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mc55i with dual external sim cards

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SpeedyX

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Hi all,

I want to connect 2 sim cards to MC55i GPRS module for single using, but the module has support for only one sim card.
Maybe it can be done by using 6 channel multiplexer or analog switch or something like that.

I will shutdown the module's power and then will select one of two sim cards and will restart the module. The module will work only with one sim card.

How can I do this?
Should I multiplex all 6 pins of sim card?
Which IC can be used for switching/multiplexing?
 

SIM cards are actually using 5 pins, VPP is unconnected. GND don't need to be multiplexed, so there is a maximum of 4 pins that would be switched. IO is the only bidirectional pin, if MC55i has no problems with some additional load, multiplexing IO can be enough. Standard 74HC405x analog multiplexers should work well.
 

Thanks for the answer FvM.

I've added the external sim holder connection schematic from the datasheet. Here, the CCGND is common and do not needed to be multiplexed, but all the other pins (CCVCC, CCCLK, CCIO, CCRST and CCIN) must be multiplexed?

VPP is unconnected
Click to expand...
Here the VCC pin is connected.

if MC55i has no problems with some additional load...
Click to expand...
How can I check this?

It would be so simple to multiplex only the CCIO pins of 2 sim cards, but how can I be sure that it will be enough?

Best regards
 

Also I'm looking for MC55i library for Eagle
 

You have been talking of the 6 SIM card pins. CCIN isn't a card contact. It's the detect switch, you don't need to multiplex it.
Here the VCC pin is connected.
Click to expand...
Surely. I didn't tell different.
how can I be sure that it will be enough
Click to expand...
You should try.
 

FvM said:
Here the VCC pin is connected.
Click to expand...
Surely. I didn't tell different.
Click to expand...
Yes, you are right, I also looked that.
There is a VPP pin except VCC. And the VPP is unconnected, VCC is connected.
I was thinking that VCC and VPP are the same pin.

Actually I'm looking for a person who has experience exactly with this subject.

If I don't multiplex the CCIN (card detect pin), how the module will understand that there is a sim card?

Thanks
 

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