*ram usage optimization

+TX FIFO increased up to 100 slots
*allow driver to wait us if we have no more room in TX FIFO buffer ( useful for huge data stream what comes without delay )

Drivers/STM32F0xx_HAL_Driver/Src/stm32f0xx_hal_can.c

@@ -1227,8 +1227,8 @@ HAL_StatusTypeDef HAL_CAN_AddTxMessage(CAN_HandleTypeDef *hcan, CAN_TxHeaderType
       (state == HAL_CAN_STATE_LISTENING))
   {
     /* Check that all the Tx mailboxes are not full */
-    if (((tsr & CAN_TSR_TME0) != 0U)   ||
-        ((tsr & CAN_TSR_TME1) != 0U)   /*||
+    if (((tsr & CAN_TSR_TME0) != 0U)  /* ||
+        ((tsr & CAN_TSR_TME1) != 0U)   ||
         ((tsr & CAN_TSR_TME2) != 0U)*/ )
     {
       /* Select an empty transmit mailbox */

Makefile

@@ -195,7 +195,10 @@ hex: $(HEX_TARGET)
 #######################################
 clean:
 	-rm -fR $(BUILD_DIR)*
-  
+
+clean_obj:
+	-rm -f $(BUILD_DIR)*/*.o $(BUILD_DIR)*/*.d $(BUILD_DIR)*/*.lst
+
 #######################################
 # dependencies
 #######################################

STM32F042C6Tx_FLASH.ld

@@ -56,7 +56,7 @@ ENTRY(Reset_Handler)
 _estack = 0x20001800;    /* end of RAM */
 /* Generate a link error if heap and stack don't fit into RAM */
 _Min_Heap_Size = 0x000;      /* required amount of heap  */
-_Min_Stack_Size = 0x400; /* required amount of stack */
+_Min_Stack_Size = 0x200; /* required amount of stack */
 
 /* Specify the memory areas */
 MEMORY

Src/pcan_can.c

@@ -5,7 +5,7 @@
 #include "pcan_can.h"
 #include "pcan_timestamp.h"
 
-#define CAN_TX_FIFO_SIZE (32)
+#define CAN_TX_FIFO_SIZE (100)
 static CAN_HandleTypeDef g_hcan = { .Instance = CAN };
 #define INTERNAL_CAN_IT_FLAGS          (  CAN_IT_TX_MAILBOX_EMPTY |\
                                           CAN_IT_RX_FIFO0_MSG_PENDING | CAN_IT_RX_FIFO1_MSG_PENDING |\
@@ -62,7 +62,7 @@ void pcan_can_init(void)
   g_hcan.Init.AutoWakeUp = DISABLE;
   g_hcan.Init.AutoRetransmission = ENABLE;
   g_hcan.Init.ReceiveFifoLocked = DISABLE;
-  g_hcan.Init.TransmitFifoPriority = DISABLE;
+  g_hcan.Init.TransmitFifoPriority = ENABLE;
 
   if( HAL_CAN_Init( &g_hcan ) != HAL_OK )
   {
@@ -173,7 +173,10 @@ static void pcan_can_flush_tx( void )
   if( pcan_try_send_message( p_msg ) < 0 )
     return;
   /* update fifo index */
-  can_dev.tx_tail = (can_dev.tx_tail+1)&(CAN_TX_FIFO_SIZE-1);
+  uint32_t tail = can_dev.tx_tail+1;
+  if( tail == CAN_TX_FIFO_SIZE )
+    tail = 0;
+  can_dev.tx_tail = tail;
 }
 
 int pcan_can_send_message( const can_message_t *p_msg )
@@ -181,16 +184,18 @@ int pcan_can_send_message( const can_message_t *p_msg )
   if( !p_msg )
     return 0;
 
-  uint32_t  tx_head_next = (can_dev.tx_head+1)&(CAN_TX_FIFO_SIZE-1);
+  uint32_t head = can_dev.tx_head+1;
+  if( head == CAN_TX_FIFO_SIZE )
+    head = 0;
   /* overflow ? just skip it */
-  if( tx_head_next == can_dev.tx_tail )
+  if( head == can_dev.tx_tail )
   {
     ++can_dev.tx_ovfs;
     return -1;
   }
 
   can_dev.tx_fifo[can_dev.tx_head] = *p_msg;
-  can_dev.tx_head = tx_head_next;
+  can_dev.tx_head = head;
 
   return 0;
 }
@@ -218,9 +223,11 @@ void pcan_can_set_bus_active( uint16_t mode )
   if( mode )
   {
     HAL_CAN_Start( &g_hcan );
+    HAL_CAN_AbortTxRequest( &g_hcan, CAN_TX_MAILBOX0 | CAN_TX_MAILBOX1 | CAN_TX_MAILBOX2 );
   }
   else
   {
+    HAL_CAN_AbortTxRequest( &g_hcan, CAN_TX_MAILBOX0 | CAN_TX_MAILBOX1 | CAN_TX_MAILBOX2 );
     HAL_CAN_Stop( &g_hcan );
   }
 }

