8.3.3 User Card Interface Module

User card interface module can also operate per the EMV4.3 and ISO7816-3 standard and support asynchronous operating mode. In addition, the user card interface module also supports synchronous type 1 operating mode and synchronous type 2 operating mode, per ISO7816-10. Like the SAM card interface modules, the user card interface module also has IO, CLK, and RST pins. The user card interface module also has a PRES pin that is used for detection of user card insertion or removal.

C4 and C8 are two pins that are only present on the user card interface. These are open drain bi-directional IOs that are controlled by the bit [5] and bit [4] of user card synchronous mode settings register (Reg 0x09) when the card interface is activated. These bits act as both control and status bits for the C4 and C8 signals. If a ‘0’ is written to either of these bits the corresponding pin is driven low by the TCA5013. However, when a ‘1’ is written to the register bit, the corresponding pin is pulled up by an internal pull-up resistor. In this state an external device can drive the pin low. If the pin is driven low, then the corresponding bit in the register changes to reflect the status of the pin.