ESP8266 Community Forum

- Wed Mar 16, 2016 4:01 am #43276 Hi Mattia,

My Wemos boards have been running for, in some cases, many weeks now, waking from deep sleep every 15mins without problems. I connect D0 to RST with a ~500R. I did experiment with using using 4K7. This did not work and resulted in what looks like the same situation you are facing where the deep sleep ends, a line of garbage appears on serial monitor, but the sketch does not run. I then tried 2K2, which worked well on 5V USB power, but did not work on ~3.8V battery power (3xAAA NiMH). Finally i used 510R which runs fine at either voltage.

I have also experimented with light sleep and modem sleep. I have not been able to achieve low current consumption with light sleep. In fact i found it used more current than modem sleep. In my circuit i need to monitor sensors every 2~5ms, so cannot light sleep for longer periods, which might explain my findings.

- Wed Mar 16, 2016 5:25 am #43283 Hi Paul,
I've put a 330R between GPIO16 and RST (reset every 5s) and it worked for half an hour before hanging.
It's more than the usual minute or two without any resistor.
I doubled with 660R and it hanged almost immediately.
I'm trying again with 660R.
Powering with USB now.

I received the same suggestion in the adafruit forum by another member, he suggested a 470R resistor.
In the meantime thanks, you two are the first talking about a resistor between GPIO16 and RST, everywhere else is all about pullup to GPIO0 and 2 and pulldown on 15. For some it seems to be sufficient, for me it wasn't.

- Wed Mar 16, 2016 5:42 am #43285 Hello,

why use a resistor?
From the Adafruit Datasheet of the Huzzah Feather Board:
GPIO #16 can be used to wake up out of deep-sleep mode, you'll need to connect it to the RESET
pin

I connected it directly. My Huzzah Feather Board is working now for four weeks. It wakes up every 15 Minutes and is sending a UDP-Packet to the PC. If i control it, i haven't missed a packet until now.

regards
Dieter

- Wed Mar 16, 2016 8:42 am #43300 The reason of having resistor in series between GPIO16 and RST is simply required because while in deepSleep(), the GPIO16 is providing a real HIGH level output, preventing to do an external reset by other external devices such a CH340, therefore not able to do an upload while sleeping.

The issue of hanging on RES is probably a simple power supply issue occurring when WiFi is returning ON.