this board can be connected to an expansion connector of the WT32-SC01 from Wireless-Tag (c) http://www.wireless-tag.com/portfolio/wt32-sc01/

Features supported by the PCB:
LiPo - LiIon battery charger
2 push buttons
Power Swich
DS3121M + backup battery RTC clock
DS1307 RTC + Crystal capability
Micro SD connector
MCP4725 DAC + Speaker amplifier
I2C, IO, Control, Power connectors
Battery Voltage Sensor
Micro USB connector for charging
Power LED
RF connector
The PCB dimensions and holes fit to the WT32-SC01's.

Demo Source Code
The demo source code tests all the board's feature. The testing code is provided "as is" and it includes :

DAC setup and test
Basic GUI
I2C scanner
JPEG display
SD Card files access
SPIFF files access
RTC management
Web Server
LVGL graphical interface

The PCB is proposed with different options (alone, soldered, kit ...)