Serial Comunication Configuration 9600 baud

[JpEncausse]

Hello, I'm running example code like deepsleep or wifi. It works but the Serial is all scramble (not UTF-8 ?)

At first I didn't get any readable caracter, I swtich to Serial.begin(9600); it's better but still issue :

)�΀␄z�␔)L␌H�␎�Boot number: 1
Wakeup was not caused by deep sleep: 0
Setup ESP32 to sleep for every 10 Seconds
Going to sleep now
�'�����␜W␌.���C�c�Boot number: 2
Wakeup caused by timer
Setup ESP32 to sleep for every 10 Seconds
Going to sleep now

Here is my configuration

[platformio]
src_dir = example/deepsleep

[env:ttgo-t-oi-plus]
platform = espressif32
board = ttgo-t-oi-plus
framework = arduino

build_flags = 
    -DCORE_DEBUG_LEVEL=1

What am I missing to get correct debug information ?

[TMillesich]

Every time an ESP32 is starting up, it is sending boot messages with 115200 baud. That's the scrambled part before the "Boot number:" here.

The boot messages printed by the ROM bootloader can be suppressed by connecting GPIO15 to GND using a resistor during boot and then still use it as an output pin after boot.

Source: https://www.esp32.com/viewtopic.php?t=1658