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sim900d based design . The Module powers up, but shows that no sim is inserted ,

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sherazi

sherazi

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hi have searched the forum but didnt get the answer and dint want to hijack any thread...so started a new one

i am woking on sim900d based design . The Module powers up, but shows that no sim is inserted , i have inserted a sim , whenever i power it up i get this on serial port

Code: 
RDY

+CPIN: NOT INSERTED

+CFUN: 1

+CREG: 2

+CREG: 0

i have checked the voltage on simvdd and i found that for a few miliseconds the multimeter shows some voltage that then drops to approx zero ..

i have even replaced the module and also tried to connect another sim holder circuit from a dev board but still got no results ... any solutions?? plz do help
 

check the sim holder ... i think not properly inserted....if the sim is working check the supply source for sim ....... see 1.8v and 3 v sim card only works in sim900.. check the supply to sim from 900 module... check that supply pin to sim900 is not insulated.... check the gap between the holder and sim interface...
 

Check whether a capacitor of 0.1uF is connected between SIM_VDD pin and GND...
 

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