SniffISO15693: Add functions to codec to enable autocalibration

Signed-off-by: cacke-r <[email protected]>

Author: cacke-r

Firmware/Chameleon-Mini/Codec/SniffISO15693.c

@@ -52,6 +52,7 @@ static volatile uint8_t ReaderByteCount;
 static volatile uint8_t CardByteCount;
 static volatile uint16_t SampleDataCount;
 static volatile uint8_t bBrokenFrame;
+static bool bAutoThreshold = true;
 
 /////////////////////////////////////////////////
 // VCD->VICC
@@ -272,6 +273,20 @@ INLINE void SNIFF_ISO15693_READER_EOC_VCD(void) {
 // VICC->VCD
 /////////////////////////////////////////////////
 
+
+/* Inline function to set the threshold, if bAutoThreshold is enabled*/
+INLINE void SetDacCh0Data(uint16_t ch0data){
+    /* TODO: Check if either of the branches can be avoided */
+    /* to optimize the performance */
+    if(bAutoThreshold){
+        if (ch0data < 0xFFF)
+            DACB.CH0DATA = ch0data;
+        else
+            DACB.CH0DATA = 0xFFF;
+    }
+    return;
+}
+
 /* Initialize card sniffing options
 Note: Currently implemented only single subcarrier SOC detection
  */
@@ -394,8 +409,8 @@ INLINE void CardSniffInit(void) {
     ADCA.EVCTRL = ADC_SWEEP_01_gc;
 
     /* Write threshold to the DAC channel 0 (connected to Analog Comparator positive input) */
-    DACB.CH0DATA = DemodFloorNoiseLevel + (DemodFloorNoiseLevel >> 3); /* Slightly increase DAC output to ease triggering */
-    DACB.CH0DATA |= -( (DACB.CH0DATA & 0xFFF) < DemodFloorNoiseLevel); /* Branchfree saturating addition */
+    SetDacCh0Data(DemodFloorNoiseLevel + (DemodFloorNoiseLevel >> 3)); /* Slightly increase DAC output to ease triggering */
+
 
     /**
      * Finally, now that we have the DAC set up, configure analog comparator A (the only one in this MCU)
@@ -449,8 +464,8 @@ ISR_SHARED isr_SNIFF_ISO15693_ACA_AC0_VECT(void) {
 
     ACA.AC0CTRL = AC_ENABLE_bm | AC_HSMODE_bm | AC_HYSMODE_LARGE_gc | AC_INTMODE_RISING_gc | AC_INTLVL_OFF_gc; /* Disable this interrupt */
 
-    DACB.CH0DATA = DemodFloorNoiseLevel + (DemodFloorNoiseLevel >> 2); /* Blindly increase threshold after 1 pulse */
-    DACB.CH0DATA |= -( (DACB.CH0DATA & 0xFFF) < DemodFloorNoiseLevel); /* Branchfree saturating addition */
+    SetDacCh0Data(DemodFloorNoiseLevel + (DemodFloorNoiseLevel >> 2)); /* Blindly increase threshold after 1 pulse */
+
     /* Note: by the time the DAC has changed its output, we're already after the 2nd pulse */
 }
 
@@ -460,9 +475,8 @@ ISR_SHARED isr_SNIFF_ISO15693_ACA_AC0_VECT(void) {
 ISR_SHARED isr_SNIFF_ISO15693_CODEC_TIMER_TIMESTAMPS_CCA_VECT(void) {
 
     uint16_t TempRead = ADCA.CH1RES; /* Can't possibly be greater than 0xFFF since the dac has 12 bit res */
-    DACB.CH0DATA = TempRead - ANTENNA_LEVEL_OFFSET; /* Further increase DAC output after 3 pulses with value from PORTA Pin 2 (DEMOD-READER/2.3) */
-    DACB.CH0DATA &= -(DACB.CH0DATA <= TempRead); /* Branchfree saturating subtraction */
 
+    SetDacCh0Data(TempRead - ANTENNA_LEVEL_OFFSET); /* Further increase DAC output after 3 pulses with value from PORTA Pin 2 (DEMOD-READER/2.3) */
     CODEC_TIMER_TIMESTAMPS.INTCTRLB = TC_CCAINTLVL_OFF_gc; /* Disable this interrupt */
 }
 
