leven: reenable usb on demand

user needs to call

  __USBStart();
  SerialUSB.begin(115200);

in the sketch.
To perform another uplaod, double click the reset button

Author: facchinm

cores/arduino/Arduino.h

@@ -117,5 +117,6 @@ float analogReference();
 #endif
 
 #include "pins_arduino.h"
+#include "usb/USB.h"
 
 #endif //__ARDUINO__H__

cores/arduino/main.cpp

@@ -1,5 +1,4 @@
 #include "Arduino.h"
-#include "usb/USB.h"
 #include "cm_backtrace/cm_backtrace.h"
 
 /* TODO: make me configurable by the variant */

cores/arduino/usb/USB.cpp

@@ -15,8 +15,6 @@
     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
-#if !defined(USE_TINYUSB) && !defined(NO_USB)
-
 #include <Arduino.h>
 #include "IRQManager.h"
 #include "USB.h"
@@ -296,6 +294,8 @@ extern "C" {
     void tud_set_irq_usbhs(IRQn_Type q);
 }
 
+__attribute__((weak)) void configure_usb_mux() {}
+
 void __USBStart() {
     USBIrqCfg_t usb_irq_cfg;
 
@@ -304,6 +304,8 @@ void __USBStart() {
         return;
     }
 
+    configure_usb_mux();
+
     /* 
      * ENABLE USB
      */
@@ -419,8 +421,4 @@ extern "C"  __attribute((weak))  void tud_msc_capacity_cb(uint8_t lun, uint32_t*
 extern "C"  __attribute((weak))  int32_t tud_msc_scsi_cb (uint8_t lun, uint8_t const scsi_cmd[16], void* buffer, uint16_t bufsize) {
 
     return -1;
-}
-
-
-
-#endif
+}

variants/SANTIAGO_COMPOSTA/variant.cpp

@@ -124,6 +124,7 @@ extern "C" const PinMuxCfg_t g_pin_cfg[] = {
   { BSP_IO_PORT_02_PIN_13,    P213   }, /* (38) D38  */
 
   { BSP_IO_PORT_05_PIN_00,    P500   }, /* (39) Analog voltage measure pin  */
+  { BSP_IO_PORT_04_PIN_08,    P408   }, /* (40) USB switch, drive high for RA4  */
 };
 
 extern "C" const size_t g_pin_cfg_size = sizeof(g_pin_cfg);
@@ -140,6 +141,19 @@ int32_t getPinIndex(bsp_io_port_pin_t p) {
   return rv;
 }
 
+#define BSP_PRV_PRCR_KEY                (0xA500U)
+#define BSP_PRV_PRCR_PRC1_UNLOCK        ((BSP_PRV_PRCR_KEY) | 0x2U)
+#define BSP_PRV_PRCR_LOCK               ((BSP_PRV_PRCR_KEY) | 0x0U)
+// if _USBStart is called, this will swap the USB port over the ESP one
+void configure_usb_mux() {
+  R_SYSTEM->PRCR = (uint16_t) BSP_PRV_PRCR_PRC1_UNLOCK;
+  (*((volatile uint32_t *) &R_SYSTEM->VBTBKR[1])) = 12;
+  R_SYSTEM->PRCR = (uint16_t) BSP_PRV_PRCR_LOCK;
+
+  pinMode(40, OUTPUT);
+  digitalWrite(40, HIGH);
+}
+
 #include "FspTimer.h"
 
 void initVariant() {