Add command to reset into bootloader

stm32f103t8u6/build_number.txt

@@ -1 +1 @@
-352
+353

stm32f103t8u6/src/hpgl.c

@@ -2,6 +2,7 @@
 #include "usb_cdc.h"
 #include "pwm_output.h"
 #include "led.h"
+#include "system.h"
 
 unsigned int HPGL_ParseErrorCounter = 0;
 
@@ -12,6 +13,7 @@ typedef enum
 
     // First byte of instruction has been received, waiting for second one
     HPGL_Parser_ReceivingInstruction,
+    HPGL_Parser_ReceivingDeviceControl,
 
     // Receiving the pen number (currently ignored)
     HPGL_Parser_ReceivingPenNumber,
@@ -77,6 +79,12 @@ void HPGL_Poll(void)
                 // First character of all supported instructions
                 state = HPGL_Parser_ReceivingInstruction;
             }
+            else if(character == 27)
+            {
+                // Found a device control instruction, which always starts with
+                // ESC
+                state = HPGL_Parser_ReceivingDeviceControl;
+            }
             else
             {
                 // Unsupported command
@@ -118,6 +126,25 @@ void HPGL_Poll(void)
 
                 default:
                     // Unsupported instruction
+                    HPGL_ParseErrorCounter++;
+                    state = HPGL_Parser_Error;
+                    break;
+            }
+            break;
+
+        case HPGL_Parser_ReceivingDeviceControl:
+            switch(character)
+            {
+                case 'B':
+                    // Reset into bootloader
+                    LED_On(LED_Orange);
+                    LED_On(LED_Pink);
+                    System_EnterBootloader();
+                    break;
+
+                default:
+                    // Unsupported instruction
+                    HPGL_ParseErrorCounter++;
                     state = HPGL_Parser_Error;
                     break;
             }

stm32f103t8u6/src/system.c

@@ -0,0 +1,17 @@
+#include "system.h"
+#include "usb.h"
+#include "usb_util.h"
+
+void System_EnterBootloader(void)
+{
+    USB_Disable();
+    USB_Delay(100000);
+
+    // Set bootloader magic value in RTC backup register
+    RCC->APB1ENR |= RCC_APB1ENR_BKPEN | RCC_APB1ENR_PWREN;
+    PWR->CR = PWR_CR_DBP;
+    BKP->DR1 = 0xb007;
+
+    // Initiate software reset
+    NVIC_SystemReset();
+}

stm32f103t8u6/src/system.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include "stm32f1xx.h"
+
+// Immediately reset MCU and enter bootloader
+void System_EnterBootloader(void);

stm32f103t8u6/src/usb.c

@@ -62,6 +62,21 @@ void USB_Init(void)
 
 }
 
+void USB_Disable(void)
+{
+    // Disable interrupts, force reset
+    USB->CNTR = USB_CNTR_FRES;
+
+    // Clear interrupt flags
+    USB->ISTR = 0x00;
+
+    // Power down
+    USB->CNTR = USB_CNTR_FRES | USB_CNTR_PDWN;
+
+    // Disable D- pull-up
+    GPIOA->BRR = (1 << PIN_USB_PULLUP);
+}
+
 static inline void USB_HandleReset(void)
 {
     // Remove reset flag

stm32f103t8u6/src/usb.h

@@ -134,3 +134,4 @@ typedef void (*USB_PacketHandler_t)(int length);
 extern USB_PacketHandler_t USB_EP0OutPacketHandler;
 
 void USB_Init(void);
+void USB_Disable(void);

stm32f103t8u6/src/usb_vendor.c

@@ -1,4 +1,5 @@
 #include "usb_vendor.h"
+#include "system.h"
 
 void USBVendor_HandleDeviceSetup(USB_SetupPacket_t *sp,
     const void **reply_data, int *reply_length, uint8_t *reply_response)
@@ -14,6 +15,11 @@ void USBVendor_HandleDeviceSetup(USB_SetupPacket_t *sp,
             *reply_response = USB_EP_TX_VALID;
             break;
 
+        case USB_VENDOR_COMMAND_ENTER_BOOTLOADER:
+            *reply_response = USB_EP_TX_VALID;
+            System_EnterBootloader();
+            break;
+
         default:
             *reply_response = USB_EP_TX_STALL;
     }

stm32f103t8u6/src/usb_vendor.h

@@ -5,6 +5,7 @@
 typedef enum
 {
     USB_VENDOR_COMMAND_NOP = 0x00,
+    USB_VENDOR_COMMAND_ENTER_BOOTLOADER = 0xb0,
 } USBVendor_Command_t;
 
 void USBVendor_HandleDeviceSetup(USB_SetupPacket_t *sp,