diff --git a/F0-nolib/CANbus_stepper/src/canstepper.bin b/F0-nolib/CANbus_stepper/src/canstepper.bin
old mode 100755
new mode 100644
index 0ec29b9..f5d0891
Binary files a/F0-nolib/CANbus_stepper/src/canstepper.bin and b/F0-nolib/CANbus_stepper/src/canstepper.bin differ
diff --git a/F0-nolib/CANbus_stepper/src/proto.c b/F0-nolib/CANbus_stepper/src/proto.c
index 3f15f39..aafe933 100644
--- a/F0-nolib/CANbus_stepper/src/proto.c
+++ b/F0-nolib/CANbus_stepper/src/proto.c
@@ -105,6 +105,21 @@ static inline void showUIvals(){
     newline();
 }
 
+// check address & return 0 if wrong or address to roll to next non-digit
+static int chk485addr(const char *txt){
+    int32_t N;
+    int p = getnum(txt, &N);
+    if(!p){
+        USB_send("Not num\n");
+        return 0;
+    }
+    if(N == getBRDaddr()){
+        return p;
+    }
+    USB_send("Not me\n");
+    return 0;
+}
+
 /**
  * @brief cmd_parser - command parsing
  * @param txt   - buffer with commands & data
@@ -113,8 +128,20 @@ static inline void showUIvals(){
 void cmd_parser(const char *txt, uint8_t isUSB){
     sendbuf();
     USBcmd = isUSB;
+    int p = 0;
+    // we can't simple use &txt[p] as variable: it can be non-aligned by 4!!!
+    if(isUSB == TARGET_USART){ // check address and roll message to nearest non-space
+        p = chk485addr(txt);
+        if(!p) return;
+    }
+    // roll to non-space
+    char c;
+    while((c = txt[p])){
+        if(c == ' ' || c == '\t') ++p;
+        else break;
+    }
     //int16_t L = strlen(txt);
-    char _1st = txt[0];
+    char _1st = txt[p];
     switch(_1st){
         case 'a':
             showADCvals();
@@ -182,3 +209,53 @@ void printuhex(uint32_t val){
         }
     }
 }
+
+/**
+ * @brief getnum - read number from string omiting leading spaces
+ * @param buf (i) - string to process
+ * @param N (o)   - number read (or NULL for test)
+ * @return amount of symbols processed (or 0 if none)
+ */
+int getnum(const char *buf, int32_t *N){
+    char c;
+    int positive = -1, srd = 0;
+    int32_t val = 0;
+    while((c = *buf++)){
+        if(c == '\t' || c == ' '){
+            if(positive < 0){
+                ++srd;
+                continue; // beginning spaces
+            }
+            else break; // spaces after number
+        }
+        if(c == '-'){
+            if(positive < 0){
+                ++srd;
+                positive = 0;
+                continue;
+            }else break; // there already was `-` or number
+        }
+        if(c < '0' || c > '9') break;
+        ++srd;
+        if(positive < 0) positive = 1;
+        val = val * 10 + (int32_t)(c - '0');
+    }
+    if(positive != -1){
+        if(positive == 0){
+            if(val == 0) return 0; // single '-' or -0000
+            val = -val;
+        }
+        if(N) *N = val;
+    }else return 0;
+uint8_t uold = USBcmd;
+USBcmd = TARGET_USB;
+addtobuf("Got num: ");
+if(val < 0){bufputchar('-'); val = -val;}
+printu(val);
+addtobuf(", N=");
+printu(srd);
+newline();
+sendbuf();
+USBcmd = uold;
+    return srd;
+}
diff --git a/F0-nolib/CANbus_stepper/src/proto.h b/F0-nolib/CANbus_stepper/src/proto.h
index 8283ec8..2dfbcb6 100644
--- a/F0-nolib/CANbus_stepper/src/proto.h
+++ b/F0-nolib/CANbus_stepper/src/proto.h
@@ -40,9 +40,11 @@
 void cmd_parser(const char *buf, uint8_t isUSB);
 void addtobuf(const char *txt);
 void bufputchar(char ch);
+void sendbuf();
 void printu(uint32_t val);
 void printuhex(uint32_t val);
-void sendbuf();
+int getnum(const char *buf, int32_t *N);
+
 #define TARGET_USB   1
 #define TARGET_USART 0
 void buftgt(uint8_t isUSB);
diff --git a/F0-nolib/CANbus_stepper/src/usart.c b/F0-nolib/CANbus_stepper/src/usart.c
index b176127..f9a1f1e 100644
--- a/F0-nolib/CANbus_stepper/src/usart.c
+++ b/F0-nolib/CANbus_stepper/src/usart.c
@@ -111,6 +111,7 @@ void usart_send_blocking(const char *str, int len){
         USARTX -> TDR = *str++;
         while(!(USARTX->ISR & USART_ISR_TXE)){IWDG->KR = IWDG_REFRESH;}
     }
+    // wait for transfer complete to switch into Rx
     while(!(USARTX->ISR & USART_ISR_TC)){IWDG->KR = IWDG_REFRESH;}
     _485_Rx();
 }
diff --git a/F0-nolib/Chiller/chiller.bin b/F0-nolib/Chiller/chiller.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/F0_testbrd/pl2303.bin b/F0-nolib/F0_testbrd/pl2303.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/QuadEncoder/encoder.bin b/F0-nolib/QuadEncoder/encoder.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/Servo/servo.bin b/F0-nolib/Servo/servo.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/TM1637/tm1637.bin b/F0-nolib/TM1637/tm1637.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/USBHID/usbhid.bin b/F0-nolib/USBHID/usbhid.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/blink/blink.bin b/F0-nolib/blink/blink.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/canbus/src/canbus.bin b/F0-nolib/canbus/src/canbus.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/htu21d_nucleo/usart.bin b/F0-nolib/htu21d_nucleo/usart.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/morze/morze.bin b/F0-nolib/morze/morze.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/pl2303/pl2303.bin b/F0-nolib/pl2303/pl2303.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/tsys01_nucleo/tsys01.bin b/F0-nolib/tsys01_nucleo/tsys01.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/uart_blink/uartblink.bin b/F0-nolib/uart_blink/uartblink.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/uart_blink_dma/uartblink.bin b/F0-nolib/uart_blink_dma/uartblink.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/uart_nucleo/usart.bin b/F0-nolib/uart_nucleo/usart.bin
old mode 100644
new mode 100755
diff --git a/F0-nolib/usbcdc/usbcan.bin b/F0-nolib/usbcdc/usbcan.bin
old mode 100644
new mode 100755
diff --git a/F0/blink/blink.bin b/F0/blink/blink.bin
old mode 100644
new mode 100755
diff --git a/F0/uart/uart.bin b/F0/uart/uart.bin
old mode 100644
new mode 100755
diff --git a/F1-nolib/CDC_ACM/cdcacm.bin b/F1-nolib/CDC_ACM/cdcacm.bin
old mode 100644
new mode 100755
index 77ff49d..ccafeba
Binary files a/F1-nolib/CDC_ACM/cdcacm.bin and b/F1-nolib/CDC_ACM/cdcacm.bin differ
diff --git a/F1-nolib/CDC_ACM/main.c b/F1-nolib/CDC_ACM/main.c
index 4bbbacd..24f5653 100644
--- a/F1-nolib/CDC_ACM/main.c
+++ b/F1-nolib/CDC_ACM/main.c
@@ -53,7 +53,7 @@ void iwdg_setup(){
     while(IWDG->SR){if(--tmout == 0) break;} /* (5) */
     IWDG->KR = IWDG_REFRESH; /* (6) */
 }
-
+/*
 char *parse_cmd(char *buf){
     IWDG->KR = IWDG_REFRESH;
     if(buf[1] != '\n') return buf;
@@ -93,43 +93,55 @@ char *parse_cmd(char *buf){
         break;
     }
     return NULL;
+}*/
+
+/*
+char *get_USB(){
+    static char tmpbuf[65];
+    int x = USB_receive(tmpbuf, 64);
+    tmpbuf[x] = 0;
+    if(!x) return NULL;
+    return tmpbuf;
 }
 
