- Wed May 27, 2015 4:15 pm
#18666
The actual pullup values (or pull down) are not overly critical. 10k is a very common value but depending on the circuit and chips used they can even be 100k. In general it's best to not go below 10k (except for I2C).
When the reset pin is written as "nRST" it is just for a more descriptive name meaning that if the pin is held low it will reset. Sometimes you will see the pin name with a line above it which means the same thing. It all depends on the chip whether you need to pull a pin high or low to make it perform the function. For the ESP8266 you always want the pin to be pulled high and only when you want to reset the chip do you pull it low.
GPIO16 is directly connected to the RST pin (with RST still pulled high). When the chip comes out of deep sleep it will pull GPIO16 low and with GPIO16 connected to reset the chip will reset and turn back on. For me, that's kind of an odd way to bring a chip out of sleep but it works with this chip.
It is common to have a resistor and capacitor pair on a rest pin. This forms a RC circuit which is a delay. This is an easy way to hold the reset pin low for a little longer when the power if first applied. This gives everything extra time to "get ready" before functioning.
Double check your capacitor values you've stated, you have some "uF" and "nF" mixed up. Since the ESP modules don't have much onboard capacitance and the current draw can drastically change from very little to 200-300mA it is best to have a "reservoir" cap on the Vcc rail placed close to the module. This will help prevent voltage droop when the large current spikes happen.
The ADC can have a maximum of 1V input so you need to make sure any signal entering the ADC is no more than 1V. This is why you see a voltage divider on the NodeMCU design. (I haven't looked closely at this so someone correct me if I'm wrong).
I hope this helps.
