ESP8266 Community Forum

- Mon Oct 19, 2015 7:04 am #31724 Hi there,
I've been having some interesting issues with this and was hoping someone could point me in the right direction - I am currently setup on a breadboard,using the power from the FTDI board for the ESP8266.
1. have flashed the ESP8266 with nodemcu using a FTDI usb serial cable, then put gpio0 high and reset (pulled out the usb cable from the FTDI and plugged back in) and the ESP8266 is then recognised by Esplorer, allowing me to upload a program as init.lua . I then connect gpio0 and gpio2 to LED's each with 1k resistors and the program works great (currently on/off switching of 2 LED's using a webpage and a static ip) but when I reset the ESP8266 (remove usb cable from FTDI) there is no longer communication with Esplorer or the router. It seems to default to gpio2 being high and gpio0 low?
2. I have also tested only flashing the ESP8266 , establishing communication with esplorer and then resetting (with no program upload) and the same communication loss with esplorer happens, so i'm guessing it's a pin configuration issue with the ESP8266?

Has anyone had a similar issue? Be great if someone could point out if I'm doing something blatantly silly here
- currently RST is floating- does this need to be pulled high?
-Is a decoupling capacitor between VCC and GND needed?
- other advice?

thanks in advance!

- Mon Oct 19, 2015 2:19 pm #31765 When you program the ESP-01, GPIO0 must be high and GPIO2 must be low, or the device will not let you upload a firmware. Then, just after the firmware is uploaded, the device will run your code, irregardless of GPIO0 and GPIO2. However, if you reboot the device, the you must be sure again that GPIO is not high and GPIO2 is not low, or it will wait for a firmware upload again.

- Mon Oct 19, 2015 2:25 pm #31767

GPIO0 must be high and GPIO2 must be low

Small correction : it is the reverse, GPIO2=HIGH and GPIO0=LOW for serial upload.

- Mon Oct 19, 2015 2:33 pm #31768

- currently RST is floating- does this need to be pulled high?
-Is a decoupling capacitor between VCC and GND needed?

Although Espressif mentioned that there is an internal PullUp on RES and it can be left floating, many people faced an issue with that because the internal PullUp is too weak, simply touching the pin with a finger make the RES resetting. So, I strongly suggest to add an external one about 10K to avoid such issue, not only with fingers but any noisy environment.
For the decoupling capacitor, yes, it is important to have some as near as possible of the ESP power pins, something like 100uF or 470uF.

Last edited by martinayotte on Mon Oct 19, 2015 7:12 pm, edited 1 time in total.