 // usb getline
 char *get_USB(){
-    static char tmpbuf[512], *curptr = tmpbuf;
-    static int rest = 511;
+    static char tmpbuf[128], *curptr = tmpbuf;
+    static int rest = 127;
     int x = USB_receive(curptr, rest);
     curptr[x] = 0;
     if(!x) return NULL;
-    MSG(tmpbuf);
     if(curptr[x-1] == '\n'){
+        //DBG("Got \\n");
         curptr = tmpbuf;
-        rest = 511;
+        rest = 127;
         return tmpbuf;
     }
     curptr += x; rest -= x;
     if(rest <= 0){ // buffer overflow
+        //DBG("Buffer full");
         curptr = tmpbuf;
-        rest = 511;
+        rest = 127;
+        return tmpbuf;
     }
     return NULL;
-}
+}*/
 
 
-uint32_t newrate = 0;
+static uint32_t newrate = 0;
+// redefine weak handlers
 void linecoding_handler(usb_LineCoding *lcd){
     newrate = lcd->dwDTERate;
 }
-uint16_t cl = 0xffff;
+static uint16_t cl = 0xffff;
 void clstate_handler(uint16_t val){
     cl = val;
 }
-int8_t br = 0;
+static int8_t br = 0;
 void break_handler(){
     br = 1;
 }
-
+/*
 char *u2str(uint32_t val){
     static char strbuf[11];
     char *bufptr = &strbuf[10];
@@ -143,7 +155,7 @@ char *u2str(uint32_t val){
         }
     }
     return bufptr;
-}
+}*/
 
 int main(void){
     uint32_t lastT = 0;
@@ -154,6 +166,7 @@ int main(void){
     hw_setup();
     USBPU_OFF();
     usart_setup();
+    DBG("Start");
     if(RCC->CSR & RCC_CSR_IWDGRSTF){ // watchdog reset occured
         SEND("WDGRESET=1"); newline();
     }
@@ -163,7 +176,7 @@ int main(void){
     RCC->CSR |= RCC_CSR_RMVF; // remove reset flags
 
     USB_setup();
-    //iwdg_setup();
+    iwdg_setup();
     USBPU_ON();
 
     //uint32_t ctr = 0;
@@ -173,25 +186,30 @@ int main(void){
             LED_blink(LED0);
             lastT = Tms;
             transmit_tbuf();
-/*
-            if(usbON){
-                USB_send("String #");
-                char *s = u2str(ctr++);
-                USB_send(s);
-                USB_send("\n");
-            }*/
         }
         usb_proc();
-        char *txt, *ans;
-        if((txt = get_USB())){
-            ans = parse_cmd(txt);
-            if(ans) USB_send(ans);
+        if(bufovr){
+            bufovr = 0;
+            USB_send((uint8_t*)"USART overflow!\n", 16);
+        }
+        uint8_t tmpbuf[USB_RXBUFSZ], *txt;
+        uint16_t x = USB_receive(tmpbuf);
+        if(x){
+            //for(int _ = 0; _ < 7000000; ++_)nop();
+            //USB_send(tmpbuf, x);
+            usart_senddata(tmpbuf, x);
+            //transmit_tbuf();
+           /*char *ans = parse_cmd(txt);
+           if(ans) USB_send(ans);*/
+        }
+        if((x = usart_get(&txt))){
+            USB_send(txt, x);
         }
         int n = 0;
         if(newrate){SEND("new speed: "); printu(newrate); n = 1; newrate = 0;}
         if(cl!=0xffff){SEND("controls: "); printuhex(cl); n = 1; cl = 0xffff;}
         if(br){SEND("break"); n = 1; br = 0;}
-        if(n) newline();
+        if(n){newline(); transmit_tbuf();}
     }
     return 0;
 }
diff --git a/F1-nolib/CDC_ACM/usart.c b/F1-nolib/CDC_ACM/usart.c
index 7553e0f..d631476 100644
--- a/F1-nolib/CDC_ACM/usart.c
+++ b/F1-nolib/CDC_ACM/usart.c
@@ -19,8 +19,8 @@
  * MA 02110-1301, USA.
  */
 #include "stm32f1.h"
-#include "sync.h"
 #include "usart.h"
+#include "usb.h"
 
 extern volatile uint32_t Tms;
 static volatile int idatalen[2] = {0,0}; // received data line length (including '\n')
@@ -33,85 +33,93 @@ int linerdy = 0,        // received data ready
     txrdy = 1           // transmission done
 ;
 
-static mutex_t the_mutex = MUTEX_UNLOCKED; // mutex for sending messages
-
 static int rbufno = 0, tbufno = 0; // current rbuf/tbuf numbers
-static char rbuf[2][UARTBUFSZI], tbuf[2][UARTBUFSZO]; // receive & transmit buffers
-static char *recvdata = NULL;
+static uint8_t rbuf[2][UARTBUFSZI], tbuf[2][UARTBUFSZO]; // receive & transmit buffers
+static uint8_t *recvdata = NULL;
 
 /**
  * return length of received data (without trailing zero)
  */
-int usart_getline(char **line){
+uint16_t usart_get(uint8_t **line){
+    if(!line) return 0;
+    *line = NULL;
     if(bufovr){
         bufovr = 0;
         linerdy = 0;
         return 0;
     }
+    if(!linerdy) return 0;
+    USART1->CR1 &= ~USART_CR1_RXNEIE; // disallow Rx IRQ
+    dlen = idatalen[rbufno];
+    recvdata = rbuf[rbufno];
+    // prepare other buffer
+    rbufno = !rbufno;
+    idatalen[rbufno] = 0;
+    recvdata[dlen] = 0;
     *line = recvdata;
     linerdy = 0;
+    USART1->CR1 |= USART_CR1_RXNEIE; // allow Rx IRQ
     return dlen;
 }
 
