Hi,
I tried to use the internal RTC of ESP32 to save at fixed intervals data from a SHT31 sensor on a SD card and to display on an LED 1306SSD because whereI’m going to put the ESP32 I have no WiFi so that I cannot use the NTP server. During the inervals the ESP32 is in deepsleep.
This seems to work but all the Serial.print commands I’ve put in the setup and i a callback function are not displayed on the serial monitor.
When the ESP32 awakes I just read on the monitor the following message
rst:0x5 (DEEPSLEEP_RESET), boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip; 0, SPIWP:0xee
clk_drv:ox00, q_drv:0x00, d_drv:0x00, cs0:drv:0x00, hd_drv:0.×00, wp_drv.0x00
mode:DIO, clock div:1
load:0x3fff0030, len:1344
load:0x40078000, len:13924
ho 0 tail 12 room 4
load:0x40080400, len:3600
entry 0x400400805f0
and then a couple of garbage characters ( a question point in a black square and a white square)
I’ve tried to insert delays of different amount after the Serial.begin(115200) and I’ve tried different baud rates but nothing seems to work.
I don’t understand what’s going on.
I’d be very grateful if you could help me
Thanks 
Bruno