add 'detectreader' command - listen for external reader fields

armsrc/appmain.c

@@ -7,6 +7,7 @@
 
 
 #include <proxmark3.h>
+#include <stdlib.h>
 #include "apps.h"
 #ifdef WITH_LCD
 #include "fonts.h"
@@ -727,6 +728,10 @@ void UsbPacketReceived(BYTE *packet, int len)
 			MeasureAntennaTuning();
 			break;
 
+		case CMD_LISTEN_READER_FIELD:
+			ListenReaderField(c->ext1);
+			break;
+
 		case CMD_HID_DEMOD_FSK:
 			CmdHIDdemodFSK();				// Demodulate HID tag
 			break;
@@ -904,3 +909,85 @@ void SpinDelay(int ms)
 		WDT_HIT();
 	}
 }
+
+// listen for external reader 
+void ListenReaderField(int limit)
+{
+	int lf_av, lf_av_new, lf_baseline= -1, lf_count= 0;
+	int hf_av, hf_av_new,  hf_baseline= -1, hf_count= 0;
+
+#define LF_ONLY		1
+#define HF_ONLY		2
+
+	LED_A_OFF();
+	LED_B_OFF();
+	LED_C_OFF();
+	LED_D_OFF();
+
+	lf_av= ReadAdc(ADC_CHAN_LF);
+
+	if(limit != HF_ONLY && lf_baseline ==  -1) 
+		{
+		DbpString("LF 125/134 Baseline:");
+		DbpIntegers(lf_av,0,0);
+		lf_baseline= lf_av;
+		}
+
+	hf_av= ReadAdc(ADC_CHAN_HF);
+
+
+	if (limit != LF_ONLY && hf_baseline == -1) 
+		{
+		DbpString("HF 13.56 Baseline:");
+		DbpIntegers(hf_av,0,0);
+		hf_baseline= hf_av;
+		}
+
+	for(;;) 
+		{
+		if(BUTTON_PRESS()) 
+			{
+			LED_B_OFF();
+			LED_D_OFF();
+			return;
+			}
+		WDT_HIT();
+
+
+		if (limit != HF_ONLY) 
+			{
+			if (abs(lf_av - lf_baseline) > 10)
+				LED_D_ON();
+			else
+				LED_D_OFF();
+			++lf_count;
+			lf_av_new= ReadAdc(ADC_CHAN_LF);
+			// see if there's a significant change
+			if(abs(lf_av - lf_av_new) > 10) 
+				{
+				DbpString("LF 125/134 Field Change:");
+				DbpIntegers(lf_av,lf_av_new,lf_count);
+				lf_av= lf_av_new;
+				lf_count= 0;
+				}
+			}
+
+		if (limit != LF_ONLY) 
+			{
+			if (abs(hf_av - hf_baseline) > 10)
+				LED_B_ON();
+			else
+				LED_B_OFF();
+			++hf_count;
+			hf_av_new= ReadAdc(ADC_CHAN_HF);
+			// see if there's a significant change
+			if(abs(hf_av - hf_av_new) > 10) 
+				{
+				DbpString("HF 13.56 Field Change:");
+				DbpIntegers(hf_av,hf_av_new,hf_count);
+				hf_av= hf_av_new;
+				hf_count= 0;
+				}
+			}
+		}
+}

armsrc/apps.h

@@ -15,6 +15,7 @@ void SpinDelay(int ms);
 void SpinDelayUs(int us);
 void ToSendStuffBit(int b);
 void ToSendReset(void);
+void ListenReaderField(int limit);
 void AcquireRawAdcSamples125k(BOOL at134khz);
 void DoAcquisition125k(BOOL at134khz);
 extern int ToSendMax;

include/usb_cmd.h

@@ -69,6 +69,7 @@ typedef struct {
 // For measurements of the antenna tuning
 #define CMD_MEASURE_ANTENNA_TUNING					0x0400
 #define CMD_MEASURED_ANTENNA_TUNING					0x0401
+#define CMD_LISTEN_READER_FIELD						0x0402
 
 // For direct FPGA control
 #define CMD_FPGA_MAJOR_MODE_OFF						0x0500	// ## FPGA Control

winsrc/command.cpp

@@ -677,6 +677,22 @@ static void CmdLoread(char *str)
 	SendCommand(&c, FALSE);
 }
 
+static void CmdDetectReader(char *str)
+{
+	UsbCommand c;
+	// 'l' means LF - 125/134 kHz
+	if(*str == 'l') {
+		c.ext1 = 1;
+	} else if (*str == 'h') {
+		c.ext1 = 2;
+	} else if (*str != '\0') {
+		PrintToScrollback("use 'detectreader' or 'detectreader l' or 'detectreader h'");
+		return;
+	}
+	c.cmd = CMD_LISTEN_READER_FIELD;
+	 SendCommand(&c, FALSE);
+}
+
 /* send a command before reading */
 static void CmdLoCommandRead(char *str)
 {
@@ -2573,6 +2589,7 @@ static struct {
 	"buffclear",		CmdBuffClear,0,		"    Clear sample buffer and graph window",
 	"dec",				CmdDec,1,		"    Decimate samples",
 	"detectclock",		Cmddetectclockrate,1, "    Detect clock rate",
+	"detectreader",		CmdDetectReader,0, "['l'|'h'] -- Detect external reader field (option 'l' or 'h' to limit to LF or HF)",
 	"em410xsim",		CmdEM410xsim,1,		"<UID> -- Simulate EM410x tag",
 	"em410xread",		CmdEM410xread,1,	"[clock rate] -- Extract ID from EM410x tag",
 	"em410xwatch",		CmdEM410xwatch,0,	"    Watches for EM410x tags",