6-pin Sim Holder


Has anyone tried using a 6-pin sim holder with a Q26xx model? I am trying to debug my hardware problem and the Wavecom Customer Design Guideline for this is somewhat lacking. It obviosly works fine with the dev board, but not on our board. We have pin 1 & pin 5 connected to SIM_VCC, pin 2 connected to SIM_RST, pin 3 connected to SIM_CLK, pin 4 connected to GND, and pin 6 connected to SIM_IO. I did a continuity check and everything is fine.

Any suggestions or input as to what else I can try?



Apparently you have to tie SIMPRES to 1.8V if you want to use a 6-pin sim holder, regardless if you want to use that feature or not. I don’t see the point in multiplexing that GPIO though.