Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)

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By washburn_it
#92501 Hi,
some time ago I bought 2 "HiLetgo" ESP8266 (ESP-12E), one of them is used for a small solar powered weather station with a bunch of sensors.
I've set a 10 minutes deep sleep and it's working perfectly.
The other ESP8266 seems to have a problem with deep sleep.
I tried to load the same sketch as the "weather station" but with 1 minute for deep sleep, connected D0 with RST pin, it enters the deep sleep but after 1 minute I can see the blue led blinking once (it should blink when it wakes up) but it seems that is stuck at boot.
Checking with the serial monitor if I press the RST button, the ESP boots correctly (I can see some messages on the serial monitor), after the first deep sleep when it wakes up, I can just see garbage on the serial monitor and nothing else.
At that point I have to disconnect D0 from RST and reset it manually.
What should I check?
Thank you, regards.

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By btidey
#92513 1. Set your serial monitor to 74880. This will enable you to see what the 'garbage' is and help diagnose the problem. The ESP9266 starts up with serial port at 74880 but then switches to 115200 during the boot process.

2. The RST pin has a capacitor to ground to assist with generating a good power on reset. This can sometimes disrupt the wake up pulse particularly if significant resistance is included in the connection to RST. I often use the EN pin instead of the RST as the wake up input as this is a raw input with no added capacitance. Using EN works the same way unless you are using the non-volatile storage on the ESP8266 as this will be cleared by the EN pulse.