small fix

targets/stm32l432/src/nfc.c

@@ -687,7 +687,14 @@ void nfc_process_block(uint8_t * buf, unsigned int len)
 
     if (IS_PPSS_CMD(buf[0]))
     {
-        printf1(TAG_NFC, "NFC_CMD_PPSS\r\n");
+        printf1(TAG_NFC, "NFC_CMD_PPSS [%d] 0x%02x\r\n", len, (len > 2) ? buf[2] : 0);
+        
+        if (buf[1] == 0x11 && (buf[2] & 0x0f) == 0x00) {
+            nfc_write_frame(buf, 1); // ack with correct start byte
+        } else {
+            printf1(TAG_NFC, "NFC_CMD_PPSS ERROR!!!\r\n");
+            nfc_write_frame("\x00", 1); // this should not happend. but iso14443-4 dont have NACK here, so just 0x00
+        }        
     }
     else if (IS_IBLOCK(buf[0]))
     {