diff --git a/fido2/ctap.c b/fido2/ctap.c
index 553b20e..ecdff80 100644
--- a/fido2/ctap.c
+++ b/fido2/ctap.c
@@ -1536,7 +1536,7 @@ static void ctap_state_init()
     ctap_reset_rk();
 }
 
-void ctap_init(int init_pin)
+void ctap_init()
 {
     crypto_ecc256_init();
 
@@ -1591,7 +1591,7 @@ void ctap_init(int init_pin)
         exit(1);
     }
 
-    if (init_pin)
+    if (! device_is_nfc())
     {
         crypto_ecc256_make_key_pair(KEY_AGREEMENT_PUB, KEY_AGREEMENT_PRIV);
     }
diff --git a/fido2/ctap.h b/fido2/ctap.h
index a6db27d..a3a8783 100644
--- a/fido2/ctap.h
+++ b/fido2/ctap.h
@@ -267,7 +267,7 @@ uint8_t ctap_request(uint8_t * pkt_raw, int length, CTAP_RESPONSE * resp);
 int ctap_encode_der_sig(uint8_t const * const in_sigbuf, uint8_t * const out_sigder);
 
 // Run ctap related power-up procedures (init pinToken, generate shared secret)
-void ctap_init(int init_pin);
+void ctap_init();
 
 // Resets state between different accesses of different applications
 void ctap_reset_state();
diff --git a/targets/stm32l432/src/ams.c b/targets/stm32l432/src/ams.c
index 7b2438a..335758f 100644
--- a/targets/stm32l432/src/ams.c
+++ b/targets/stm32l432/src/ams.c
@@ -6,6 +6,7 @@
 #include "log.h"
 #include "util.h"
 #include "device.h"
+#include "nfc.h"
 
 static void flush_rx()
 {
@@ -269,11 +270,8 @@ void ams_print_int1(uint8_t int0)
 #endif
 }
 
-
-bool ams_init()
+void ams_init()
 {
-    uint8_t block[4];
-
     LL_GPIO_SetPinMode(SOLO_AMS_CS_PORT,SOLO_AMS_CS_PIN,LL_GPIO_MODE_OUTPUT);
     LL_GPIO_SetOutputPin(SOLO_AMS_CS_PORT,SOLO_AMS_CS_PIN);
 
@@ -284,85 +282,85 @@ bool ams_init()
 
     // delay(10);
     SELECT();
-    delay(2);
+    delay(1);
+}
 
-    // Needs to be disabled for passive operation
-    if (0)
-    // if (1)
+void ams_configure()
+{
+    // Should not be used during passive operation.
+    uint8_t block[4];
+
+	// check connection
+	uint8_t productType = ams_read_reg(AMS_REG_PRODUCT_TYPE);
+	if (productType != 0x14)
 	{
-    	// check connection
-    	uint8_t productType = ams_read_reg(AMS_REG_PRODUCT_TYPE);
-    	if (productType != 0x14)
-    	{
-    		printf1(TAG_NFC, "Have wrong product type [0x%02x]. AMS3956 connection error.\n", productType);
-    		return false;
-    	}
+		printf1(TAG_ERR, "Have wrong product type [0x%02x]. AMS3956 connection error.\n", productType);
+	}
 
-    	printf1(TAG_NFC,"AMS3956 product type 0x%02x.\n", productType);
+	printf1(TAG_NFC,"AMS3956 product type 0x%02x.\n", productType);
 
-        ams_read_eeprom_block(AMS_CONFIG_UID_ADDR, block);
-        printf1(TAG_NFC,"UID: 3F 14 02 - "); dump_hex1(TAG_NFC,block,4);
+    ams_read_eeprom_block(AMS_CONFIG_UID_ADDR, block);
+    printf1(TAG_NFC,"UID: 3F 14 02 - "); dump_hex1(TAG_NFC,block,4);
+
+    ams_read_eeprom_block(AMS_CONFIG_BLOCK0_ADDR, block);
+    printf1(TAG_NFC,"conf0: "); dump_hex1(TAG_NFC,block,4);
+
+    uint8_t sense1 = 0x44;
+    uint8_t sense2 = 0x00;
+    uint8_t selr   = 0x20;    // SAK
+
+    if(block[0] != sense1 || block[1] != sense2 || block[2] != selr)
+    {
+        printf1(TAG_NFC,"Writing config block 0\r\n");
+        block[0] = sense1;
+        block[1] = sense2;
+        block[2] = selr;
+        block[3] = 0x00;
+
+        ams_write_eeprom_block(AMS_CONFIG_BLOCK0_ADDR, block);
+        UNSELECT();
+        delay(10);
+        SELECT();
+        delay(10);
 
