From 78c24606f5702d700d8b95f38ce4bbbe2c8ab40e Mon Sep 17 00:00:00 2001
From: Alex Voinea <voinea.dragos.alexandru@gmail.com>
Date: Wed, 24 Nov 2021 17:50:59 +0100
Subject: [PATCH] Copy the arduino CDC reset handling

---
 src/modules/usb_cdc.cpp | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/modules/usb_cdc.cpp b/src/modules/usb_cdc.cpp
index 0515b59..c8a4031 100644
--- a/src/modules/usb_cdc.cpp
+++ b/src/modules/usb_cdc.cpp
@@ -72,16 +72,19 @@ void EVENT_USB_Device_ControlRequest(void) {
  *  \param[in] CDCInterfaceInfo  Pointer to the CDC class interface configuration structure being referenced
  */
 void EVENT_CDC_Device_ControLineStateChanged(USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) {
-}
-
-void EVENT_CDC_Device_LineEncodingChanged(USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) {
-    if (CDCInterfaceInfo->State.LineEncoding.BaudRateBPS == 1200) {
-        // *(uint16_t *)0x0800U = 0x7777; //old bootloader?
-        *(uint16_t *)(RAMEND - 1) = 0x7777;
+    if (CDCInterfaceInfo->State.LineEncoding.BaudRateBPS == 1200 && !(CDCInterfaceInfo->State.ControlLineStates.HostToDevice & CDC_CONTROL_LINE_OUT_DTR)) {
+        if (pgm_read_word(FLASHEND - 1) == 0xDCFB)
+            *(uint16_t *)(RAMEND - 1) = 0x7777; //MMU2-MK3 bootloader
+        else
+            *(uint16_t *)0x0800U = 0x7777; //MMU2-MK4 bootloader with UART support
         hal::cpu::resetPending = true;
         hal::watchdog::Enable(hal::watchdog::configuration::compute(250));
     }
 }
+
+void EVENT_CDC_Device_LineEncodingChanged(USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) {
+
+}
 }
 
 namespace modules {