Minimise build size

tutorials/stm32/nucleo-h723zg/minimal/Makefile

@@ -8,7 +8,7 @@ CFLAGS += -Wformat-truncation -fno-common -Wconversion -Wno-sign-conversion
 CFLAGS += -g3 -Os -ffunction-sections -fdata-sections
 CFLAGS += -I. -I$(MGDIR) -Icmsis_core/CMSIS/Core/Include -Icmsis_h7/Include
 CFLAGS += -mcpu=cortex-m7 -mthumb -mfloat-abi=hard -mfpu=fpv5-d16 $(CFLAGS_EXTRA)
-LDFLAGS ?= -Tlink.ld -nostdlib -nostartfiles --specs nosys.specs -lc -lgcc -Wl,--gc-sections -Wl,-Map=$@.map
+LDFLAGS ?= -Tlink.ld -nostdlib -nostartfiles --specs nano.specs -lc -lgcc -Wl,--gc-sections
 
 SOURCES = main.c hal.c
 SOURCES += cmsis_h7/Source/Templates/gcc/startup_stm32h723xx.s
@@ -28,6 +28,10 @@ firmware.signed.bin: firmware.bin
 	test -f private.pem || node $(MGDIR)/resources/sign.js keygen
 	node $(MGDIR)/resources/sign.js sign firmware.bin
 
+# Show all symbols sorted by size
+show_symbols_sorted_by_size: firmware.bin
+	arm-none-eabi-readelf -sW firmware.elf | sed 1,3d | sed 's,^.*: ,,' | tr -s ' ' | cut -d ' ' -f 2,7 | sort -nk1 | grep -v '^0 '
+
 flash: firmware.bin
 	STM32_Programmer_CLI -c port=swd -w firmware.elf -hardRst
 

tutorials/stm32/nucleo-h723zg/minimal/hal.c

@@ -3,6 +3,12 @@
 
 #include "hal.h"
 
+// Added to minimise the bin size: avoid pulling printf and friends
+void __assert_func(const char *s, int line, const char *fn, const char *expr) {
+  (void) s, (void) line, (void) fn, (void) expr;
+  for (;;) (void) 0;  // or trigger the fault handler
+}
+
 bool hal_timer_expired(volatile uint64_t *t, uint64_t period, uint64_t now) {
   uint64_t diff = now - *t;         // Wrap-safe elapsed time since last expiry
   if (period == 0) return false;    // Avoid division by zero

tutorials/stm32/nucleo-h723zg/minimal/link.ld

@@ -21,11 +21,10 @@ SECTIONS {
   _sidata = LOADADDR(.data);
 
   .bss : { _sbss = .; *(.bss SORT(.bss.*) COMMON) _ebss = .; } > ram_d1
+  _end = ALIGN(_ebss, 8);  /* Heap starts after .bss */
 
-  .eth_ram : { *(.eth_ram .eth_ram*) } > ram_d1 AT > flash
-
-  . = ALIGN(8);
-  _end = .;
+  /* Place .eth_ram into the ETH DMA accessible region */
+  .eth_ram (NOLOAD) : { *(.eth_ram .eth_ram*) } > ram_d2
 
   /* Retained health record. Startup code must neither copy nor clear it. */
   .mg_health (NOLOAD) : { KEEP(*(.mg_health .mg_health*)) } > ram_d3

tutorials/stm32/nucleo-h723zg/minimal/main.c

@@ -45,12 +45,15 @@ static void http_ev_handler(struct mg_connection *c, int ev, void *ev_data) {
     struct mg_http_message *hm = (struct mg_http_message *) ev_data;
     if (mg_match(hm->uri, mg_str("/api/tick"), NULL)) {
       mg_http_reply(c, 200, "", "{%m:%llu}\n", MG_ESC("tick"), hal_get_tick());
-    } else if (mg_match(hm->uri, mg_str("/api/kill"), NULL)) {
-      SCB->SHCSR &= ~SCB_SHCSR_USGFAULTENA_Msk;
-      __asm volatile("udf #0");
+    } else if (mg_match(hm->uri, mg_str("/api/crash"), NULL)) {
+      __asm volatile("udf #0");  // Trigger HardFault
     } else {
-      mg_http_reply(c, 200, "", "Hi from Mongoose, tick %llu\n",
-                    hal_get_tick());
+      mg_http_reply(c, 200, "",
+                    "Hi from Mongoose!\n"
+                    "tick:     %llu\n"
+                    "ram used: %zu\n"
+                    "ram free: %zu\n",
+                    hal_get_tick(), hal_ram_used(), hal_ram_free());
     }
   }
 }
@@ -67,13 +70,14 @@ int main(void) {
   hal_gpio_output(LED2);
   hal_gpio_output(LED3);
 
-  MG_INFO(("Initialised. CPU clock: %lu MHz", SystemCoreClock / 1000000));
-  MG_INFO(("Crash record: %M", mg_print_crash_record));
-
   struct mg_mgr mgr;
   mg_mgr_init(&mgr);
   mg_http_listen(&mgr, "http://0.0.0.0", http_ev_handler, NULL);
 
+  MG_INFO(("Initialised. CPU clock: %lu MHz", SystemCoreClock / 1000000));
+  MG_INFO(("RAM used: %zu, free: %zu", hal_ram_used(), hal_ram_free()));
+  MG_INFO(("Crash record: %M", mg_print_crash_record));
+
   for (;;) {
     mg_mgr_poll(&mgr, 0);
     blink_task();