diff --git a/src/usb/hid/hid.c b/src/usb/hid/hid.c
index c44885c..42e80c0 100644
--- a/src/usb/hid/hid.c
+++ b/src/usb/hid/hid.c
@@ -125,6 +125,7 @@ void tud_hid_set_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t rep
   usb_rx(buffer, bufsize);
 }
 
+uint32_t last_cmd_time = 0, last_packet_time = 0;
 int ctap_error(uint8_t error) {
     ctap_resp = (CTAPHID_FRAME *)usb_get_tx();
     memset(ctap_resp, 0, sizeof(CTAPHID_FRAME));
@@ -134,6 +135,7 @@ int ctap_error(uint8_t error) {
     ctap_resp->init.data[0] = error;
     hid_write(64);
     usb_clear_rx();
+    last_packet_time = 0;
     return 0;
 }
 
@@ -145,10 +147,9 @@ uint32_t lock = 0;
 uint8_t thread_type = 0; //1 is APDU, 2 is CBOR
 extern void cbor_thread();
 extern void init_fido();
-uint32_t last_cmd_time = 0, last_packet_time = 0;
 
 int driver_process_usb_nopacket() {
-    if (last_packet_time+500 < board_millis()) {
+    if (last_packet_time > 0 && last_packet_time+500 < board_millis()) {
         ctap_error(CTAP1_ERR_MSG_TIMEOUT);
         last_packet_time = 0;
         msg_packet.len = msg_packet.current_len = 0;
@@ -165,14 +166,18 @@ int driver_process_usb_packet(uint16_t read) {
         memset(ctap_resp, 0, sizeof(CTAPHID_FRAME));
         if (ctap_req->cid == 0x0 || (ctap_req->cid == CID_BROADCAST && ctap_req->init.cmd != CTAPHID_INIT))
             return ctap_error(CTAP1_ERR_INVALID_CHANNEL);
-        if (board_millis() < lock && ctap_req->cid != last_req.cid && last_cmd_time+1000 > board_millis())
+        if (board_millis() < lock && ctap_req->cid != last_req.cid && last_cmd_time+100 > board_millis())
             return ctap_error(CTAP1_ERR_CHANNEL_BUSY);
         if (FRAME_TYPE(ctap_req) == TYPE_INIT)
         {
             if (MSG_LEN(ctap_req) > CTAP_MAX_PACKET_SIZE)
                 return ctap_error(CTAP1_ERR_INVALID_LEN);
-            if (msg_packet.len > 0 && last_req.cid != ctap_req->cid && last_cmd_time+1000 > board_millis()) //We are in a transaction
-                return ctap_error(CTAP1_ERR_CHANNEL_BUSY);
+            if (msg_packet.len > 0 && last_cmd_time+100 > board_millis() && ctap_req->init.cmd != CTAPHID_INIT) {
+                if (last_req.cid != ctap_req->cid) //We are in a transaction
+                    return ctap_error(CTAP1_ERR_CHANNEL_BUSY);
+                else
+                    return ctap_error(CTAP1_ERR_INVALID_SEQ);
+            }
             printf("command %x\n", FRAME_CMD(ctap_req));
             printf("len %d\n", MSG_LEN(ctap_req));
             msg_packet.len = msg_packet.current_len = 0;
@@ -196,9 +201,11 @@ int driver_process_usb_packet(uint16_t read) {
                 memcpy(msg_packet.data + msg_packet.current_len, ctap_req->cont.data, MIN(64 - 5, msg_packet.len - msg_packet.current_len));
                 msg_packet.current_len += MIN(64 - 5, msg_packet.len - msg_packet.current_len);
                 memcpy(&last_req, ctap_req, sizeof(CTAPHID_FRAME));
+                last_seq++;
             }
-            //else // Received a cont from another channel. Silently discard
-            last_seq++;
+            else if (last_cmd_time+100 > board_millis())
+                return ctap_error(CTAP1_ERR_CHANNEL_BUSY);
+
         }
 
