diff --git a/py/mpprint.h b/py/mpprint.h
old mode 100644
new mode 100755
index 8383ea85794c2..249d8b0b71326
--- a/py/mpprint.h
+++ b/py/mpprint.h
@@ -79,4 +79,58 @@ int mp_printf(const mp_print_t *print, const char *fmt, ...);
 int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args);
 #endif
 
+#if defined(MP_PRN_LEVEL) && (MP_PRN_LEVEL > 0)
+// Debug messages during code developing with MP_PRN(level, ...) & MP_PRN_LEVEL.
+// An approximate hierarchy of debug levels MP_PRN_LEVEL is:
+#define MP_PRN_SUPPRESS 0 // SUPPRESS all messages. Use it in the release version.
+#define MP_PRN_CRITICAL 1 // For the most CRITICAL errors, often requiring a system reset. Use a message with this level, if possible, raising an exception.
+#define MP_PRN_ERROR 2 // ERROR requiring program restart, use message with this level before raising an exception.
+#define MP_PRN_WARNING 3 // WARNING, something went wrong, but you can fix it with additional operations in code right now or may ignore it.
+#define MP_PRN_INFO 4 // INFO, it is interesting and useful for understanding a bug.
+#define MP_PRN_DEBUG 5 // DEBUG, more detailed information, dig deeper.
+#define MP_PRN_TRACE 6 // TRACE, show a flow of the algorithm, like enter/exit a function.
+// In reality, you may use your own classification of debug levels.
+
+#if defined(MP_PRN)
+#undef MP_PRN
+#endif
+
+#define MP_PRN(level, ...) \
+    do { \
+        if ((0 < level) && (level <= MP_PRN_LEVEL)) { \
+            mp_printf(MP_PYTHON_PRINTER, " MP_PRN_LEVEL=%d : ", level); \
+            mp_printf(MP_PYTHON_PRINTER, __VA_ARGS__); \
+            mp_printf(MP_PYTHON_PRINTER, " : FUNC=%s LINE=%d FILE=%s\n", __FUNCTION__, __LINE__, __FILE__); \
+        } \
+    } while (0);
+#else
+#define MP_PRN(level, ...)
+#endif
+/*
+// How to use:
+// Set MP_PRN_LEVEL in developed *.C or *.CPP file, for example
+#define MP_PRN_LEVEL 1000 // show all messages
+// Add MP_PRN() macro in code, like
+void foo(int arg) {
+    MP_PRN(MP_PRN_TRACE, "Enter foo()")
+    if (arg < 0) {
+        MP_PRN(MP_PRN_WARNING, "arg=%d less zero", arg)
+        ...
+    }
+    ...
+    int value;
+    ...
+    // calculate value
+    ...
+    MP_PRN(MP_PRN_INFO, "See a value=%d", value)
+    ...
+    MP_PRN(MP_PRN_TRACE, "Exit foo()")
+}
+
+// It is not a dogma. You may start debugging from level 3.
+#define MP_PRN_LEVEL 3
+// Then add MP_PRN(3, ...) and when gets too much messages then change some messages to the next level MP_PRN(4, ...), or MP_PRN(2, ...) etc.
+// Then you may change MP_PRN_LEVEL to 2(reduce printing), and finally to 0(supress printing).
+*/
+
 #endif // MICROPY_INCLUDED_PY_MPPRINT_H