 // transmit current tbuf and swap buffers
-void transmit_tbuf(){
-    uint32_t tmout = 160000;
-    mutex_lock(&the_mutex);
+int transmit_tbuf(){
+    uint32_t tmout = 7200;
     while(!txrdy){ // wait for previos buffer transmission
         IWDG->KR = IWDG_REFRESH;
         if(--tmout == 0){
-            mutex_unlock(&the_mutex);
-            return;
+            //DMA1_Channel4->CCR &= ~DMA_CCR_EN;
+            //txrdy = 1;
+            return 1;
         }
     }
-    register int l = odatalen[tbufno];
+    int l = odatalen[tbufno];
     if(!l){
-        mutex_unlock(&the_mutex);
-        return;
+        return 0;
     }
-    txrdy = 0;
-    odatalen[tbufno] = 0;
     DMA1_Channel4->CCR &= ~DMA_CCR_EN;
     DMA1_Channel4->CMAR = (uint32_t) tbuf[tbufno]; // mem
     DMA1_Channel4->CNDTR = l;
-    DMA1_Channel4->CCR |= DMA_CCR_EN;
     tbufno = !tbufno;
-    mutex_unlock(&the_mutex);
+    odatalen[tbufno] = 0;
+    txrdy = 0;
+    DMA1_Channel4->CCR |= DMA_CCR_EN;
+    return 0;
 }
 
 void usart_putchar(const char ch){
-    mutex_lock(&the_mutex);
-    if(odatalen[tbufno] == UARTBUFSZO){
-        mutex_unlock(&the_mutex);
-        //return;
-        transmit_tbuf();
-        mutex_lock(&the_mutex);
-    }
     tbuf[tbufno][odatalen[tbufno]++] = ch;
-    mutex_unlock(&the_mutex);
+    if(odatalen[tbufno] >= UARTBUFSZO){
+        while(transmit_tbuf());
+    }
 }
 
 void usart_send(const char *str){
-    uint32_t x = 512;
-    mutex_lock(&the_mutex);
-    while(*str && --x){
-        if(odatalen[tbufno] == UARTBUFSZO){
-            mutex_unlock(&the_mutex);
-            //return;
-            transmit_tbuf();
-            mutex_lock(&the_mutex);
-        }
+    if(!str) return;
+    while(*str){
         tbuf[tbufno][odatalen[tbufno]++] = *str++;
+        if(odatalen[tbufno] >= UARTBUFSZO){
+            while(transmit_tbuf());
+        }
+    }
+}
+
+/**
+ * @brief usart_senddata - the same as usart_send, but with given length
+ */
+void usart_senddata(const uint8_t *str, uint16_t len){
+    while(len--){
+        tbuf[tbufno][odatalen[tbufno]++] = *str++;
+        if(odatalen[tbufno] >= UARTBUFSZO){
+            while(transmit_tbuf());
+        }
     }
-    mutex_unlock(&the_mutex);
 }
 
 void newline(){
     usart_putchar('\n');
-    //transmit_tbuf();
 }
 
-
 /*
  * USART speed: baudrate = Fck/(USARTDIV)
  * USARTDIV stored in USART->BRR
@@ -135,8 +143,8 @@ void usart_setup(){
     NVIC_EnableIRQ(DMA1_Channel4_IRQn);
     NVIC_SetPriority(USART1_IRQn, 0);
     // setup usart1
-    //USART1->BRR = 72000000 / 115200;
-    USART1->BRR = 24; // 3000000
+    USART1->BRR = 72000000 / 115200;
+    //USART1->BRR = 24; // 3000000
     USART1->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE; // 1start,8data,nstop; enable Rx,Tx,USART
     while(!(USART1->SR & USART_SR_TC)){ // polling idle frame Transmission
         IWDG->KR = IWDG_REFRESH;
@@ -165,18 +173,11 @@ void usart1_isr(){
         uint8_t rb = USART1->DR;
         if(idatalen[rbufno] < UARTBUFSZI){ // put next char into buf
             rbuf[rbufno][idatalen[rbufno]++] = rb;
-            if(rb == '\n'){ // got newline - line ready
-                linerdy = 1;
-                dlen = idatalen[rbufno];
-                recvdata = rbuf[rbufno];
-                // prepare other buffer
-                rbufno = !rbufno;
-                idatalen[rbufno] = 0;
-                #ifdef CHECK_TMOUT
-                // clear timeout at line end
-                tmout = 0;
-                #endif
-            }
+            linerdy = 1; // ready for reading
+            #ifdef CHECK_TMOUT
+            // clear timeout at line end
+            tmout = 0;
+            #endif
         }else{ // buffer overrun
             bufovr = 1;
             idatalen[rbufno] = 0;
@@ -187,6 +188,7 @@ void usart1_isr(){
     }
 }
 
+
 // print 32bit unsigned int
 void printu(uint32_t val){
     char bufa[11], bufb[10];
@@ -222,9 +224,9 @@ void printuhex(uint32_t val){
         }
     }
 }
-
+/*
 // dump memory buffer
-void hexdump(uint8_t *arr, uint16_t len){
+void hexdump(const uint8_t *arr, uint16_t len){
     for(uint16_t l = 0; l < len; ++l, ++arr){
         for(int16_t j = 1; j > -1; --j){
             register uint8_t half = (*arr >> (4*j)) & 0x0f;
@@ -235,12 +237,10 @@ void hexdump(uint8_t *arr, uint16_t len){
         else if(l & 1) usart_putchar(' ');
     }
 }
-
+*/
 void dma1_channel4_isr(){
-    if(DMA1->ISR & DMA_ISR_TCIF4){ // Tx
-        DMA1->IFCR = DMA_IFCR_CTCIF4; // clear TC flag
-        txrdy = 1;
-    }
+    DMA1->IFCR = DMA_IFCR_CTCIF4; // clear TC flag
+    txrdy = 1;
 }
 
 /*
diff --git a/F1-nolib/CDC_ACM/usart.h b/F1-nolib/CDC_ACM/usart.h
index 0b5307d..e64ee73 100644
--- a/F1-nolib/CDC_ACM/usart.h
+++ b/F1-nolib/CDC_ACM/usart.h
@@ -24,8 +24,8 @@
 #define __USART_H__
 
 // input and output buffers size
-#define UARTBUFSZI  (16)
-#define UARTBUFSZO  (512)
+#define UARTBUFSZI  (64)
+#define UARTBUFSZO  (64)
 // timeout between data bytes
 #ifndef TIMEOUT_MS
 #define TIMEOUT_MS (1500)
@@ -51,14 +51,15 @@
 
 extern int linerdy, bufovr, txrdy;
 
