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

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By Arvindsa
#75000 I have been programming an ESP8266 on a custom board. The DTR pin is pulled up to 3.3 via 10K resistor and also a tactile switch SW4 is connected to it (Circuit attached). The switch connects it to GND when pressed. I was able to program it couple of times but after I tried a minor soldering attempt on DTR pin, I am getting the following behavior.
1. When i reset, The existing program works, The Voltage level on DTR is pulled up correctly to 3.3V andd at button press, it drops down to GND and ESP can detect the button press
2. When i start to program it, ESP Resets but i Get
warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed
error: espcomm_upload_mem failed.

3. using logic analyzer, i captured the following, After RST goes low, DTR goes low but when released DTR stays at 1.7v instead of 3.3.
screenshot_1.png

screenshot2.png

New Doc 2018-03-30_1.jpg


Do let me know is this a normal behavior and how to fix it.
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By frans eilering
#95689 I had the same errors. Sometimes I could program it, sometimes not.
I found a solution

be sure your arduino sketch does NOT contain a serial.begin....
If so, upload a blink example to the arduino without a serial.begin and then select the genericESP8266 module to upload your sketch.

to program
-VCC off
-GPIO0 to GND
-VCC on
-GPIO0 to VCC
PROGRAM IT


In normal operation, leave GPIO0 not connected