@@ -480,8 +494,8 @@ ISR_SHARED isr_SNIFF_ISO15693_CODEC_TIMER_LOADMOD_CCA_VECT(void) {
 
         CODEC_TIMER_LOADMOD.INTCTRLB = TC_CCAINTLVL_OFF_gc; /* Disable all compare interrupts, including this one */
 
-        DACB.CH0DATA = DemodFloorNoiseLevel + (DemodFloorNoiseLevel >> 3); /* Restore DAC output (AC negative comparation threshold) to pre-AC0 interrupt update value */
-        DACB.CH0DATA |= -( (DACB.CH0DATA & 0xFFF) < DemodFloorNoiseLevel); /* Branchfree saturating addition */
+        SetDacCh0Data(DemodFloorNoiseLevel + (DemodFloorNoiseLevel >> 3)); /* Restore DAC output (AC negative comparation threshold) to pre-AC0 interrupt update value */
+
         ACA.AC0CTRL |= AC_INTLVL_HI_gc; /* Re-enable analog comparator interrupt to search for another pulse */
 
         CODEC_TIMER_TIMESTAMPS.INTCTRLB = TC_CCAINTLVL_HI_gc; /* Re enable CCA interrupt in case it was triggered and then is now disabled */
@@ -564,8 +578,8 @@ ISR_SHARED isr_SNIFF_ISO15693_CODEC_TIMER_LOADMOD_OVF_VECT(void) {
                     /* No SOC. The train of pulses was actually garbage. */
 
                     /* Restore DAC output to intial value */
-                    DACB.CH0DATA = DemodFloorNoiseLevel + (DemodFloorNoiseLevel >> 3);
-                    DACB.CH0DATA |= -( (DACB.CH0DATA & 0xFFF) < DemodFloorNoiseLevel); /* Branchfree saturating addition */
+                    SetDacCh0Data(DemodFloorNoiseLevel + (DemodFloorNoiseLevel >> 3));
+
 
                     /* Re enable AC interrupt */
                     ACA.AC0CTRL = AC_ENABLE_bm | AC_HSMODE_bm | AC_HYSMODE_LARGE_gc | AC_INTMODE_RISING_gc | AC_INTLVL_HI_gc;
@@ -692,6 +706,34 @@ void SniffISO15693CodecInit(void) {
     ReaderSniffInit();
 }
 
+/************************************************************
+    Function used by the Terminal command to display (GET)
+    the state of the Autothreshold Feature.
+************************************************************/
+bool SniffISO15693GetAutoThreshold(void){
+    return bAutoThreshold;
+}
+
+/************************************************************
+    Function used by the Application level to disable the
+    Autothreshold Feature.
+    If it is disabled: The threshold will be taken from
+    GlobalSettings.ActiveSettingPtr->ReaderThreshold
+************************************************************/
+void SniffISO15693CtrlAutoThreshold(bool enable){
+    bAutoThreshold = enable;
+    return;
+}
+
+/************************************************************
+    Function used by the Application level to get the FloorNoise
+    FloorNoise can be used to define the scanning range for the
+    Autocalibration.
+************************************************************/
+uint16_t SniffISO15693GetFloorNoise(void){
+    return DemodFloorNoiseLevel;
+}
+
 void SniffISO15693CodecDeInit(void) {
     /* Gracefully shutdown codec */
     CODEC_DEMOD_IN_PORT.INT0MASK = 0;

Firmware/Chameleon-Mini/Codec/SniffISO15693.h

@@ -32,6 +32,18 @@ void SniffISO15693CodecTask(void);
 /* Application Interface */
 void SniffISO15693CodecStart(void);
 void SniffISO15693CodecReset(void);
+/* Can be used by an application to disable */
+/* The auto-threshold algorithm */
+/* This is needed in corner cases - where the algo doesnt */
+/* find a proper threshold */
+/* In this case, the application can run an autocalibration session */
+void SniffISO15693CtrlAutoThreshold(bool enable);
+bool SniffISO15693GetAutoThreshold(void);
+
+/* Function is used to receive the measured FloorNoise */
+/* This is used to narrow down the range, which is considered for */
+/* Threshold */
+uint16_t SniffISO15693GetFloorNoise(void);
 
 /* Internal functions */
 INLINE void SNIFF_ISO15693_READER_EOC_VCD(void);