and communicative.

My need for about 20 ESP32 with 4MB PSRAM will be confirmed in the following weeks. Then I'll conctact the vendor. Thanks.

[Bonnom]

@rcolistete Have you asked the vendor about lead times? I found him helpful and communicative.

@Bonnom I did my testing of the temperature sensor without initiating a WiFi connection. If you look at the datasheet for the HTU21D it recommends milling slots in the PCB to avoid the chip being warmed by adjacent components. On such a tiny board the designer didn't have room for this. I think accurate measurements are best done by using sleep mode or with a separate breakout board.

That is too bad! Probably the voltage regulator (probably a AMS1117) and the esp32 use most of the power. If only the esp32 generated the heat you could have removed the metal shield and put a heatsink on it. Than it would dump the heat in the air instead of the pcb.

When using WiFi you probably would even need to use deepsleep mode even if the temperature sensor had a milled slot in the pcb. The esp32 can get quite hot when using wifi, this will warm up the close surrounding by a couple degrees.