I'm trying to wire up the SIM800L module to my arduino nano using this post as a referencehttps://forum.arduino.cc/index.php?topic=496064.0
Currently here is how I have everything wired up:
The way I understand it, the SIM800L needs between 3.7v and 4.2v @ 2amps to function, which I have. The 2 wires that come from the arduino, in this case D8 (RX) and D9 (TX) need to be converted down into 2.8v using a logic level shifter / converter (I'm not sure if I have this wired up correctly though). Based on my digram, on the LV end of the logic level shifter I get 2.8v from TX and 1.1v (roughly) from the RX.
dannable:
Shouldn't you have 5v into HV and 2.8v into LV?
I was trying to figure out why you had a wire going from the 4.9v supply to your home made level shifter... I think my understanding of how a level shifter works is wrong. I thought that you put in high voltage into the HV pin along with the rx and tx wires again on the high side and the level shifter downs the voltage to 2.8 as well as corrects the signal, i didn’t think you had to also supply power into the LV pin.
Good question, I found my self asking the same thing, hence why I put the 2.8v into the HV pin, thinking, wrongly, it would set the voltage.
Had a look over the PDF, looking at the digram I think I need to have 5v going into the HV and 2.8v from the buck converter going into the LV pin (this lets the shifter know what voltage we are shifting too?), then at the high end have the RX and TX from the arduino and at the low end the RX and TX going into the SIM800L.