-void transmit_tbuf();
+int transmit_tbuf();
 void usart_setup();
-int usart_getline(char **line);
+uint16_t usart_get(uint8_t **line);
 void usart_send(const char *str);
+void usart_senddata(const uint8_t *str, uint16_t len);
 void newline();
 void usart_putchar(const char ch);
 void printu(uint32_t val);
 void printuhex(uint32_t val);
-void hexdump(uint8_t *arr, uint16_t len);
+void hexdump(const uint8_t *arr, uint16_t len);
 
 #endif // __USART_H__
diff --git a/F1-nolib/CDC_ACM/usb.c b/F1-nolib/CDC_ACM/usb.c
index 9333be8..45eabfa 100644
--- a/F1-nolib/CDC_ACM/usb.c
+++ b/F1-nolib/CDC_ACM/usb.c
@@ -24,44 +24,32 @@
 #include "usb_lib.h"
 #include "usart.h"
 
-// incoming buffer size
-#define IDATASZ     (256)
-static uint8_t incoming_data[IDATASZ];
-static uint8_t ovfl = 0;
-static uint16_t idatalen = 0;
-static volatile uint8_t tx_succesfull = 0;
+static volatile uint8_t tx_succesfull = 1;
 
 // interrupt IN handler (never used?)
-static uint16_t EP1_Handler(ep_t ep){
-    if (ep.rx_flag){
-        ep.status = SET_VALID_TX(ep.status);
-        ep.status = KEEP_STAT_RX(ep.status);
-    }else if (ep.tx_flag){
-        ep.status = SET_VALID_RX(ep.status);
-        ep.status = SET_STALL_TX(ep.status);
-    }
-    return ep.status;
+static void EP1_Handler(){
+    DBG("EP1");
+    uint16_t epstatus = KEEP_DTOG(USB->EPnR[1]);
+    if(RX_FLAG(epstatus)) epstatus = (epstatus & ~USB_EPnR_STAT_TX) ^ USB_EPnR_STAT_RX; // set valid RX
+    else epstatus = epstatus & ~(USB_EPnR_STAT_TX|USB_EPnR_STAT_RX);
+    // clear CTR
+    epstatus = (epstatus & ~(USB_EPnR_CTR_RX|USB_EPnR_CTR_TX));
+    USB->EPnR[1] = epstatus;
 }
 
-// data IN/OUT handler
-static uint16_t EP23_Handler(ep_t ep){
-    if(ep.rx_flag){
-        int rd = ep.rx_cnt, rest = IDATASZ - idatalen;
-        if(rd){
-            if(rd <= rest){
-                idatalen += EP_Read(2, (uint16_t*)&incoming_data[idatalen]);
-                ovfl = 0;
-            }else{
-                ep.status = SET_NAK_RX(ep.status);
-                ovfl = 1;
-                return ep.status;
-            }
-        }
-    }else if (ep.tx_flag){
-        tx_succesfull = 1;
-    }
-    ep.status = SET_VALID_RX(ep.status);
-    return ep.status;
+// data IN/OUT handlers
+static void transmit_Handler(){ // EP3IN
+    tx_succesfull = 1;
+    uint16_t epstatus = KEEP_DTOG_STAT(USB->EPnR[3]);
+    // clear CTR keep DTOGs & STATs
+    USB->EPnR[3] = (epstatus & ~(USB_EPnR_CTR_TX)); // clear TX ctr
+}
+
+static uint8_t rxNE = 0;
+static void receive_Handler(){ // EP2OUT
+    rxNE = 1;
+    uint16_t epstatus = KEEP_DTOG_STAT(USB->EPnR[2]);
+    USB->EPnR[2] = (epstatus & ~(USB_EPnR_CTR_RX)); // clear RX ctr
 }
 
 void USB_setup(){
@@ -76,17 +64,79 @@ void USB_setup(){
     USB->ISTR   = 0;
     USB->CNTR   = USB_CNTR_RESETM | USB_CNTR_WKUPM; // allow only wakeup & reset interrupts
     NVIC_EnableIRQ(USB_LP_CAN1_RX0_IRQn);
-    //NVIC_EnableIRQ(USB_HP_CAN1_TX_IRQn );
+    DBG("USB irq enabled");
 }
 
+
+static int usbwr(const uint8_t *buf, uint16_t l){
+    uint32_t ctra = 1000000;
+    while(--ctra && tx_succesfull == 0){
+        IWDG->KR = IWDG_REFRESH;
+    }
+    tx_succesfull = 0;
+    EP_Write(3, buf, l);
+    ctra = 1000000;
+    while(--ctra && tx_succesfull == 0){
+        IWDG->KR = IWDG_REFRESH;
+    }
+    if(tx_succesfull == 0){usbON = 0; DBG("USB disconnected"); return 1;} // usb is OFF?
+    return 0;
+}
+
+static uint8_t usbbuff[USB_TXBUFSZ-1]; // temporary buffer (63 - to prevent need of ZLP)
+static uint8_t buflen = 0; // amount of symbols in usbbuff
+
+// send next up to 64 bytes of data in usbbuff
+static void send_next(){
+    if(!buflen || !tx_succesfull) return;
+    tx_succesfull = 0;
+    EP_Write(3, usbbuff, buflen);
+    buflen = 0;
+}
+
+// unblocking sending - just fill a buffer
+void USB_send(const uint8_t *buf, uint16_t len){
+    if(!usbON || !len) return;
+    if(len > USB_TXBUFSZ-1){
+        USB_send_blk(buf, len);
+        return;
+    }
+    if(len > USB_TXBUFSZ-1 - buflen){
+        usbwr(usbbuff, buflen);
+        buflen = 0;
+    }
+    while(len--) usbbuff[buflen++] = *buf++;
+}
+
+// blocking sending
+void USB_send_blk(const uint8_t *buf, uint16_t len){
+    if(!usbON || !len) return; // USB disconnected
+    if(buflen){
+        usbwr(usbbuff, buflen);
+        buflen = 0;
+    }
+    int needzlp = 0;
+    while(len){
+        if(len == USB_TXBUFSZ) needzlp = 1;
+        uint16_t s = (len > USB_TXBUFSZ) ? USB_TXBUFSZ : len;
+        if(usbwr(buf, s)) return;
+        len -= s;
+        buf += s;
+    }  
+    if(needzlp){
+        usbwr(NULL, 0);
+    }
+}
+
+
 void usb_proc(){
     switch(USB_Dev.USB_Status){
         case USB_STATE_CONFIGURED:
             // make new BULK endpoint
             // Buffer have 1024 bytes, but last 256 we use for CAN bus (30.2 of RM: USB main features)
             EP_Init(1, EP_TYPE_INTERRUPT, USB_EP1BUFSZ, 0, EP1_Handler); // IN1 - transmit
-            EP_Init(2, EP_TYPE_BULK, 0, USB_RXBUFSZ, EP23_Handler); // OUT2 - receive data
-            EP_Init(3, EP_TYPE_BULK, USB_TXBUFSZ, 0, EP23_Handler); // IN3 - transmit data
+            EP_Init(2, EP_TYPE_BULK, 0, USB_RXBUFSZ, receive_Handler); // OUT2 - receive data
+            EP_Init(3, EP_TYPE_BULK, USB_TXBUFSZ, 0, transmit_Handler); // IN3 - transmit data
             USB_Dev.USB_Status = USB_STATE_CONNECTED;
             DBG("Connected");
         break;
@@ -96,55 +146,25 @@ void usb_proc(){
                 DBG("def/adr");
                 usbON = 0;
             }
-        default:
-            return;
-    }
-}
-
-void USB_send(const char *buf){
-    if(!usbON) return; // USB disconnected
-    uint16_t l = 0, ctr = 0;
-    const char *p = buf;
-    while(*p++) ++l;
-    while(l){
-        uint16_t s = (l > USB_TXBUFSZ) ? USB_TXBUFSZ : l;
-        tx_succesfull = 0;
-        EP_Write(3, (uint8_t*)&buf[ctr], s);
-        uint32_t ctra = 1000000;
-        while(--ctra && tx_succesfull == 0){
-            IWDG->KR = IWDG_REFRESH;
-        }
-        if(tx_succesfull == 0){usbON = 0; DBG("USB disconnected"); return;} // usb is OFF?
-        l -= s;
-        ctr += s;
+        break;
+        default: // USB_STATE_CONNECTED - send next data portion
+            if(!usbON) return;
+            send_next();
     }
 }
 
