SIM 800C interfacing


This is my first circuit following the Datasheet of SIM800C. I’ve tried to design a simple interfacing between atmega 328 and SIM800C. But I’m bit skeptical about the design as this is my first design. Can some one please go through the schematic and let me know if I’m doing something wrong…

Thank u very much!!



The schematic is looking blur, is it bad network or image itself is lower resolution, can you check and upload a higher resolution?


Ok… Please take a look at this attached image.
Is it clear now ?


You have to use level translator chip and use VDD_EXT for translation. You can use TXS0104 chip for it and connecting DTR pin to MCU through level translator will help in controlling sleep modes.


Thank you Ravi. I realised it lately and following the documentation I’ve come up with the circuit shown below. Please take a look


I havent tried the transistor based level translation. I would recommend TXS0102 or TXS0104 for level translation. They work flawlessly.