- fixed iso1443a ManchesterDecoder in order to fix broken Snoop/Sniff

[proxmark3-svn] / armsrc / util.c

diff --git a/armsrc/util.c b/armsrc/util.c
index dc18e5e385247ac727a259c6095bd8e008c0b60f..6d34ae5e80f0f3cad520bdf480f75e9396956638 100644 (file)
--- a/armsrc/util.c
+++ b/armsrc/util.c
@@ -316,9 +316,9 @@ uint32_t RAMFUNC GetDeltaCountUS(){
 
 
 //  -------------------------------------------------------------------------
-//  Mifare timer. Uses ssp_clk from FPGA 
+//  Timer for iso14443 commands. Uses ssp_clk from FPGA 
 //  -------------------------------------------------------------------------
-void StartCountMifare()
+void StartCountSspClk()
 {
        AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0) | (1 << AT91C_ID_TC1) | (1 << AT91C_ID_TC2);  // Enable Clock to all timers
        AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC0XC0S_TIOA1               // XC0 Clock = TIOA1
@@ -330,7 +330,7 @@ void StartCountMifare()
        AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK // TC1 Clock = MCK(48MHz)/2 = 24MHz
                                                        | AT91C_TC_CPCSTOP                              // Stop clock on RC compare
                                                        | AT91C_TC_EEVTEDG_RISING               // Trigger on rising edge of Event
-                                                       | AT91C_TC_EEVT_TIOB                    // Event-Source: TIOB1 (= ssc_clk from FPGA = 13,56MHz / 16)
+                                                       | AT91C_TC_EEVT_TIOB                    // Event-Source: TIOB1 (= ssp_clk from FPGA = 13,56MHz/16)
                                                        | AT91C_TC_ENETRG                               // Enable external trigger event
                                                        | AT91C_TC_WAVESEL_UP                   // Upmode without automatic trigger on RC compare
                                                        | AT91C_TC_WAVE                                 // Waveform Mode
@@ -339,7 +339,7 @@ void StartCountMifare()
        AT91C_BASE_TC1->TC_RC = 0x04;                                                   // RC Compare value = 0x04
 
        // use TC0 to count TIOA1 pulses
-       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;                               // disable TC0  
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;                               // disable TC0
        AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_XC0                              // TC0 clock = XC0 clock = TIOA1
                                                        | AT91C_TC_WAVE                                 // Waveform Mode
                                                        | AT91C_TC_WAVESEL_UP                   // just count
@@ -354,29 +354,40 @@ void StartCountMifare()
                                                        | AT91C_TC_WAVE                                 // Waveform Mode
                                                        | AT91C_TC_WAVESEL_UP;                  // just count
        
-       
        AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN;                                // enable TC0
        AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN;                                // enable TC1
        AT91C_BASE_TC2->TC_CCR = AT91C_TC_CLKEN;                                // enable TC2
 
-       // activate the ISO14443 part of the FPGA. We need the clock and frame signals.
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_LISTEN);
-
-       // synchronize the counter with the ssp_frame signal.
+       //
+       // synchronize the counter with the ssp_frame signal. Note: FPGA must be in any iso14446 mode, otherwise the frame signal would not be present 
+       //
+       while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME));   // wait for ssp_frame to go high (start of frame)
        while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME);              // wait for ssp_frame to be low
-       while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME));   // sync on rising edge of ssp_frame (= start of transfer)
-
+       // after the falling edge of ssp_frame, there is delay of 1/13,56MHz (73ns) until the next rising edge of ssp_clk. This are only a few
+       // processor cycles. We therefore may or may not be able to sync on this edge. Therefore better make sure that we miss it:
+       while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK));     // wait for ssp_clk to go high
+       // note: up to now two ssp_clk rising edges have passed since the rising edge of ssp_frame
+       // it is now safe to assert a sync signal. This sets all timers to 0 on next active clock edge
        AT91C_BASE_TCB->TCB_BCR = 1;                                                    // assert Sync (set all timers to 0 on next active clock edge)
+       // at the next (3rd) ssp_clk rising edge, TC1 will be reset (and not generate a clock signal to TC0)
+       // at the next (4th) ssp_clk rising edge, TC0 (the low word of our counter) will be reset. From now on,
+       // whenever the last three bits of our counter go 0, we can be sure to be in the middle of a frame transfer.
+       // (just started with the transfer of the 4th Bit).
+       // The high word of the counter (TC2) will not reset until the low word (TC0) overflows. Therefore need to wait quite some time before
+       // we can use the counter.
+       while (AT91C_BASE_TC0->TC_CV < 0xFFF0);
 }
 
 
-uint32_t RAMFUNC GetCountMifare(){
+uint32_t RAMFUNC GetCountSspClk(){
        uint32_t tmp_count;
        tmp_count = (AT91C_BASE_TC2->TC_CV << 16) | AT91C_BASE_TC0->TC_CV;
-       if ((tmp_count & 0xffff) == 0) { //small chance that we may have missed an increment in TC2
+       if ((tmp_count & 0x0000ffff) == 0) { //small chance that we may have missed an increment in TC2
                return (AT91C_BASE_TC2->TC_CV << 16);
        } 
        else {
                return tmp_count;
        }
 }
+
+