 /**
  * @brief USB_receive
- * @param buf (i) - buffer for received data
- * @param bufsize - its size
+ * @param buf (i) - buffer[64] for received data
  * @return amount of received bytes
  */
-int USB_receive(char *buf, int bufsize){
-    if(bufsize < 1 || !idatalen) return 0;
-    uint32_t oldcntr = USB->CNTR;
-    USB->CNTR = 0;
-    int sz = (idatalen > bufsize) ? bufsize : idatalen, rest = idatalen - sz;
-    for(int i = 0; i < sz; ++i) buf[i] = incoming_data[i];
-    if(rest > 0){
-        uint8_t *ptr = &incoming_data[sz];
-        for(int i = 0; i < rest; ++i) incoming_data[i] = *ptr++;
-        idatalen = rest;
-    }else idatalen = 0;
-    if(ovfl){
-        EP23_Handler(endpoints[2]);
-        uint16_t epstatus = USB->EPnR[2];
-        epstatus = CLEAR_DTOG_RX(epstatus);
-        epstatus = SET_VALID_RX(epstatus);
-        USB->EPnR[2] = epstatus;
-    }
-    USB->CNTR = oldcntr;
+uint8_t USB_receive(uint8_t *buf){
+    if(!usbON || !rxNE) return 0;
+    //DBG("Get data");
+    uint8_t sz = EP_Read(2, (uint16_t*)buf);
+    uint16_t epstatus = KEEP_DTOG(USB->EPnR[2]);
+    // keep stat_tx & set ACK rx
+    USB->EPnR[2] = (epstatus & ~(USB_EPnR_STAT_TX)) ^ USB_EPnR_STAT_RX;
+    rxNE = 0;
     return sz;
 }
-
diff --git a/F1-nolib/CDC_ACM/usb.h b/F1-nolib/CDC_ACM/usb.h
index a780e5f..c9d315d 100644
--- a/F1-nolib/CDC_ACM/usb.h
+++ b/F1-nolib/CDC_ACM/usb.h
@@ -26,11 +26,10 @@
 
 #include "hardware.h"
 
-#define BUFFSIZE   (64)
-
 void USB_setup();
 void usb_proc();
-void USB_send(const char *buf);
-int USB_receive(char *buf, int bufsize);
+void USB_send(const uint8_t *buf, uint16_t len);
+void USB_send_blk(const uint8_t *buf, uint16_t len);
+uint8_t USB_receive(uint8_t *buf);
 
 #endif // __USB_H__
diff --git a/F1-nolib/CDC_ACM/usb_defs.h b/F1-nolib/CDC_ACM/usb_defs.h
index 7be62b1..1ac3dd0 100644
--- a/F1-nolib/CDC_ACM/usb_defs.h
+++ b/F1-nolib/CDC_ACM/usb_defs.h
@@ -93,18 +93,6 @@ typedef struct {
     __IO uint32_t BTABLE;
 } USB_TypeDef;
 
-/*
-typedef struct{
-    __IO uint16_t USB_ADDR_TX;
-    __IO uint16_t res1;
-    __IO uint16_t USB_COUNT_TX;
-    __IO uint16_t res2;
-    __IO uint16_t USB_ADDR_RX;
-    __IO uint16_t res3;
-    __IO uint16_t USB_COUNT_RX;
-    __IO uint16_t res4;
-} USB_EPDATA_TypeDef;*/
-
 typedef struct{
     __IO uint32_t USB_ADDR_TX;
     __IO uint32_t USB_COUNT_TX;
diff --git a/F1-nolib/CDC_ACM/usb_lib.c b/F1-nolib/CDC_ACM/usb_lib.c
index f34d37e..943fde7 100644
--- a/F1-nolib/CDC_ACM/usb_lib.c
+++ b/F1-nolib/CDC_ACM/usb_lib.c
@@ -54,14 +54,8 @@ static const uint8_t USB_DeviceDescriptor[] = {
         bDeviceSubClass,   // bDeviceSubClass
         bDeviceProtocol,   // bDeviceProtocol
         USB_EP0_BUFSZ,   // bMaxPacketSize
-  // 0483:5740
+  // 0483:5740 (VID:PID) - stm32 VCP
     0x83, 0x04, 0x40, 0x57,
-    /*
-        0xae,   // idVendor_L VID=0x25AE, PID=0x24AB
-        0x25,   // idVendor_H
-        0xab,   // idProduct_L
-        0x24,   // idProduct_H
-*/
         0x00,   // bcdDevice_Ver_L
         0x02,   // bcdDevice_Ver_H
         0x01,   // iManufacturer
@@ -200,11 +194,10 @@ void WEAK break_handler(){
     MSG("break_handler()");
 }
 
