Allow for resetting to USB bootsel via vendor-specific protocol

CMakeLists.txt

@@ -39,4 +39,8 @@ target_link_libraries(mtgcard PUBLIC
   pico_unique_id
 )
 
+target_compile_definitions(mtgcard PRIVATE
+  PICO_ENTER_USB_BOOT_ON_EXIT=1
+)
+
 pico_add_extra_outputs(mtgcard)

src/main.cpp

@@ -6,6 +6,7 @@
 
 #include <hardware/clocks.h>
 #include <pico/binary_info.h>
+#include <pico/bootrom.h>
 #include <pico/stdlib.h>
 #include <tusb.h>
 
@@ -185,6 +186,12 @@ void tud_vendor_rx_cb(uint8_t itf, const uint8_t* buffer, uint16_t bufsize)
         return;
       }
 
+      // special command to reset to bootsel
+      if (buffer[0] == 0x99)
+      {
+        rom_reset_usb_boot(0, 0);
+      }
+
       rx.state = RX::GETTING_CMC;
 
       rx.card_index = CardSlot::get_unused(flash);