         ams_read_eeprom_block(AMS_CONFIG_BLOCK0_ADDR, block);
         printf1(TAG_NFC,"conf0: "); dump_hex1(TAG_NFC,block,4);
-
-        uint8_t sense1 = 0x44;
-        uint8_t sense2 = 0x00;
-        uint8_t selr   = 0x20;    // SAK
-
-        if(block[0] != sense1 || block[1] != sense2 || block[2] != selr)
-        {
-            printf1(TAG_NFC,"Writing config block 0\r\n");
-            block[0] = sense1;
-            block[1] = sense2;
-            block[2] = selr;
-            block[3] = 0x00;
-
-            ams_write_eeprom_block(AMS_CONFIG_BLOCK0_ADDR, block);
-            UNSELECT();
-            delay(10);
-            SELECT();
-            delay(10);
-
-            ams_read_eeprom_block(AMS_CONFIG_BLOCK0_ADDR, block);
-            printf1(TAG_NFC,"conf0: "); dump_hex1(TAG_NFC,block,4);
-        }
-
-        ams_read_eeprom_block(AMS_CONFIG_BLOCK1_ADDR, block);
-        printf1(TAG_NFC,"conf1: "); dump_hex1(TAG_NFC,block,4);
-
-        uint8_t ic_cfg1 = AMS_CFG1_OUTPUT_RESISTANCE_100 | AMS_CFG1_VOLTAGE_LEVEL_2V0;
-        uint8_t ic_cfg2 = AMS_CFG2_TUN_MOD;
-
-        if (block[0] != ic_cfg1 || block[1] != ic_cfg2)
-        {
-
-            printf1(TAG_NFC,"Writing config block 1\r\n");
-
-            ams_write_reg(AMS_REG_IC_CONF1,ic_cfg1);
-            ams_write_reg(AMS_REG_IC_CONF2,ic_cfg2);
-
-            // set IC_CFG1
-            block[0] = ic_cfg1;
-
-            // set IC_CFG2
-            block[1] = ic_cfg2;
-
-            // mask interrupt bits
-            block[2] = 0x80;
-            block[3] = 0;
-
-            ams_write_eeprom_block(AMS_CONFIG_BLOCK1_ADDR, block);
-
-            UNSELECT();
-            delay(10);
-            SELECT();
-            delay(10);
-
-            ams_read_eeprom_block(0x7F, block);
-            printf1(TAG_NFC,"conf1: "); dump_hex1(TAG_NFC,block,4);
-        }
     }
 
-	return true;
+    ams_read_eeprom_block(AMS_CONFIG_BLOCK1_ADDR, block);
+    printf1(TAG_NFC,"conf1: "); dump_hex1(TAG_NFC,block,4);
+
+    uint8_t ic_cfg1 = AMS_CFG1_OUTPUT_RESISTANCE_100 | AMS_CFG1_VOLTAGE_LEVEL_2V0;
+    uint8_t ic_cfg2 = AMS_CFG2_TUN_MOD;
+
+    if (block[0] != ic_cfg1 || block[1] != ic_cfg2)
+    {
+
+        printf1(TAG_NFC,"Writing config block 1\r\n");
+
+        ams_write_reg(AMS_REG_IC_CONF1,ic_cfg1);
+        ams_write_reg(AMS_REG_IC_CONF2,ic_cfg2);
+
+        // set IC_CFG1
+        block[0] = ic_cfg1;
+
+        // set IC_CFG2
+        block[1] = ic_cfg2;
+
+        // mask interrupt bits
+        block[2] = 0x80;
+        block[3] = 0;
+
+        ams_write_eeprom_block(AMS_CONFIG_BLOCK1_ADDR, block);
+
+        UNSELECT();
+        delay(10);
+        SELECT();
+        delay(10);
+
+        ams_read_eeprom_block(0x7F, block);
+        printf1(TAG_NFC,"conf1: "); dump_hex1(TAG_NFC,block,4);
+    }
+
+
 }
diff --git a/targets/stm32l432/src/ams.h b/targets/stm32l432/src/ams.h
index d8e3cad..ef701bf 100644
--- a/targets/stm32l432/src/ams.h
+++ b/targets/stm32l432/src/ams.h
@@ -39,7 +39,8 @@ typedef union
 #define SELECT() LL_GPIO_ResetOutputPin(SOLO_AMS_CS_PORT,SOLO_AMS_CS_PIN)
 #define UNSELECT() LL_GPIO_SetOutputPin(SOLO_AMS_CS_PORT,SOLO_AMS_CS_PIN)
 
