diff --git a/fido2/main.c b/fido2/main.c
index 35c4c6f..3849633 100644
--- a/fido2/main.c
+++ b/fido2/main.c
@@ -65,8 +65,6 @@ int main(int argc, char * argv[])
     usbhid_init();
     printf1(TAG_GEN,"init usb\n");
 
-    nfc_init();
-
     ctaphid_init();
     printf1(TAG_GEN,"init ctaphid\n");
 
diff --git a/fido2/u2f.c b/fido2/u2f.c
index eb24ae5..6d5e6eb 100644
--- a/fido2/u2f.c
+++ b/fido2/u2f.c
@@ -135,7 +135,7 @@ void u2f_request(struct u2f_request_apdu* req, CTAP_RESPONSE * resp)
 {
     uint32_t len = ((req->LC3) | ((uint32_t)req->LC2 << 8) | ((uint32_t)req->LC1 << 16));
 	
-	u2f_request_ex((APDU_HEADER *)req, &req[7], len, resp, false);	
+	u2f_request_ex((APDU_HEADER *)req, req->payload, len, resp, false);	
 }
 
 int8_t u2f_response_writeback(const uint8_t * buf, uint16_t len)
diff --git a/targets/stm32l432/src/ams.c b/targets/stm32l432/src/ams.c
index 1b2c87a..a342513 100644
--- a/targets/stm32l432/src/ams.c
+++ b/targets/stm32l432/src/ams.c
@@ -28,7 +28,7 @@ static void wait_for_rx()
 }
 
 
-static void ams_print_device(AMS_DEVICE * dev)
+void ams_print_device(AMS_DEVICE * dev)
 {
     printf1(TAG_NFC, "AMS_DEVICE:\r\n");
     printf1(TAG_NFC, "    io_conf:        %02x\r\n",dev->regs.io_conf);
@@ -252,7 +252,7 @@ void ams_print_int1(uint8_t int0)
     printf1(tag,"\r\n");
 }
 
-void ams_init()
+bool ams_init()
 {
 
     uint8_t block[4];
@@ -273,13 +273,19 @@ void ams_init()
     ams_write_command(AMS_CMD_DEFAULT);
     ams_write_command(AMS_CMD_CLEAR_BUFFER);
 
+	// check connection
+	uint8_t productType = ams_read_reg(AMS_REG_PRODUCT_TYPE);
+	if (!productType)
+	{
+		printf1(TAG_NFC,"Have no product type. Connection error.");
+		return false;
+	}
+	printf1(TAG_NFC,"Product type 0x%02x.", productType);
+	
     // enable tunneling mode and RF configuration
     ams_write_reg(AMS_REG_IC_CONF2, AMS_RFCFG_EN | AMS_TUN_MOD);
 
-    ams_read_eeprom_block(0, block);
-    printf1(TAG_NFC,"UID: "); dump_hex1(TAG_NFC,block,4);
-
-    ams_read_eeprom_block(0, block);
+    ams_read_eeprom_block(AMS_CONFIG_UID_ADDR, block);
     printf1(TAG_NFC,"UID: "); dump_hex1(TAG_NFC,block,4);
 
     ams_read_eeprom_block(AMS_CONFIG_BLOCK0_ADDR, block);
@@ -336,5 +342,6 @@ void ams_init()
         ams_read_eeprom_block(0x7F, block);
         printf1(TAG_NFC,"conf1: "); dump_hex1(TAG_NFC,block,4);
     }
-
+	
+	return true;
 }
diff --git a/targets/stm32l432/src/ams.h b/targets/stm32l432/src/ams.h
index 361cb0d..ad3b94f 100644
--- a/targets/stm32l432/src/ams.h
+++ b/targets/stm32l432/src/ams.h
@@ -1,8 +1,12 @@
+// AS3956 interface
+// https://ams.com/as3956
+// https://ams.com/documents/20143/36005/AS3956_DS000546_7-00.pdf
+
 #ifndef _AMS_H_
 #define _AMS_H_
 
 #include <stdint.h>
-#include <stdint.h>
+#include <stdbool.h>
 #include "stm32l4xx_ll_gpio.h"
 
 
@@ -35,7 +39,7 @@ 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)
 
-void ams_init();
+bool ams_init();
 
 void ams_read_buffer(uint8_t * data, int len);
 void ams_write_buffer(uint8_t * data, int len);
@@ -92,7 +96,14 @@ void ams_write_reg(uint8_t addr, uint8_t tx);
 #define AMS_REG_BUF2                    0x0c
     #define AMS_BUF_LEN_MASK            0x1f
     #define AMS_BUF_INVALID             0x80
+#define AMS_REG_BUF1                    0x0d
+// ... //
+#define AMS_REG_PRODUCT_TYPE            0x1c
+#define AMS_REG_PRODUCT_SUBTYPE         0x1d
+#define AMS_REG_VERSION_MAJOR           0x1e
+#define AMS_REG_VERSION_MINOR           0x1f
 
+#define AMS_CONFIG_UID_ADDR				0x00
 #define AMS_CONFIG_BLOCK0_ADDR          0x7e
 #define AMS_CONFIG_BLOCK1_ADDR          0x7f
 
diff --git a/targets/stm32l432/src/device.c b/targets/stm32l432/src/device.c
index 33d9113..b3fd58f 100644
--- a/targets/stm32l432/src/device.c
+++ b/targets/stm32l432/src/device.c
@@ -48,6 +48,7 @@ uint32_t __90_ms = 0;
 uint32_t __device_status = 0;
 uint32_t __last_update = 0;
 extern PCD_HandleTypeDef hpcd;
+bool haveNFC = false;
 
 #define IS_BUTTON_PRESSED()         (0  == (LL_GPIO_ReadInputPort(SOLO_BUTTON_PORT) & SOLO_BUTTON_PIN))
 
@@ -118,6 +119,12 @@ void device_init()
 #else
     flash_option_bytes_init(0);
 #endif
+    printf1(TAG_GEN,"init nfc\n");
+    haveNFC = nfc_init();
+	if (haveNFC)
+		printf1(TAG_GEN,"NFC OK.\n");
+	else
+		printf1(TAG_GEN,"NFC not found.\n");
 #endif
 
     printf1(TAG_GEN,"hello solo\r\n");
@@ -397,7 +404,8 @@ void device_manage()
     }
 #endif
 #ifndef IS_BOOTLOADER
-    nfc_loop();
+	if(haveNFC)
+		nfc_loop();
 #endif
 }
 
diff --git a/targets/stm32l432/src/nfc.c b/targets/stm32l432/src/nfc.c
index 1e2bfbf..75ba0bf 100644
--- a/targets/stm32l432/src/nfc.c
+++ b/targets/stm32l432/src/nfc.c
@@ -43,11 +43,12 @@ void nfc_state_init()
     NFC_STATE.block_num = 1;
 }
 
-void nfc_init()
+bool nfc_init()
 {
     nfc_state_init();
-    ams_init();
+    return ams_init();
 }
+
 void process_int0(uint8_t int0)
 {
 	
diff --git a/targets/stm32l432/src/nfc.h b/targets/stm32l432/src/nfc.h
index 0079ea4..b425b28 100644
--- a/targets/stm32l432/src/nfc.h
+++ b/targets/stm32l432/src/nfc.h
@@ -2,10 +2,11 @@
 #define _NFC_H_
 
 #include <stdint.h>
+#include <stdbool.h>
 #include "apdu.h"
 
 void nfc_loop();
-void nfc_init();
+bool nfc_init();
 
 typedef struct
 {