-static uint16_t wr0(const uint8_t *buf, uint16_t size, uint16_t status){
+static void wr0(const uint8_t *buf, uint16_t size){
     if(setup_packet.wLength < size) size = setup_packet.wLength; // shortened request
     if(size < endpoints[0].txbufsz){
         EP_WriteIRQ(0, buf, size);
-        return status;
     }
     while(size){
         uint16_t l = size;
@@ -214,94 +207,86 @@ static uint16_t wr0(const uint8_t *buf, uint16_t size, uint16_t status){
         size -= l;
         uint8_t needzlp = (l == endpoints[0].txbufsz) ? 1 : 0;
         if(size || needzlp){ // send last data buffer
-            USB->ISTR = 0;
-            status = SET_VALID_TX(status);
-            status = KEEP_DTOG_TX(status);
-            status = KEEP_DTOG_RX(status);
-            status = CLEAR_CTR_RX(status);
-            status = CLEAR_CTR_TX(status);
-            USB->EPnR[0] = status;
+            uint16_t status = KEEP_DTOG(USB->EPnR[0]);
+            // keep DTOGs, clear CTR_RX,TX, set TX VALID, leave stat_Rx
+            USB->EPnR[0] = (status & ~(USB_EPnR_CTR_RX|USB_EPnR_CTR_TX|USB_EPnR_STAT_RX))
+                            ^ USB_EPnR_STAT_TX;
             uint32_t ctr = 1000000;
             while(--ctr && (USB->ISTR & USB_ISTR_CTR) == 0){IWDG->KR = IWDG_REFRESH;};
             if((USB->ISTR & USB_ISTR_CTR) == 0){
-                return USB->EPnR[0];
+                return;
             }
-            USB->ISTR = 0;
-            status = USB->EPnR[0];
             if(needzlp) EP_WriteIRQ(0, (uint8_t*)0, 0);
         }
     }
-    return status;
 }
 
-static inline uint16_t get_descriptor(uint16_t status){
+static inline void get_descriptor(){
     switch(setup_packet.wValue){
         case DEVICE_DESCRIPTOR:
-            MSG("DEVICE_D");
-            status = wr0(USB_DeviceDescriptor, sizeof(USB_DeviceDescriptor), status);
+            //MSG("DEVICE_D");
+            wr0(USB_DeviceDescriptor, sizeof(USB_DeviceDescriptor));
         break;
         case CONFIGURATION_DESCRIPTOR:
-            MSG("CONF_D");
-            status = wr0(USB_ConfigDescriptor, sizeof(USB_ConfigDescriptor), status);
+            //MSG("CONF_D");
+            wr0(USB_ConfigDescriptor, sizeof(USB_ConfigDescriptor));
         break;
         case STRING_LANG_DESCRIPTOR:
-            MSG("S_L_D");
-            status = wr0((const uint8_t *)&USB_StringLangDescriptor, STRING_LANG_DESCRIPTOR_SIZE_BYTE, status);
+            //MSG("S_L_D");
+            wr0((const uint8_t *)&USB_StringLangDescriptor, STRING_LANG_DESCRIPTOR_SIZE_BYTE);
         break;
         case STRING_MAN_DESCRIPTOR:
-            MSG("S_M_D");
-            status = wr0((const uint8_t *)&USB_StringManufacturingDescriptor, USB_StringManufacturingDescriptor.bLength, status);
+            //MSG("S_M_D");
+            wr0((const uint8_t *)&USB_StringManufacturingDescriptor, USB_StringManufacturingDescriptor.bLength);
         break;
         case STRING_PROD_DESCRIPTOR:
-            MSG("S_P_D");
-            status = wr0((const uint8_t *)&USB_StringProdDescriptor, USB_StringProdDescriptor.bLength, status);
+            //MSG("S_P_D");
+            wr0((const uint8_t *)&USB_StringProdDescriptor, USB_StringProdDescriptor.bLength);
         break;
         case STRING_SN_DESCRIPTOR:
-            MSG("S_SN_D");
-            status = wr0((const uint8_t *)&USB_StringSerialDescriptor, USB_StringSerialDescriptor.bLength, status);
+            //MSG("S_SN_D");
+            wr0((const uint8_t *)&USB_StringSerialDescriptor, USB_StringSerialDescriptor.bLength);
         break;
         case DEVICE_QUALIFIER_DESCRIPTOR:
-            MSG("D_Q_D");
-            status = wr0(USB_DeviceQualifierDescriptor, USB_DeviceQualifierDescriptor[0], status);
+            //MSG("D_Q_D");
+            wr0(USB_DeviceQualifierDescriptor, USB_DeviceQualifierDescriptor[0]);
         break;
         default:
             DBG("WTF?");
         break;
     }
-    return status;
 }
 
 static uint8_t configuration = 0; // reply for GET_CONFIGURATION (==1 if configured)
-static inline uint16_t std_d2h_req(uint16_t status){
+static inline void std_d2h_req(){
     uint16_t state = 0; // bus powered
     switch(setup_packet.bRequest){
         case GET_DESCRIPTOR:
-            status = get_descriptor(status);
+            get_descriptor();
         break;
         case GET_STATUS:
-            MSG("GET_STAT");
+            //MSG("GET_STAT");
             EP_WriteIRQ(0, (uint8_t *)&state, 2); // send status: Bus Powered
         break;
         case GET_CONFIGURATION:
-            MSG("GET_CONF");
+            //MSG("GET_CONF");
             EP_WriteIRQ(0, &configuration, 1);
         break;
         default:
             DBG("WTF?");
         break;
     }
-    return status;
 }
 
