USB: CDC: add api to manage the DTR usage

Fixes stm32duino#1193

Signed-off-by: Frederic Pillon <[email protected]>

Author: fpistm

Diff for: cores/arduino/USBSerial.cpp

@@ -24,7 +24,8 @@
 #include "usbd_desc.h"
 #include "wiring.h"
 
-extern __IO  uint32_t lineState;
+extern __IO bool dtrState;
+extern __IO bool rtsState;
 
 USBSerial SerialUSB;
 void serialEventUSB() __attribute__((weak));
@@ -175,9 +176,14 @@ uint8_t USBSerial::numbits()
   return 8;
 }
 
+void USBSerial::dtr(bool enable)
+{
+  CDC_enableDTR(enable);
+}
+
 bool USBSerial::dtr(void)
 {
-  return false;
+  return dtrState;
 }
 
 bool USBSerial::rts(void)
@@ -187,12 +193,8 @@ bool USBSerial::rts(void)
 
 USBSerial::operator bool()
 {
-  bool result = false;
-  if (lineState == 1) {
-    result = true;
-  }
   delay(10);
-  return result;
+  return dtrState;
 }
 
 #endif // USBCON && USBD_USE_CDC

Diff for: cores/arduino/USBSerial.h

@@ -51,6 +51,8 @@ class USBSerial : public Stream {
     uint8_t stopbits();
     uint8_t paritytype();
     uint8_t numbits();
+
+    void dtr(bool enable);
     bool dtr();
     bool rts();
     enum {

Diff for: cores/arduino/stm32/usb/cdc/usbd_cdc.h

@@ -73,6 +73,10 @@ extern "C" {
 #define CDC_SET_CONTROL_LINE_STATE                  0x22U
 #define CDC_SEND_BREAK                              0x23U
 
+// Control Line State bits
+#define CLS_DTR   (1 << 0)
+#define CLS_RTS   (1 << 1)
+
 /**
   * @}
   */

Diff for: cores/arduino/stm32/usb/cdc/usbd_cdc_if.c

@@ -47,11 +47,12 @@
 USBD_HandleTypeDef hUSBD_Device_CDC;
 
 static bool CDC_initialized = false;
+static bool CDC_DTR_enabled = true;
 
 /* Received Data over USB are stored in this buffer       */
 CDC_TransmitQueue_TypeDef TransmitQueue;
 CDC_ReceiveQueue_TypeDef ReceiveQueue;
-__IO uint32_t lineState = 0;
+__IO bool dtrState = false; /* lineState */
 __IO bool receivePended = true;
 static uint32_t transmitStart = 0;
 
@@ -183,9 +184,10 @@ static int8_t USBD_CDC_Control(uint8_t cmd, uint8_t *pbuf, uint16_t length)
       break;
 
     case CDC_SET_CONTROL_LINE_STATE:
-      lineState =
-        (((USBD_SetupReqTypedef *)pbuf)->wValue & 0x01) != 0; // Check DTR state
-      if (lineState) { // Reset the transmit timeout when the port is connected
+      // Check DTR state
+      dtrState = (CDC_DTR_enabled) ? (((USBD_SetupReqTypedef *)pbuf)->wValue & CLS_DTR) : true;
+
+      if (dtrState) { // Reset the transmit timeout when the port is connected
         transmitStart = 0;
       }
 #ifdef DTR_TOGGLING_SEQ
@@ -301,7 +303,7 @@ bool CDC_connected()
   }
   return ((hUSBD_Device_CDC.dev_state == USBD_STATE_CONFIGURED)
           && (transmitTime < USB_CDC_TRANSMIT_TIMEOUT)
-          && lineState);
+          && dtrState);
 }
 
 void CDC_continue_transmit(void)
@@ -350,6 +352,12 @@ bool CDC_resume_receive(void)
   return false;
 }
 
+void CDC_enableDTR(bool enable)
+{
+  CDC_DTR_enabled = enable;
+  dtrState = true;
+}
+
 #endif /* USBD_USE_CDC */
 #endif /* USBCON */
 /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

Diff for: cores/arduino/stm32/usb/cdc/usbd_cdc_if.h

@@ -51,6 +51,7 @@ bool CDC_resume_receive(void);
 void CDC_init(void);
 void CDC_deInit(void);
 bool CDC_connected(void);
+void CDC_enableDTR(bool enable);
 
 #ifdef __cplusplus
 }