BS 2P(40) intyerface with sim card reader

04A236

HELP!!!!!~· We were thinking of using basic stamp 2p to interface with a serial sim card reader... But u think it's possible? We really need help.... Urgent.... Or are there any ways for the basic stamp to read from the sim card?

Jon Williams

Can you offer more specifics? How about a link to the device you want your BS2p to connect to? What about tech docs?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax
Dallas Office

04A236

Hi Jon,
The User Manual is quite limited...·
I've scaned a copy of it (as attached)...·
There's no specific technical description given...


This is the link on the SIM Card Reader : http://www.comodow.com/en/enpd882u.htm

Thank you,
Rita

Dave Paton

From what the page says, it's a USB SIMcard reader, which means you'll need to build an interface to convert the USB signals to serial. I'd recommend the very nice chips from FDDI, available (very conveniently) from Parallax. After that you'll need to figure out the protocol that the device normally uses to talk to the PC resident program it ships with.

It might be easier for you to talk to the SIMcard directly instead of trying to do the SIM ->USB -> serial route. 15 seconds with Google showed me that Philips makes a one-chip solution for turning SIM to I^2C. The product page is here:

http://www.semiconductors.philips.com/pip/TDA8003.html

It looks like the TDA8003 will also allow you to speak a (slightly) simplified version of the SIMcard protocol. It will require getting a little down and dirty, but I think it'll be a lot easier to write for a published specification (GSM11.12 IIRC) than trying to reverse engineer a proprietary protocol (as used in your USB-SIM device).

My $0.02.

-dave

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
This is not a sig. This is a duck. Quack.

black_tag10

SO how are the TDA8003 going to work???... does it mean that, not every SIM card reader is a I^2C Device???
and the most important thing is...
how is it gonna "communicate" with BS2P???????????????????????????, through the command I2COUT & I2CIN???

Best Regards

Dave Paton

The whole purpose of the TDA8003 is to convert an I2C bitstream into the wonky timing protocol that SIMcards use. You'll need to send the right commands and look for the right responses, but you'll be able to use the Stamp's I2C routines (I2Cin, I2Cout) instead of trying to reverse engineer the USB protocol for the dongle you have. SIMcards do NOT speak I2C normally. Think of the TDA8003 as an interpreter. If you Google for SIM card protocol you'll find lots of documents that describe the standard and the communication protocol that the SIM cards use. The part you're interested is the message protocol, not the timing diagrams, since adapting to the timing requirements is what the TDA8003 is for.

And no, SIM cards in their natural habitat (cell phones) are not usually addressed as I2C devices. They're interfaced directly to one of the microcontrollers in the phone. Chips like this one make it handy to interface them with limited pincount devices, like the Stamp, and for people who don't want to deal with the protocol, like you

-dave

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
This is not a sig. This is a duck. Quack.