 static inline void std_h2d_req(){
     switch(setup_packet.bRequest){
         case SET_ADDRESS:
-            MSG("SET_ADDR");
+            //MSG("SET_ADDR");
             // new address will be assigned later - after  acknowlegement or request to host
             USB_Dev.USB_Addr = setup_packet.wValue;
         break;
         case SET_CONFIGURATION:
-            MSG("SET_CONF");
+            //MSG("SET_CONF");
             // Now device configured
             USB_Dev.USB_Status = USB_STATE_CONFIGURED;
             configuration = setup_packet.wValue;
@@ -323,47 +308,48 @@ bmRequestType: 76543210
  * @param ep - endpoint state
  * @return data written to EP0R
  */
-static uint16_t EP0_Handler(ep_t ep){
-    uint16_t epstatus = ep.status; // EP0R on input -> return this value after modifications
+static void EP0_Handler(){
     uint8_t reqtype = setup_packet.bmRequestType & 0x7f;
     uint8_t dev2host = (setup_packet.bmRequestType & 0x80) ? 1 : 0;
-    if ((ep.rx_flag) && (ep.setup_flag)){
+    uint16_t epstatus = USB->EPnR[0];
+    int rxflag = RX_FLAG(epstatus);
+    if(rxflag && SETUP_FLAG(epstatus)){
         switch(reqtype){
             case STANDARD_DEVICE_REQUEST_TYPE: // standard device request
+                //DBG("SDRT");
                 if(dev2host){
-                    epstatus = std_d2h_req(epstatus);
+                    std_d2h_req();
                 }else{
                     std_h2d_req();
                     EP_WriteIRQ(0, (uint8_t *)0, 0);
                 }
-//                epstatus = SET_VALID_TX(epstatus);
             break;
             case STANDARD_ENDPOINT_REQUEST_TYPE: // standard endpoint request
+                //DBG("SERT");
                 if(setup_packet.bRequest == CLEAR_FEATURE){
-                    MSG("CLEAR_F");
+                    //MSG("CLEAR_F");
                     EP_WriteIRQ(0, (uint8_t *)0, 0);
-//                    epstatus = SET_VALID_TX(epstatus);
                 }else{
                     DBG("WTF?");
                 }
             break;
             case CONTROL_REQUEST_TYPE:
+                //DBG("CRT");
                 switch(setup_packet.bRequest){
                     case GET_LINE_CODING:
-                        MSG("GET_LINE_C");
+                        //MSG("GET_LINE_C");
                         EP_WriteIRQ(0, (uint8_t*)&lineCoding, sizeof(lineCoding));
                     break;
                     case SET_LINE_CODING: // omit this for next stage, when data will come
-                        MSG("SET_LINE_C");
-                        usbON = 1;
+                        //MSG("SET_LINE_C");
                     break;
                     case SET_CONTROL_LINE_STATE:
-                        MSG("SET_CLS");
+                        //MSG("SET_CLS");
                         usbON = 1;
                         clstate_handler(setup_packet.wValue);
                     break;
                     case SEND_BREAK:
-                        MSG("SEND_BREAK");
+                        //MSG("SEND_BREAK");
                         usbON = 0;
                         break_handler();
                     break;
@@ -372,39 +358,31 @@ static uint16_t EP0_Handler(ep_t ep){
                     break;
                 }
                 if(setup_packet.bRequest != GET_LINE_CODING) EP_WriteIRQ(0, (uint8_t *)0, 0);
-//                epstatus = SET_VALID_RX(epstatus);
-//                epstatus = SET_VALID_TX(epstatus);
             break;
             default:
                 EP_WriteIRQ(0, (uint8_t *)0, 0);
                 DBG("WTF?");
-//                epstatus = SET_NAK_RX(epstatus);
-//                epstatus = SET_VALID_TX(epstatus);
         }
-    }else if (ep.rx_flag){ // got data over EP0 or host acknowlegement
-        if(ep.rx_cnt){
+    }else if(rxflag){ // got data over EP0 or host acknowlegement
+        if(endpoints[0].rx_cnt){
             if(setup_packet.bRequest == SET_LINE_CODING){
                 linecoding_handler((usb_LineCoding*)ep0databuf);
             }
         }
-        // wait for new data from host
-//        epstatus = SET_VALID_RX(epstatus);
-//        epstatus = SET_STALL_TX(epstatus);
-    } else if (ep.tx_flag){ // package transmitted
+    }else if(TX_FLAG(epstatus)){ // package transmitted
         // now we can change address after enumeration
-        if ((USB->DADDR & USB_DADDR_ADD) != USB_Dev.USB_Addr){
+        if((USB->DADDR & USB_DADDR_ADD) != USB_Dev.USB_Addr){
             USB->DADDR = USB_DADDR_EF | USB_Dev.USB_Addr;
             // change state to ADRESSED
             USB_Dev.USB_Status = USB_STATE_ADDRESSED;
-            DBG("Addressed");
+            //DBG("Addressed");
         }
-        // end of transaction
-//        epstatus = SET_VALID_RX(epstatus);
-//        epstatus = SET_VALID_TX(epstatus);
     }
-    epstatus = SET_VALID_RX(epstatus);
-    epstatus = SET_VALID_TX(epstatus);
-    return epstatus;
+    epstatus = KEEP_DTOG(USB->EPnR[0]);
+    if(rxflag) epstatus ^= USB_EPnR_STAT_TX; // start ZLP/data transmission
+    else epstatus &= ~USB_EPnR_STAT_TX; // or leave unchanged
+    // keep DTOGs, clear CTR_RX,TX, set RX VALID
+    USB->EPnR[0] = (epstatus & ~(USB_EPnR_CTR_RX|USB_EPnR_CTR_TX)) ^ USB_EPnR_STAT_RX;
 }
 
 static uint16_t lastaddr = LASTADDR_DEFAULT;
@@ -417,7 +395,7 @@ static uint16_t lastaddr = LASTADDR_DEFAULT;
  * @param uint16_t (*func)(ep_t *ep) - EP handler function
  * @return 0 if all OK
  */
-int EP_Init(uint8_t number, uint8_t type, uint16_t txsz, uint16_t rxsz, uint16_t (*func)(ep_t ep)){
+int EP_Init(uint8_t number, uint8_t type, uint16_t txsz, uint16_t rxsz, void (*func)(ep_t ep)){
     if(number >= STM32ENDPOINTS) return 4; // out of configured amount
     if(txsz > USB_BTABLE_SIZE || rxsz > USB_BTABLE_SIZE) return 1; // buffer too large
     if(lastaddr + txsz + rxsz >= USB_BTABLE_SIZE) return 2; // out of btable
@@ -446,11 +424,11 @@ int EP_Init(uint8_t number, uint8_t type, uint16_t txsz, uint16_t rxsz, uint16_t
 //extern int8_t dump;
 // standard IRQ handler
 void usb_lp_can_rx0_isr(){
-    if (USB->ISTR & USB_ISTR_RESET){
-        DBG("reset");
+    if(USB->ISTR & USB_ISTR_RESET){
+        //DBG("USB reset");
         usbON = 0;
         // Reinit registers
-        USB->CNTR = USB_CNTR_RESETM | USB_CNTR_CTRM | USB_CNTR_SUSPM;
+        USB->CNTR = USB_CNTR_RESETM | USB_CNTR_CTRM | USB_CNTR_SUSPM | USB_CNTR_WKUPM;
         // Endpoint 0 - CONTROL
         // ON USB LS size of EP0 may be 8 bytes, but on FS it should be 64 bytes!
         lastaddr = LASTADDR_DEFAULT;
@@ -458,6 +436,7 @@ void usb_lp_can_rx0_isr(){
         USB->DADDR = USB_DADDR_EF;
         // state is default - wait for enumeration
         USB_Dev.USB_Status = USB_STATE_DEFAULT;
+        USB->ISTR = ~USB_ISTR_RESET;
         if(EP_Init(0, EP_TYPE_CONTROL, USB_EP0_BUFSZ, USB_EP0_BUFSZ, EP0_Handler)){
             return;
         }
@@ -467,11 +446,6 @@ void usb_lp_can_rx0_isr(){
         uint8_t n = USB->ISTR & USB_ISTR_EPID;
         // copy status register
         uint16_t epstatus = USB->EPnR[n];
-    //  dump = 1;
-        // Calculate flags
-        endpoints[n].rx_flag = (epstatus & USB_EPnR_CTR_RX) ? 1 : 0;
-        endpoints[n].setup_flag = (epstatus & USB_EPnR_SETUP) ? 1 : 0;
-        endpoints[n].tx_flag = (epstatus & USB_EPnR_CTR_TX) ? 1 : 0;
         // copy received bytes amount
         endpoints[n].rx_cnt = USB_BTABLE->EP[n].USB_COUNT_RX & 0x3FF; // low 10 bits is counter
         // check direction
@@ -489,23 +463,20 @@ void usb_lp_can_rx0_isr(){
         }else{ // IN interrupt - transmit data, only CTR_TX == 1
             // enumeration end could be MSG (if EP0)
         }
-        // prepare status field for EP handler
-        endpoints[n].status = epstatus;
-        // call EP handler (even if it will change EPnR, it should return new status)
-        epstatus = endpoints[n].func(endpoints[n]);
-        // keep DTOG state
-        epstatus = KEEP_DTOG_TX(epstatus);
-        epstatus = KEEP_DTOG_RX(epstatus);
-        // clear all RX/TX flags
-        epstatus = CLEAR_CTR_RX(epstatus);
-        epstatus = CLEAR_CTR_TX(epstatus);
-        // refresh EPnR
-        USB->EPnR[n] = epstatus;
+        // call EP handler
+        if(endpoints[n].func) endpoints[n].func(endpoints[n]);
     }
     if(USB->ISTR & USB_ISTR_SUSP){ // suspend -> still no connection, may sleep
+        //DBG("USB suspend");
         usbON = 0;
+        USB->CNTR |= USB_CNTR_FSUSP | USB_CNTR_LP_MODE;
+        USB->ISTR = ~USB_ISTR_SUSP;
+    }
+    if(USB->ISTR & USB_ISTR_WKUP){ // wakeup
+        //DBG("USB wakeup");
+        USB->CNTR &= ~(USB_CNTR_FSUSP | USB_CNTR_LP_MODE); // clear suspend flags
+        USB->ISTR = ~USB_ISTR_WKUP;
     }
-    USB->ISTR = 0;
 }
 