-bool ams_init();
+void ams_init();
+void ams_configure();
 
 void ams_read_buffer(uint8_t * data, int len);
 void ams_write_buffer(uint8_t * data, int len);
diff --git a/targets/stm32l432/src/app.h b/targets/stm32l432/src/app.h
index 5753d14..8570d24 100644
--- a/targets/stm32l432/src/app.h
+++ b/targets/stm32l432/src/app.h
@@ -30,7 +30,7 @@
 // #define DISABLE_CTAPHID_WINK
 // #define DISABLE_CTAPHID_CBOR
 
-// #define ENABLE_SERIAL_PRINTING
+#define ENABLE_SERIAL_PRINTING
 
 #if defined(SOLO_HACKER)
 #define SOLO_PRODUCT_NAME "Solo Hacker " SOLO_VERSION
diff --git a/targets/stm32l432/src/device.c b/targets/stm32l432/src/device.c
index 7562c75..d65b7f8 100644
--- a/targets/stm32l432/src/device.c
+++ b/targets/stm32l432/src/device.c
@@ -60,7 +60,7 @@ void TIM6_DAC_IRQHandler()
     }
 #ifndef IS_BOOTLOADER
 	// NFC sending WTX if needs
-	if (haveNFC)
+	if (device_is_nfc())
 	{
 		WTX_timer_exec();
 	}
@@ -113,26 +113,32 @@ void device_init()
     hw_init(LOW_FREQUENCY);
     isLowFreq = 1;
 
-    printf1(TAG_NFC,"PWR->CR1: %04x\r\n", LL_PWR_GetRegulVoltageScaling());
+    haveNFC = nfc_init();
 
-    // hw_init(HIGH_FREQUENCY);
-    // isLowFreq = 0;
+    if (haveNFC)
+    {
+        printf1(TAG_NFC, "Have NFC\r\n");
+    }
+    else
+    {
+        printf1(TAG_NFC, "Have NO NFC\r\n");
+        hw_init(HIGH_FREQUENCY);
+
+        isLowFreq = 0;
+    }
 
     usbhid_init();
 
     ctaphid_init();
 
-    ctap_init( 0 );
+    ctap_init( !haveNFC );
 
-#ifndef IS_BOOTLOADER
 #if BOOT_TO_DFU
     flash_option_bytes_init(1);
 #else
     flash_option_bytes_init(0);
 #endif
-    printf1(TAG_GEN,"init nfc\n");
-    haveNFC = nfc_init();
-#endif
+
 
 }
 
@@ -430,7 +436,7 @@ void device_manage()
     }
 #endif
 #ifndef IS_BOOTLOADER
-	if(haveNFC)
+	// if(device_is_nfc())
 		nfc_loop();
 #endif
 }
diff --git a/targets/stm32l432/src/init.c b/targets/stm32l432/src/init.c
index 4834e5d..3e704ea 100644
--- a/targets/stm32l432/src/init.c
+++ b/targets/stm32l432/src/init.c
@@ -808,6 +808,8 @@ void init_debug_uart(void)
   /* Peripheral clock enable */
   LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_USART1);
 
+
+  LL_USART_DeInit(USART1);
   /**USART1 GPIO Configuration
   PB6   ------> USART1_TX
   PB7   ------> USART1_RX
diff --git a/targets/stm32l432/src/nfc.c b/targets/stm32l432/src/nfc.c
index dc66235..ab0ddf3 100644
--- a/targets/stm32l432/src/nfc.c
+++ b/targets/stm32l432/src/nfc.c
@@ -57,8 +57,23 @@ void nfc_state_init()
 
 bool nfc_init()
 {
+    uint32_t t1;
     nfc_state_init();
-    return ams_init();
+    ams_init();
+
+    // Detect if we are powered by NFC field by listening for a message for
+    // first 25 ms.
+    t1 = millis();
+    while ((millis() - t1) < 25)
+    {
+        if (nfc_loop() > 0)
+            return 1;
+    }
+
+    // Under USB power.  Configure AMS chip.
+    ams_configure();
+
+    return 0;
 }
 
 void process_int0(uint8_t int0)
@@ -699,88 +714,86 @@ void nfc_process_block(uint8_t * buf, unsigned int len)
     }
 }
 
-void nfc_loop()
+int nfc_loop()
 {
     uint8_t buf[32];
     AMS_DEVICE ams;
     int len = 0;
 
