anshumantech
Newbie level 3
I am working on GSM SIM900 module the previous version of PCB for GSM works and IC generate 3.3V at SIM VDD pin, but in the new version of PCB GSM IC doesn't generate 3.3V for the SIM card (at pin SIM VDD). And the AT commands doesn't work on new PCB. What could be reason for this?