Bootloader: Implemented jump to system memory

Inc/bootloader.h

@@ -0,0 +1,6 @@
+
+#ifndef BOOTLOADER_H
+
+void jump_to_st_usb_bootloader();
+
+#endif

Inc/config.h

@@ -25,8 +25,8 @@
 #endif
 
 #ifdef PLATFORM_CANTACT
-#define CAN_RX_BUFFER_SIZE      350
-#define CAN_TX_BUFFER_SIZE      350
+#define CAN_RX_BUFFER_SIZE      340
+#define CAN_TX_BUFFER_SIZE      340
 #endif
 
 #define CAN_TX_TIMEOUT          20

Inc/slcan.h

@@ -77,6 +77,7 @@ enum slcan_message_type {
     CANTACT_SET_MODE2 = 'M',
     CANTACT_SET_FILTER = 'F',
     CANTACT_SET_MASK = 'K',
+    CANTACT_START_BOOTLOADER = 'B',
 
     USBTIN_OPEN_LOOPBACK = 'I',
     USBTIN_OPEN_LISTEN_ONLY = 'L',

Src/bootloader.c

@@ -0,0 +1,50 @@
+
+#include <bootloader.h>
+#include <platform.h>
+#include <config.h>
+#include <led.h>
+
+
+void jump_to_st_usb_bootloader()
+{
+    // Disable interrupts
+    __disable_irq();
+
+    // Disable RCC and reset it to default values
+    RCC->CFGR = 0;
+    RCC->CR = 0x83;
+
+    //Disable systick timer and reset it to default values
+    SysTick->CTRL = 0;
+    SysTick->LOAD = 0;
+    SysTick->VAL = 0;
+
+    // Disable USB
+    USB->CNTR = USB_CNTR_PDWN;
+
+    // Disable CAN
+    CAN->MCR = CAN_MCR_SLEEP;
+
+    // Disable LEDs
+    // TODO: Surprisingly, this doesn't switch off the LED.
+//    HAL_GPIO_WritePin(LED_ACTIVITY_PORT, LED_ACTIVITY_PIN, GPIO_PIN_RESET);
+
+    // Enable interrupts
+//    __enable_irq();
+
+    __DSB();
+
+    // Re-map system memory to address 0x0
+    SYSCFG->CFGR1 = (SYSCFG->CFGR1 & ~SYSCFG_CFGR1_MEM_MODE) | SYSCFG_CFGR1_MEM_MODE_0;
+
+    // Fetch and apply bootloader's stack pointer
+    __set_MSP(*(uint32_t*)(0x00));
+
+    __DSB();
+    __ISB();
+
+    // Invoke bootloader's reset handler
+    void (*SysMemBootJump)(void);
+    SysMemBootJump = (void (*)(void)) (*((uint32_t*)(4)));
+    SysMemBootJump();
+}

Src/slcan.c

@@ -7,7 +7,8 @@
 #include "can.h"
 #include "fifo.h"
 #include "slcan.h"
-#include <error.h>
+#include "error.h"
+#include "bootloader.h"
 
 
 int8_t slcan_parse_frame(CanRxMsgTypeDef* frame, uint8_t* buf) {
@@ -184,6 +185,8 @@ int8_t slcan_parse_command(uint8_t* buf, uint8_t len) {
             return SUCCESS;
         // error
         return ERROR_TX_FIFO_OVERRUN;
+    } else if (buf[0] == CANTACT_START_BOOTLOADER) {
+        jump_to_st_usb_bootloader();
     }
 
     return ERROR_SLCAN_COMMAND_NOT_RECOGNIZED;