         if (ctap_req->init.cmd == CTAPHID_INIT) {
@@ -219,7 +226,8 @@ int driver_process_usb_packet(uint16_t read) {
             ctap_resp->init.bcntl = 17;
             ctap_resp->init.bcnth = 0;
             driver_exec_finished(17);
-            printf("OK\n");
+            msg_packet.len = msg_packet.current_len = 0;
+            last_packet_time = 0;
         }
         else if (ctap_req->init.cmd == CTAPHID_WINK) {
             if (MSG_LEN(ctap_req) != 0) {
@@ -229,6 +237,8 @@ int driver_process_usb_packet(uint16_t read) {
             memcpy(ctap_resp, ctap_req, sizeof(CTAPHID_FRAME));
             sleep_ms(1000); //For blinking the device during 1 seg
             hid_write(64);
+            msg_packet.len = msg_packet.current_len = 0;
+            last_packet_time = 0;
         }
         else if ((last_cmd == CTAPHID_PING || last_cmd == CTAPHID_SYNC) && (msg_packet.len == 0 || (msg_packet.len == msg_packet.current_len && msg_packet.len > 0))) {
             ctap_resp = (CTAPHID_FRAME *)usb_get_tx();
@@ -241,6 +251,7 @@ int driver_process_usb_packet(uint16_t read) {
                 driver_exec_finished(MSG_LEN(ctap_req));
             }
             msg_packet.len = msg_packet.current_len = 0;
+            last_packet_time = 0;
         }
         else if (ctap_req->init.cmd == CTAPHID_LOCK) {
             if (MSG_LEN(ctap_req) != 1)
@@ -253,6 +264,8 @@ int driver_process_usb_packet(uint16_t read) {
             ctap_resp->cid = ctap_req->cid;
             ctap_resp->init.cmd = ctap_req->init.cmd;
             hid_write(64);
+            msg_packet.len = msg_packet.current_len = 0;
+            last_packet_time = 0;
         }
         else if (last_cmd == CTAPHID_MSG && (msg_packet.len == 0 || (msg_packet.len == msg_packet.current_len && msg_packet.len > 0))) {
 
@@ -266,7 +279,8 @@ int driver_process_usb_packet(uint16_t read) {
             else
                 apdu_sent = apdu_process(ctap_req->init.data, MSG_LEN(ctap_req));
             DEBUG_PAYLOAD(apdu.data, (int)apdu.nc);
-            msg_packet.len = msg_packet.current_len = 0; //Reset the transaction
+            msg_packet.len = msg_packet.current_len = 0;
+            last_packet_time = 0;
         }
         else if (last_cmd == CTAPHID_CBOR && (msg_packet.len == 0 || (msg_packet.len == msg_packet.current_len && msg_packet.len > 0))) {
 
@@ -277,7 +291,8 @@ int driver_process_usb_packet(uint16_t read) {
                 apdu_sent = cbor_process(msg_packet.data, msg_packet.len);
             else
                 apdu_sent = cbor_process(ctap_req->init.data, MSG_LEN(ctap_req));
-            msg_packet.len = msg_packet.current_len = 0; //Reset the transaction
+            msg_packet.len = msg_packet.current_len = 0;
+            last_packet_time = 0;
             if (apdu_sent < 0)
                 return ctap_error(-apdu_sent);
         }
@@ -293,7 +308,7 @@ int driver_process_usb_packet(uint16_t read) {
     return apdu_sent;
 }
 
-void driver_exec_timeout() {
+void send_keepalive() {
     ctap_resp = (CTAPHID_FRAME *)usb_get_tx();
     memset(ctap_resp, 0, sizeof(CTAPHID_FRAME));
     ctap_resp->cid = ctap_req->cid;
@@ -305,6 +320,10 @@ void driver_exec_timeout() {
     ctap_resp->init.data[0] = bck;
 }
 
+void driver_exec_timeout() {
+    send_keepalive();
+}
+
 uint8_t *driver_prepare_response() {
     ctap_resp = (CTAPHID_FRAME *)usb_get_tx();
     apdu.rdata = ctap_resp->init.data;