adding boot counter to main.c

The boot counter is a uint8_t single-byte counter stored in the first NVM byte position (`micrcontroller.nvm[0]`). The counter increments by 1 each time the board boots, regardless if it's a hard or soft reset. 

Enable the boot counter by adding `#define CIRCUITPY_BOOT_COUNTER 1` to your board's mpconfigboard.h file. Note that an error will be thrown during the build if `CIRCUITPY_INTERNAL_NVM_SIZE` is not also set within mpconfigboard.h.

main.c

@@ -107,6 +107,10 @@
 #include "shared-bindings/wifi/__init__.h"
 #endif
 
+#ifdef CIRCUITPY_BOOT_COUNTER
+#include "shared-bindings/nvm/ByteArray.h"
+#endif
+
 #if MICROPY_ENABLE_PYSTACK
 static size_t PLACE_IN_DTCM_BSS(_pystack[CIRCUITPY_PYSTACK_SIZE / sizeof(size_t)]);
 #endif
@@ -304,6 +308,15 @@ STATIC void print_code_py_status_message(safe_mode_t safe_mode) {
     }
 }
 
+#ifdef CIRCUITPY_BOOT_COUNTER
+nvm_bytearray_obj_t bootcnt = {
+    .base = {.type = &nvm_bytearray_type},
+    .len = ( uint32_t) 1,
+    .start_address = (uint8_t*) (0x00080000 - CIRCUITPY_INTERNAL_NVM_SIZE)
+    };
+uint8_t value_out = 0;
+#endif
+
 STATIC bool run_code_py(safe_mode_t safe_mode) {
     bool serial_connected_at_start = serial_connected();
     bool printed_safe_mode_message = false;
@@ -316,6 +329,12 @@ STATIC bool run_code_py(safe_mode_t safe_mode) {
     }
     #endif
 
+    #ifdef CIRCUITPY_BOOT_COUNTER
+    common_hal_nvm_bytearray_get_bytes(&bootcnt,0,1,&value_out);
+    ++value_out;
+    common_hal_nvm_bytearray_set_bytes(&bootcnt,0,&value_out,1);
+    #endif
+
     pyexec_result_t result;
 
     result.return_code = 0;

ports/atmel-samd/boards/pycubed/mpconfigboard.h

@@ -15,6 +15,7 @@
 #define EXTERNAL_FLASH_QSPI_DUAL
 
 #define CIRCUITPY_DRIVE_LABEL "PYCUBED"
+#define CIRCUITPY_BOOT_COUNTER 1
 
 #define BOARD_HAS_CRYSTAL 1
 

ports/atmel-samd/boards/pycubed_mram/mpconfigboard.h

@@ -16,6 +16,7 @@
 #define BOARD_FLASH_SIZE (FLASH_SIZE - 0x4000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
 #define CIRCUITPY_DRIVE_LABEL "PYCUBED"
+#define CIRCUITPY_BOOT_COUNTER 1
 
 #define BOARD_HAS_CRYSTAL 1
 

py/circuitpy_mpconfig.h

@@ -554,6 +554,10 @@ void supervisor_run_background_tasks_if_tick(void);
 
 #define CIRCUITPY_BOOT_OUTPUT_FILE "/boot_out.txt"
 
+#if !defined(CIRCUITPY_INTERNAL_NVM_SIZE) && defined(CIRCUITPY_BOOT_COUNTER)
+#error "boot counter requires CIRCUITPY_NVM enabled"
+#endif
+
 #define CIRCUITPY_VERBOSE_BLE 0
 
 // This trades ~1k flash space (1) for that much in RAM plus the cost to compute