Welcome to FreeCalypso SIMsniff
===============================

FreeCalypso SIMsniff is an alternative project to Osmocom SIMtrace, created in
response to technical limitations of the latter.  Both tools seek to solve the
same problem (trace or sniff all communication between a phone, modem or other
interface device and a SIM card) and use some passive hardware components in
common (the FPC adapter cable that goes into the phone's SIM socket), but use
different active components: Osmocom SIMtrace uses an AT91SAMx MCU as the ISO
7816-3 sniffing receiver, whereas FC SIMsniff uses a voltage translating buffer
followed by an iCE40 FPGA instead.

The principal practical difference between the two tools is that FC SIMsniff is
electrically clean and proper:

* The sniffing apparatus makes a strictly Hi-Z connection to the SIM bus being
  sniffed;

* The SIM bus itself is solidly connected from the phone's SIM socket to the
  physical SIM without any switches or pull-ups or other Heisenbug-inducing
  artifacts;

* The sniffing apparatus supports all 3 voltage classes that can be put out by
  the ME or other interface device: 1.8V, 3V and 5V are all good.

The hardware setup of FC SIMsniff consists of:

* The same SIMtrace FPC cables (going from a SIM socket to the 6-pin FPC
  connector) that were originally developed for SIMtrace1/2 and are sold by
  Sysmocom;

* An off-the-shelf Lattice Icestick FPGA board;

* A little bit of custom hardware: two very simple boards in the initial
  version, intending to consolidate them into one board in the final version,
  see doc/Sniffing-hw-setup for the details.

This source repository contains:

boards		Design files for little adapter boards
fpga		Gateware for the iCE40HX1K FPGA on the Icestick board
sw		Host software tools