Src/pcan_protocol.c

@@ -50,7 +50,7 @@ pcan_device =
 
 #define BLOCK_SIZE  (64)
 #define HEADER_SIZE (2)
-#define PCAN_MAX_RECORD_SIZE (BLOCK_SIZE*16)
+#define PCAN_MAX_RECORD_SIZE (BLOCK_SIZE*14)
 typedef struct
 {
   /* raw data array */
@@ -317,6 +317,7 @@ static void pcan_can_error( uint8_t err, uint8_t rx_err, uint8_t tx_err )
   }
 }
 
+#define WAIT_FOR_TXSLOTS 1
 static uint8_t pcan_decode_data_frame( uint8_t *ptr, uint16_t size, uint8_t flags  )
 {
   can_message_t msg = { 0 };
@@ -391,12 +392,31 @@ static uint8_t pcan_decode_data_frame( uint8_t *ptr, uint16_t size, uint8_t flag
 
   pcan_led_set_mode( LED_CH0_TX, LED_MODE_BLINK_FAST, 237 );
 
+#if WAIT_FOR_TXSLOTS
+  const uint16_t ts_poll = pcan_timestamp_ticks();
+  /* need more time to send data... ? */
+  while( pcan_can_send_message( &msg ) < 0 )
+  {
+    /* USB will get NACK and we will not miss other data */
+    pcan_can_poll();
+    uint16_t ts_diff = pcan_timestamp_ticks() - ts_poll;
+    /* we can't tramsit couse bus off or timeout ? */
+    if( ( pcan_device.can.err & PCAN_USB_ERROR_BUS_OFF ) ||
+        ( ts_diff >= PCAN_TICKS_FROM_US( 1000000u ) ) )
+    {
+      /* tx buffer overflow, drop all data */
+      pcan_device.can.err |= PCAN_USB_ERROR_TXFULL;
+      return size;
+    }
+  }
+#else
   if( pcan_can_send_message( &msg ) < 0 )
   {
-    /* tx queue overflow ? */
+    /* tx buffer overflow, drop all data */
     pcan_device.can.err |= PCAN_USB_ERROR_TXFULL;
     return size;
   }
+#endif
   /* return back to PC */
   if( srr_flag )
   {

Src/pcan_usb.c

@@ -321,19 +321,18 @@ static uint8_t *device_get_device_qualifier( uint16_t *length )
 
 static uint8_t *device_get_user_string( USBD_HandleTypeDef *pdev, uint8_t index, uint16_t *length )
 {
-  __ALIGN_BEGIN static uint8_t USBD_StrDesc[64] __ALIGN_END;
-
   UNUSED( pdev );
-
-  switch( index )
+  if( index == 10 )
   {
-    case 10:
-      USBD_GetString((uint8_t *)"PEAK-System Technik GmbH", USBD_StrDesc, length);
-    break;
-    default:
-      return 0;
+    __ALIGN_BEGIN static const uint16_t vendor_descriptor[1+24] __ALIGN_END = 
+    {
+      0x0332,
+      'P','E','A','K','-','S','y','s','t','e','m',' ','T','e','c','h','n','i','k',' ','G','m','b','H'
+    };
+    *length = sizeof( vendor_descriptor );
+    return (uint8_t*)vendor_descriptor;
   }
-  return USBD_StrDesc;
+  return 0;
 }
 
 USBD_ClassTypeDef usbd_pcan =

Src/usbd_desc.c

@@ -44,9 +44,6 @@ __ALIGN_BEGIN uint8_t USBD_LangIDDesc[USB_LEN_LANGID_STR_DESC] __ALIGN_END =
      HIBYTE(USBD_LANGID_STRING)
 };
 
-/* internal string descriptor */
-__ALIGN_BEGIN uint8_t USBD_StrDesc[USBD_MAX_STR_DESC_SIZ] __ALIGN_END;
-
 uint8_t * USBD_FS_DeviceDescriptor(USBD_SpeedTypeDef speed, uint16_t *length)
 {
   UNUSED(speed);
@@ -65,20 +62,22 @@ uint8_t * USBD_FS_LangIDStrDescriptor(USBD_SpeedTypeDef speed, uint16_t *length)
 uint8_t * USBD_FS_HugeStrDescriptor(USBD_SpeedTypeDef speed, uint16_t *length)
 {
   UNUSED( speed );
-
-  memset( USBD_StrDesc, 0x00, 254 );
-  *length = 252+2;
-  USBD_StrDesc[0] = ( 252 + 2 );
-  USBD_StrDesc[1] = USB_DESC_TYPE_STRING;
-  return USBD_StrDesc;
+  __ALIGN_BEGIN static const uint16_t huge_descriptor[1+126] __ALIGN_END = { 0x03FE };
+  *length = sizeof( huge_descriptor );
+  return (uint8_t*)huge_descriptor;
 }
 
 uint8_t * USBD_FS_ConfigStrDescriptor(USBD_SpeedTypeDef speed, uint16_t *length)
 {
   UNUSED(speed);
-  
-  USBD_GetString((uint8_t *)"PCAN-USB", USBD_StrDesc, length);
-  return USBD_StrDesc;
+
+  __ALIGN_BEGIN static const uint16_t cfg_descriptor[1+8] __ALIGN_END = 
+  { 
+    0x0312, 
+    'P','C','A','N','-','U','S','B' 
+  };
+  *length = sizeof( cfg_descriptor );
+  return (uint8_t*)cfg_descriptor;
 }
 
 USBD_DescriptorsTypeDef FS_Desc =