I have uC which runs on 3,3V but could also handle 3,6V.
Sim900 runs from 3,6-4,5V. When transmitting voltage drops for about 0,4V, so sim900 should have at least 4,0V.
Connection between uC and sim900 is serial and what I need is voltage level translator 3,3V <=> 4V.
Thank you !
Best regards !