ESP8266 Community Forum

- Mon Jul 06, 2015 10:18 am #22585 I have several ESP-01 modules all displaying similar symptoms.

Modules operate normally for a couple days while developing, and then stop working after a power reset. Attempts to reflash firmware or read any output are futile.

The red power LED is operational and the blue tx/rx LED flashes briefly when power is applied to the module. I'm not entirely sure but it seems like the bootloader has been damaged. Is there a way to recover from these symptoms? How can I avoid this happening again in the future?

- Tue Jul 07, 2015 8:49 pm #22746

I have several ESP-01 modules all displaying similar symptoms.

Modules operate normally for a couple days while developing, and then stop working after a power reset. Attempts to reflash firmware or read any output are futile.

The red power LED is operational and the blue tx/rx LED flashes briefly when power is applied to the module. I'm not entirely sure but it seems like the bootloader has been damaged. Is there a way to recover from these symptoms? How can I avoid this happening again in the future?

More info please. What have you tried to flash, and what did you see while flashing?

Look for info on how to flash the ESP with blank512k.bin which clears it, and then try a simple example.

I've been using (abusing) the same 2 ESP-01s for over 6 months now, without bricking them.

- Wed Jul 08, 2015 3:08 am #22755 Hi kenn,

Thanks for responding. I think I found the issue as I was able to reflash all the unresponsive modules. I was using the SDK 1.00 firmware with AT .22 command set controlled by an Arduino. In the course of developing and reflashing the Arduino I would sometimes leave the ESP-01 powered on and connected to the RX/TX pins of the Arduino. These are the same pins used to flash the Arduino so I think a lot of bytes got sent to the ESP at the same time causing a soft brick.

I believe the reason I wasn't able to consistently flash succesfully before was related to the breadboard socket adapter I made for the ESP - but not 100% sure. I took that out of the equation and used wires directly from the module to the breadboard and everything is working fine. I am currently able to flash the ESP modules with the rudimentary "ESP8266 Flash Downloader" Windows program - still no luck with the NodeMCU flasher.

- Wed Jul 08, 2015 10:00 am #22774 Sounds like you're on the right path.

Rather than using a breadboard, I hand-wired up a test board with a socket for the ESP-01, a local 3.3 regulator and filter capacitors, pullup and pulldown resistors where required, pushbuttons for reset and GPIO0 program, and connector pins for 5v power and the serial interface. Nothing fancy, but it has saved me from all the pitfalls of a flaky or incorrect breadboard setup. I've been using it with ESP-01s for almost 7 months... all my flashes work, and i haven't bricked anything yet.