Hello everyone,
I am trying to use SIM908 with Arduino, but having problems with it. I used the reference design to create my own, below you will find the schematic. I have a stable 3.6~volt VBAT.
The problem is : the netlight pin is always high, therefore the net status LED is always shining. It should be blinking, but it doesn't. When i press the power button the LED goes off, as soon as i stop pressing it goes on again.
The PWRKEY pin should be internally pulled high as i know (to 3v?) but it is 1.3V, and when the button is pressed it is grounded as it should be.
I am tracing my routes on the PCB but haven't been able to find any short circuits or jumps. What may be the problem? Any help is appreciated. Thank you.
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Also, I have tried connecting a 3.7V li-ion battery directly to the pins, still the same thing (weaker light tho)
One more thing i noticed : the SIM908 chip gets unusually hot, not so much but i don't think it is supposed to be like that.