 
-    if (1)
+    read_reg_block(&ams);
+    uint8_t state = AMS_STATE_MASK & ams.regs.rfid_status;
+
+    if (state != AMS_STATE_SELECTED && state != AMS_STATE_SELECTEDX)
     {
-        read_reg_block(&ams);
-        uint8_t state = AMS_STATE_MASK & ams.regs.rfid_status;
+        // delay(1);  // sleep ?
+        return 0;
+    }
 
-        if (state != AMS_STATE_SELECTED && state != AMS_STATE_SELECTEDX)
-        {
-            // delay(1);  // sleep ?
-            return;
-        }
+    if (ams.regs.rfid_status)
+    {
+        // if (state != AMS_STATE_SENSE)
+        //      printf1(TAG_NFC,"    %s  x%02x\r\n", ams_get_state_string(ams.regs.rfid_status), state);
+    }
+    if (ams.regs.int0 & AMS_INT_INIT)
+    {
+        nfc_state_init();
+    }
+    if (ams.regs.int1)
+    {
+        // ams_print_int1(ams.regs.int1);
+    }
 
-        if (ams.regs.rfid_status)
+    if ((ams.regs.int0 & AMS_INT_RXE))
+    {
+        if (ams.regs.buffer_status2)
         {
-            // if (state != AMS_STATE_SENSE)
-            //      printf1(TAG_NFC,"    %s  x%02x\r\n", ams_get_state_string(ams.regs.rfid_status), state);
-        }
-        if (ams.regs.int0 & AMS_INT_INIT)
-        {
-            nfc_state_init();
-        }
-        if (ams.regs.int1)
-        {
-            // ams_print_int1(ams.regs.int1);
-        }
-
-        if ((ams.regs.int0 & AMS_INT_RXE))
-        {
-            if (ams.regs.buffer_status2)
+            if (ams.regs.buffer_status2 & AMS_BUF_INVALID)
             {
-                if (ams.regs.buffer_status2 & AMS_BUF_INVALID)
-                {
-                    printf1(TAG_NFC,"Buffer being updated!\r\n");
-                }
-                else
-                {
-                    len = ams.regs.buffer_status2 & AMS_BUF_LEN_MASK;
-                    ams_read_buffer(buf, len);
-                }
+                printf1(TAG_NFC,"Buffer being updated!\r\n");
+            }
+            else
+            {
+                len = ams.regs.buffer_status2 & AMS_BUF_LEN_MASK;
+                ams_read_buffer(buf, len);
             }
         }
+    }
 
-        if (len)
+    if (len)
+    {
+
+        // ISO 14443-3
+        switch(buf[0])
         {
+            case NFC_CMD_REQA:
+                printf1(TAG_NFC, "NFC_CMD_REQA\r\n");
+            break;
+            case NFC_CMD_WUPA:
+                printf1(TAG_NFC, "NFC_CMD_WUPA\r\n");
+            break;
+            case NFC_CMD_HLTA:
+                printf1(TAG_NFC, "HLTA/Halt\r\n");
+            break;
+            case NFC_CMD_RATS:
 
-            // ISO 14443-3
-            switch(buf[0])
-            {
-                case NFC_CMD_REQA:
-                    printf1(TAG_NFC, "NFC_CMD_REQA\r\n");
-                break;
-                case NFC_CMD_WUPA:
-                    printf1(TAG_NFC, "NFC_CMD_WUPA\r\n");
-                break;
-                case NFC_CMD_HLTA:
-                    printf1(TAG_NFC, "HLTA/Halt\r\n");
-                break;
-                case NFC_CMD_RATS:
+                answer_rats(buf[1]);
 
-                    answer_rats(buf[1]);
+                NFC_STATE.block_num = 1;
+				clear_ibuf();
+				WTX_clear();
+            break;
+            default:
 
-                    NFC_STATE.block_num = 1;
-    				clear_ibuf();
-    				WTX_clear();
-                break;
-                default:
-
-                    // ISO 14443-4
-                    nfc_process_block(buf,len);
+                // ISO 14443-4
+                nfc_process_block(buf,len);
 
 
-                break;
-            }
-
+            break;
         }
 
     }
 
+    return len;
+
 }
diff --git a/targets/stm32l432/src/nfc.h b/targets/stm32l432/src/nfc.h
index 2388018..a8627a2 100644
--- a/targets/stm32l432/src/nfc.h
+++ b/targets/stm32l432/src/nfc.h
@@ -5,7 +5,9 @@
 #include <stdbool.h>
 #include "apdu.h"
 
-void nfc_loop();
+// Return number of bytes read if any.
+int nfc_loop();
+
 bool nfc_init();
 
 typedef struct