added hint on `hf 14a apdu`. close #495

diff --git a/client/cmdhf14a.c b/client/cmdhf14a.c
index a0f3ce57e50fe712da0849e94c47a84f389d129d..8064724cc3185a66b2e86f0c38c4bb8baaf9646c 100644 (file)
--- a/client/cmdhf14a.c
+++ b/client/cmdhf14a.c
@@ -725,6 +725,7 @@ int ExchangeAPDU14a(uint8_t *datain, int datainlen, bool activateField, bool lea
        return 0;
 }
 
+// ISO14443-4. 7. Half-duplex block transmission protocol
 int CmdHF14AAPDU(const char *cmd) {
        uint8_t data[USB_CMD_DATA_SIZE];
        int datalen = 0;
@@ -734,6 +735,7 @@ int CmdHF14AAPDU(const char *cmd) {
        
        if (strlen(cmd) < 2) {
                PrintAndLog("Usage: hf 14a apdu [-s] [-k] [-t] <APDU (hex)>");
+               PrintAndLog("Command sends an ISO 7816-4 APDU via ISO 14443-4 block transmission protocol (T=CL)");
                PrintAndLog("       -s    activate field and select card");
                PrintAndLog("       -k    leave the signal field ON after receive response");
                PrintAndLog("       -t    executes TLV decoder if it possible. TODO!!!!");
@@ -1019,7 +1021,7 @@ static command_t CommandTable[] =
   {"cuids",  CmdHF14ACUIDs,        0, "<n> Collect n>0 ISO14443 Type A UIDs in one go"},
   {"sim",    CmdHF14ASim,          0, "<UID> -- Simulate ISO 14443a tag"},
   {"snoop",  CmdHF14ASnoop,        0, "Eavesdrop ISO 14443 Type A"},
-  {"apdu",   CmdHF14AAPDU,         0, "Send ISO 14443-4 APDU to tag"},
+  {"apdu",   CmdHF14AAPDU,         0, "Send an ISO 7816-4 APDU via ISO 14443-4 block transmission protocol"},
   {"raw",    CmdHF14ACmdRaw,       0, "Send raw hex data to tag"},
   {NULL, NULL, 0, NULL}
 };