MicroPython Forum (Archive)

Hello,

I have a project that works just fine, is connected to the Internet and all, but now I'd need to change the program running on the device.

When I try to connect to it on PuTTY, I see this:

ets Jun 8 2016 00:22:57

rst:0x1 (POWERON_RESET),boot:0x2 (DOWNLOAD_BOOT(UART0/UART1/SDIO_REI_FEO_V2))
waiting for download

I suppose this is because it has already started to run the application on the ESP32. I can reflash it using esptool, but even after that I get the same message.

Is there a way to power up the device and not run the boot.py and correspondingly the main app?

Many thanks!

-h.

What you see is the built-in bootloader of the ESP32 chip, which starts when at Power-up or reset GPIO0 is connected to GND or at low level. So please check the GPIO0 connection. This is nothing which can be changed by the MicroPython firmware.

Ah - how wrong a n00bie can be. Many thanks for clarifying this to me.

As it happens, I don't have anything riding on GPI0 but I have a LCD, a buzzer and HCSR04 ultrasound sensor attached.

So, as I understand it, I should connect the GPI0 to the 3.3V if I want access to the board now?

The ESP32 has an internal pull-up for GPIO0. That ensures proper operation if it is left floating. So I guess you have something connected to GPIO0 which pulls it low. Please check your wiring.

Depending on the board it might be control line setting of PuTTY. Set PuTTY to Flow control = None.
It is under Confguration->Connection->Serial->Flow Control

Thanks again! This board is very speedy and informative.

Hello Robert,

I double-checked and yes indeed, I have the ultrasound sensor's echo pin as GPI0. I guess moving it to some other pin will help me with this.

Thank you very much for the reply, I would have lost my remaining hair trying to figure this out by myself.

Heikki

heikki.hietala wrote: ↑

Sat Oct 13, 2018 9:20 am

I double-checked and yes indeed, I have the ultrasound sensor's echo pin as GPI0. I guess moving it to some other pin will help me with this.

I had similar situation (servo signal line connected to GPIO0) and did a different solution. Instead of moving to a different pin I soldered a small button between GPIO0 and VCC. That way I can press the button during powering the ESP and then release it:
https://www.esp8266.com/viewtopic.php?f ... 515#p78398

Thanks Hermann, it occurred to me too. This device will be located a little far from me and won't be reprogrammed, so I will just change pins, but keep that in mind for future devices.