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User avatar
By PetrSkoda
#91018 Hello guys, I have a question. When I connect NodeMCU v2 with ESP8266 I hear that windows connection sound and I even can see that COM in device manager and in Arduino ide. I can connect to that ESP with Putty (i see only a black screen). But when I connect it, that built-in led isn't blinking and I can't upload code to that ESP. Do you have any suggestions? Thank you.
User avatar
By QuickFix
#91030 First things first:
  • Remove all (USB to) COM-ports, so you can be absolutely certain you have the correct port
  • Connect the NodeMCU board directly to a USB port on your PC (not through a USB hub) and verify its COM-port in device manager
  • Create a new profile in PuTTY, settings: serial, COM X (X is your port), 74880 Baud (yes, this is not a typo)
  • Optionally you can save this profile as "ESP8266 debug" or something similar, for future use
  • Press the OK-button: you might get some gibberish on the screen
  • Now press the RST (RESET) button on NodeMCU board: if everything is okay you should see something similar to this:
    Code: Select all ets Jan  8 2013,rst cause:2, boot mode:(3,7)

    load 0x4010f000, len 3584, room 16
    tail 0
    chksum 0xb0
    csum 0xb0
Tell us what you are getting.
User avatar
By Buzzardbait
#91053 I'm suddenly having a similar problem. Also using Putty at 74880baud. I get:
ets Jan 8 2013,rst cause:2, boot mode:(7,7)

waiting for host

Windows says everything is ok with the silLabs com6 port.

The Arduino IDE message when trying to upload is:
esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header

ok, so I swapped out the NodeMCU for another one and sketch downloaded fine and serial monitor is fine. The other ESP8266 was mounted and soldered onto a board so it's either a problem with the ESP8266 or a connection problem on the board interfering with serial RxTx.
User avatar
By Buzzardbait
#91054 I quickly found the problem. In my application I'm using SPI to communicate with a peripheral so there were HSCLK, HMOSI, HMISO and HCS connections to the NodeMCU via a 5V/3.3V translator. With no inputs applied the D8/GPIO15/TXD2/HCS pin was being pulled high by the level translator. Had to GND the 5V CS input to the translator and then the NodeMCU downloaded just fine.
This leads to several interesting questions:
1. Why does HCS interfere with GPIO1/TXD0 and GPIO3/RXD0 since I think these are the ones used for basic serial IO including sketch uploading?
2. Does this also mean NodeMCU(as slave) device select is active HIGH(this would be contrary to Arduino boards active low)?