Minor tweaks in STM32 examples

Fix comments in newer mip initialization (main.c) Correct stack initialization (boot.c) Remove SCC clock enable when not needed (mcu.h)

Author: scaprile

examples/stm32/nucleo-f429zi-baremetal/boot.c

@@ -3,9 +3,6 @@
 
 // Startup code
 __attribute__((naked, noreturn)) void _reset(void) {
- // Init stack
- asm("ldr sp, = _estack");
-
  // Initialise memory
  extern long _sbss, _ebss, _sdata, _edata, _sidata;
  for (long *src = &_sbss; src < &_ebss; src++) *src = 0;
@@ -125,9 +122,10 @@ WEAK_ALIAS void LTDC_ER_IRQHandler(void);
 WEAK_ALIAS void DMA2D_IRQHandler(void);
 
 // IRQ table
+extern void _estack();
 __attribute__((section(".vectors"))) void (*tab[16 + 91])(void) = {
  // Cortex interrupts
- 0, _reset, NMI_Handler, HardFault_Handler, MemManage_Handler,
+ _estack, _reset, NMI_Handler, HardFault_Handler, MemManage_Handler,
  BusFault_Handler, UsageFault_Handler, 0, 0, 0, 0, SVC_Handler,
  DebugMon_Handler, 0, PendSV_Handler, SysTick_Handler,
 

examples/stm32/nucleo-f429zi-baremetal/main.c

@@ -68,7 +68,7 @@ int main(void) {
  mg_timer_add(&mgr, 500, MG_TIMER_REPEAT, blink_cb, &mgr);
 
  // Initialise Mongoose network stack
- // Specify MAC address, and use 0 for IP, mask, GW - i.e. use DHCP
+ // Specify MAC address, either set use_dhcp or enter a static config.
  // For static configuration, specify IP/mask/GW in network byte order
  struct mip_driver_stm32 driver_data = {.mdc_cr = 4}; // See driver_stm32.h
  struct mip_if mif = {

examples/stm32/nucleo-f429zi-baremetal/mcu.h

@@ -65,7 +65,6 @@ static inline void systick_init(uint32_t ticks) {
  SYSTICK->LOAD = ticks - 1;
  SYSTICK->VAL = 0;
  SYSTICK->CTRL = BIT(0) | BIT(1) | BIT(2); // Enable systick
- RCC->APB2ENR |= BIT(14); // Enable SYSCFG
 }
 
 struct flash {

examples/stm32/nucleo-f429zi-freertos-mip/main.c

@@ -31,6 +31,7 @@ static void ethernet_init(void) {
  }
 
  NVIC_EnableIRQ(61); // Setup Ethernet IRQ handler
+ RCC->APB2ENR |= BIT(14); // Enable SYSCFG
  SYSCFG->PMC |= BIT(23); // Use RMII. Goes first!
  RCC->AHB1ENR |= BIT(25) | BIT(26) | BIT(27); // Enable Ethernet clocks
  RCC->AHB1RSTR |= BIT(25); // ETHMAC force reset
@@ -43,7 +44,7 @@ static void server(void *args) {
  mg_log_set(MG_LL_DEBUG); // Set log level
 
  // Initialise Mongoose network stack
- // Specify MAC address, and use 0 for IP, mask, GW - i.e. use DHCP
+ // Specify MAC address, either set use_dhcp or enter a static config.
  // For static configuration, specify IP/mask/GW in network byte order
  MG_INFO(("Initializing Ethernet driver"));
  ethernet_init();
@@ -74,7 +75,6 @@ static void blinker(void *args) {
 }
 
 int main(void) {
- RCC->APB2ENR |= BIT(14); // Enable SYSCFG: for systick & Ethernet
  clock_init(); // Set clock to max of 180 MHz
  systick_init(FREQ / 1000); // Tick every 1 ms
  uart_init(UART3, 115200); // Initialise UART

examples/stm32/nucleo-f746zg-baremetal/boot.c

@@ -3,9 +3,6 @@
 
 // Startup code
 __attribute__((naked, noreturn)) void _reset(void) {
- // Init stack
- asm("ldr sp, = _estack");
-
  // Initialise memory
  extern long _sbss, _ebss, _sdata, _edata, _sidata;
  for (long *src = &_sbss; src < &_ebss; src++) *src = 0;
@@ -132,9 +129,10 @@ WEAK_ALIAS void I2C4_ER_IRQHandler(void);
 WEAK_ALIAS void SPDIF_RX_IRQHandler(void);
 
 // IRQ table
+extern void _estack();
 __attribute__((section(".vectors"))) void (*tab[16 + 98])(void) = {
  // Cortex interrupts
- 0, _reset, NMI_Handler, HardFault_Handler, MemManage_Handler,
+ _estack, _reset, NMI_Handler, HardFault_Handler, MemManage_Handler,
  BusFault_Handler, UsageFault_Handler, 0, 0, 0, 0, SVC_Handler,
  DebugMon_Handler, 0, PendSV_Handler, SysTick_Handler,
 

examples/stm32/nucleo-f746zg-baremetal/main.c

@@ -68,7 +68,7 @@ int main(void) {
  mg_timer_add(&mgr, 500, MG_TIMER_REPEAT, blink_cb, &mgr);
 
  // Initialise Mongoose network stack
- // Specify MAC address, and use 0 for IP, mask, GW - i.e. use DHCP
+ // Specify MAC address, either set use_dhcp or enter a static config.
  // For static configuration, specify IP/mask/GW in network byte order
  struct mip_driver_stm32 driver_data = {.mdc_cr = 4}; // See driver_stm32.h
  struct mip_if mif = {

examples/stm32/nucleo-f746zg-baremetal/mcu.h

@@ -66,7 +66,6 @@ static inline void systick_init(uint32_t ticks) {
  SYSTICK->LOAD = ticks - 1;
  SYSTICK->VAL = 0;
  SYSTICK->CTRL = BIT(0) | BIT(1) | BIT(2); // Enable systick
- RCC->APB2ENR |= BIT(14); // Enable SYSCFG
 }
 
 struct flash {