 /**
@@ -534,13 +505,10 @@ void EP_WriteIRQ(uint8_t number, const uint8_t *buf, uint16_t size){
  * @param size - its size
  */
 void EP_Write(uint8_t number, const uint8_t *buf, uint16_t size){
-    uint16_t status = USB->EPnR[number];
     EP_WriteIRQ(number, buf, size);
-    //status = SET_NAK_RX(status);
-    status = SET_VALID_TX(status);
-    status = KEEP_DTOG_TX(status);
-    status = KEEP_DTOG_RX(status);
-    USB->EPnR[number] = status;
+    uint16_t status = KEEP_DTOG(USB->EPnR[number]);
+    // keep DTOGs, clear CTR_TX & set TX VALID to start transmission
+    USB->EPnR[number] = (status & ~(USB_EPnR_CTR_TX)) ^ USB_EPnR_STAT_TX;
 }
 
 /*
@@ -549,11 +517,14 @@ void EP_Write(uint8_t number, const uint8_t *buf, uint16_t size){
  * @return amount of data read
  */
 int EP_Read(uint8_t number, uint16_t *buf){
-    int n = (endpoints[number].rx_cnt + 1) >> 1;
+    int sz = endpoints[number].rx_cnt;
+    if(!sz) return 0;
+    endpoints[number].rx_cnt = 0;
+    int n = (sz + 1) >> 1;
     uint32_t *in = (uint32_t *)endpoints[number].rx_buf;
     if(n){
         for(int i = 0; i < n; ++i, ++in)
             buf[i] = *(uint16_t*)in;
     }
-    return endpoints[number].rx_cnt;
+    return sz;
 }
diff --git a/F1-nolib/CDC_ACM/usb_lib.h b/F1-nolib/CDC_ACM/usb_lib.h
index 54610a9..e4f63ba 100644
--- a/F1-nolib/CDC_ACM/usb_lib.h
+++ b/F1-nolib/CDC_ACM/usb_lib.h
@@ -78,6 +78,17 @@
 #define STRING_SN_DESCRIPTOR            0x303
 #define DEVICE_QUALIFIER_DESCRIPTOR     0x600
 
+#define RX_FLAG(epstat)                 (epstat & USB_EPnR_CTR_RX)
+#define TX_FLAG(epstat)                 (epstat & USB_EPnR_CTR_TX)
+#define SETUP_FLAG(epstat)              (epstat & USB_EPnR_SETUP)
+
+// keep all DTOGs and STATs
+#define KEEP_DTOG_STAT(EPnR)            (EPnR & ~(USB_EPnR_STAT_RX|USB_EPnR_STAT_TX|USB_EPnR_DTOG_RX|USB_EPnR_DTOG_TX))
+#define KEEP_DTOG(EPnR)                 (EPnR & ~(USB_EPnR_DTOG_RX|USB_EPnR_DTOG_TX))
+
+//#define RX_CNT(N)                       (USB_BTABLE->EP[N].USB_COUNT_RX & 0x3FF)
+
+/*
 // EPnR bits manipulation
 #define CLEAR_DTOG_RX(R)                (R & USB_EPnR_DTOG_RX) ? R : (R & (~USB_EPnR_DTOG_RX))
 #define SET_DTOG_RX(R)                  (R & USB_EPnR_DTOG_RX) ? (R & (~USB_EPnR_DTOG_RX)) : R
@@ -98,6 +109,7 @@
 #define CLEAR_CTR_RX(R)                 (R & (~USB_EPnR_CTR_RX))
 #define CLEAR_CTR_TX(R)                 (R & (~USB_EPnR_CTR_TX))
 #define CLEAR_CTR_RX_TX(R)              (R & (~(USB_EPnR_CTR_TX | USB_EPnR_CTR_RX)))
+*/
 
 // USB state: uninitialized, addressed, ready for use
 typedef enum{
@@ -151,12 +163,8 @@ typedef struct __ep_t{
     uint16_t *tx_buf;           // transmission buffer address
     uint16_t txbufsz;           // transmission buffer size
     uint16_t *rx_buf;           // reception buffer address
-    uint16_t (*func)();         // endpoint action function
-    uint16_t status;            // status flags
+    void (*func)();             // endpoint action function
     unsigned rx_cnt  : 10;      // received data counter
-    unsigned tx_flag : 1;       // transmission flag
-    unsigned rx_flag : 1;       // reception flag
-    unsigned setup_flag : 1;    // this is setup packet (only for EP0)
 } ep_t;
 
 // USB status & its address
@@ -194,7 +202,7 @@ extern uint8_t usbON;
 
 void USB_Init();
 void USB_ResetState();
-int EP_Init(uint8_t number, uint8_t type, uint16_t txsz, uint16_t rxsz, uint16_t (*func)(ep_t ep));
+int EP_Init(uint8_t number, uint8_t type, uint16_t txsz, uint16_t rxsz, void (*func)());
 void EP_WriteIRQ(uint8_t number, const uint8_t *buf, uint16_t size);
 void EP_Write(uint8_t number, const uint8_t *buf, uint16_t size);
 int EP_Read(uint8_t number, uint16_t *buf);
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