ESP8266 Community Forum

Hey people!

Working at my Bachelor Thesis I designed a small board containing two sensors and an ESP8266.
The design is based on the Olimex MOD-WIFI and was extended by the sensors. Moreover I replaced the flash chip by this one: W25Q16DVIG.

I also added a timer that triggers a reset if a button is pushed that pulls GPIO0 to GND.
By pressing the button the ESP can be put into bootloader mode.

When I connect the board and press the button, I am able to use the esptool.py to read the mac address and the flash id. Also flashing a program using the Arduino IDE is possible. Which proves that the bootloader mode can be entered.
However when I start the serial monitor (in normal mode) I just get random characters that repeat somehow.
I already tried different baud rates and tested the board for short circuits but was not able to fix it.

Can anybody help me out?

Are you sure you are gettiing out of bootloader mode.....try repowering device

minils wrote:Hey people!

Working at my Bachelor Thesis I designed a small board containing two sensors and an ESP8266.
The design is based on the Olimex MOD-WIFI and was extended by the sensors. Moreover I replaced the flash chip by this one: W25Q16DVIG.

I also added a timer that triggers a reset if a button is pushed that pulls GPIO0 to GND.
By pressing the button the ESP can be put into bootloader mode.

When I connect the board and press the button, I am able to use the esptool.py to read the mac address and the flash id. Also flashing a program using the Arduino IDE is possible. Which proves that the bootloader mode can be entered.
However when I start the serial monitor (in normal mode) I just get random characters that repeat somehow.
I already tried different baud rates and tested the board for short circuits but was not able to fix it.

Can anybody help me out?

Hi, sounds like you don't have GPIO 2 high in the cases that you have a problem.

Normal boot: GPIO 0 HIGH, GPIO 2 HIGH.
Flash boot: GPIO 0 LOW, GPIO 2 - subject to much debate - for most people doesn't seem to matter - prefered HIGH.
SD card boot: GPIO 0 HIGH, GPIO 2 LOW.

In SD card boot the serial will display the communication between the ESP and the SD card - which you don't have - so it's just a 'hello where are you' from the ESP that it keeps sending in an ever more sorry tone as time goes on, but it never gives up hope, serial can't detect tone so you don't see it.
So please, ensure GPIO 2 is HIGH at boot or reset and don't distress the poor thing.
Hope that helps.

xtal wrote:Are you sure you are gettiing out of bootloader mode.....try repowering device

I'm pretty sure. I also tried which should put the device from bootloader mode to flash mode.

Barnabybear wrote:Hi, sounds like you don't have GPIO 2 high in the cases that you have a problem.

Normal boot: GPIO 0 HIGH, GPIO 2 HIGH.
Flash boot: GPIO 0 LOW, GPIO 2 - subject to much debate - for most people doesn't seem to matter - prefered HIGH.
SD card boot: GPIO 0 HIGH, GPIO 2 LOW.

In SD card boot the serial will display the communication between the ESP and the SD card - which you don't have - so it's just a 'hello where are you' from the ESP that it keeps sending in an ever more sorry tone as time goes on, but it never gives up hope, serial can't detect tone so you don't see it.
So please, ensure GPIO 2 is HIGH at boot or reset and don't distress the poor thing.
Hope that helps.

I use GPIO2 as SDA to communicate with a magnetometer via I2C.
Therefore I placed a 12K pull-up on GPIO2.

I just double checked it with my multimeter and the pin is definitely HIGH.