Samstag, 9. September 2017

Just some things about the Adafruit TPL5110

That's it how the TPL5110 is now in use

In order to build a wheatherstation, to have a better overview over the temperatures in winter, I bought the TPL5110 from Adafruit. This should allow me to shut down the whole system, which includes a RTC, a ADS1115 with analog sensors (winddirection, moisture and illumination), and a DHT11, if there are no measurements token.

The first thing I had a problem with were the peaks every I/O Pin of the ESP puts out when it is turned on. This peak was able to activate the TPL, which shuted down the ESP. So the ESP wasn't able to work. First I tried to use a capacitor. It worked very well, to prevent the TPL from the peaks, but its long discharge time caused that the time of the TPL wasn't set correctly, and every wakeup time was different from the others.

So I tried to put a diode from the "Done" pin to ground which helped a bit to stabilize the times of the TPL. But I still had problems to start the IC. Sometimes, it won't start, and sometimes, it won't wokr after the first measurement. I figured out that there were not such problems if I hold the VDD and GND pin to GND of my power supply. So I thought there must be some problems caused by capacitance. Now, I desoldered the capacitor of the TPL5110 breakout-board - and it still works quiet well!

To bypass Boot-Mode-Errors of the ESP8266 (which are often caused by an unstable power supply) I added a 10 mikrofarad capacitor between the "DRV" pin of the TPL and ground.

So for short, what I did:
- desolder 1µF capacitor from TPL5110 beakout
- add a 1N4001 diode from Drive to ground
- add a 10µF capacitor from DRV to ground

Excuse me please for my english spelling and thanks to exp-tech who provide electronics from Adafruit in Germany!