SIM Power Supply
VSIM is the power supply to the SIM card.
During the activation/deactivation process, VSIM output is automatically controlled.
The on/off of VSIM can also be controlled by directly programming the SIM_CTL0(Power_On bit[7]).
Protocol Mode
In normal case, the sim card is in PROT_MODE 0.
---ACK/NACK(PROT_MODE 1)
In this case, the process flow of simcard control as:
1. send command to sim card
2. receive ACK/NACK from sim card(not must)
3. send data to sim card(not must)
4. receive ACK/NACK from sim card(not must)
5. receive data from sim card
Note: the item 2/3/4 are not must all, but it must has one of them, and it must need one ACK/NACK.
The commands satisfy the rule are: select, verify, change, seek, enable, disable, increase, unlock, terminal response.
@@ ACK only when send data
@@ NACK only when send data
@@ ACK/NACK when send data
@@ ACK when receive data
In this case, there are no data need to send but just command. The received data should followed the ACK signal.
The commands satisfy the rules are: status, read binary, read record, get response and fetch.
@@ No ACK/NACK (PROT_MODE 2)
In this case, there are no data need to send but just command.
The received data has no ACK signal but just some NULL signals
The commands satisfy the rules are as : invalidte, rehabilitate
@@ Protocol State Machine
原文：http://www.cnblogs.com/dongyanxia1000/p/5057031.html