better heap info

main/ugv_main.c

@@ -160,11 +160,13 @@ void loop(void) {
   do {
     u8g2_DrawRFrame(&u8g2, 0, 0, OLED_W, OLED_H, 4);
 
-    uint32_t free_heap = xPortGetFreeHeapSize();
+    multi_heap_info_t heap_info;
+    heap_caps_get_info(&heap_info, MALLOC_CAP_DEFAULT);
     u8g2_SetFont(&u8g2, u8g2_font_4x6_mf);
     u8g2_DrawStr(&u8g2, 4, 8, "Hello World!");
-    char buf[40];
+    char buf[32];
-    snprintf(buf, 40, "free heap: %d", free_heap);
+    memset(buf, 0, 32);
+    snprintf(buf, 32, "heap allc/free %d/%d", heap_info.total_allocated_bytes, heap_info.total_free_bytes);
     u8g2_DrawStr(&u8g2, 4, 8 + 8, buf);
 
     if (packet.buffer_len) {