breadcrumb3000

number format should be +[country code][area code][mobile number] like +8651345552121

See the demo: https://github.com/Ai-Thinker-Open/GPRS_C_SDK/blob/master/demo/i2c/src/demo_i2c.c

are you using Powershell?

Update time by NTP server.

It looks like one of my A9G units just had an issue with the TF card reader. MP3 playback from the TF card worked on another A9G unit.

Thank you @zkemble . It looks like the procedure to copy file from SD card to internal flash is: 1. API_FS_OPEN and API_FS_READ the file on SD card based on...

Try using this: https://lcsc.com/product-detail/DC-DC-Converters_XL2013E1_C73339.html

Are you connected to the correct pins?

have you tried building your app using "./build.bat demo $PROJ release" to build in "release" mode instead of "debug" mode? Source is here : https://www.iot-experiments.com/ai-thinker-a9-module-with-custom-firmware/

Watchdog?