micropython · dpgeorge · Nov 22, 2023 · Nov 7, 2023 · Nov 7, 2023
diff --git a/docs/library/esp.rst b/docs/library/esp.rst
@@ -62,12 +62,35 @@ Functions
 
 .. function:: flash_erase(sector_no)
 
-.. function:: osdebug(level)
+.. function:: osdebug(uart_no)
 
-    Turn esp os debugging messages on or off.
+    .. note:: This is the ESP8266 form of this function.
 
-    The *level* parameter sets the threshold for the log messages for all esp components.
-    The log levels are defined as constants:
+    Change the level of OS serial debug log messages. On boot,
+    OS serial debug log messages are disabled.
+
+    ``uart_no`` is the number of the UART peripheral which should receive
+    OS-level output, or ``None`` to disable OS serial debug log messages.
+
+.. function:: osdebug(uart_no, [level])
+    :no-index:
+
+    .. note:: This is the ESP32 form of this function.
+
+    Change the level of OS serial debug log messages. On boot, OS
+    serial debug log messages are limited to Error output only.
+
+    The behaviour of this function depends on the arguments passed to it. The
+    following combinations are supported:
+
+    ``osdebug(None)`` restores the default OS debug log message level
+    (``LOG_ERROR``).
+
+    ``osdebug(0)`` enables all available OS debug log messages (in the
+    default build configuration this is ``LOG_INFO``).
+
+    ``osdebug(0, level)`` sets the OS debug log message level to the
+     specified value. The log levels are defined as constants:
 
         * ``LOG_NONE`` -- No log output
         * ``LOG_ERROR`` -- Critical errors, software module can not recover on its own
@@ -77,6 +100,15 @@ Functions
         * ``LOG_VERBOSE`` -- Bigger chunks of debugging information, or frequent messages
           which can potentially flood the output
 
+    .. note:: ``LOG_DEBUG`` and ``LOG_VERBOSE`` are not compiled into the
+              MicroPython binary by default, to save size. A custom build with a
+              modified "``sdkconfig``" source file is needed to see any output
+              at these log levels.
+
+    .. note:: Log output on ESP32 is automatically suspended in "Raw REPL" mode,
+              to prevent communications issues. This means OS level logging is never
+              seen when using ``mpremote run`` and similar tools.
+
 .. function:: set_native_code_location(start, length)
 
     **Note**: ESP8266 only

diff --git a/ports/esp32/boards/sdkconfig.base b/ports/esp32/boards/sdkconfig.base
@@ -17,9 +17,18 @@ CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP=y
 CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE=y
 
 # Change default log level to "ERROR" (instead of "INFO")
-CONFIG_LOG_DEFAULT_LEVEL_INFO=n
 CONFIG_LOG_DEFAULT_LEVEL_ERROR=y
-CONFIG_LOG_DEFAULT_LEVEL=1
+
+# Set the maximum included log level higher than the default,
+# so esp.osdebug() can enable more logging at runtime.
+#
+# To increase the max log verbosity to Debug or Verbose instead, comment
+# CONFIG_LOG_MAXIMUM_LEVEL_INFO=y and uncomment one of the other settings.
+#
+# If not needed, the next line can be commented entirely to save binary size.
+CONFIG_LOG_MAXIMUM_LEVEL_INFO=y
+#CONFIG_LOG_MAXIMUM_LEVEL_DEBUG=y
+#CONFIG_LOG_MAXIMUM_LEVEL_VERBOSE=y
 
 # Main XTAL Config
 # Only on: ESP32

diff --git a/ports/esp32/modesp.c b/ports/esp32/modesp.c
@@ -37,12 +37,12 @@
 #include "py/mphal.h"
 
 STATIC mp_obj_t esp_osdebug(size_t n_args, const mp_obj_t *args) {
-    esp_log_level_t level = LOG_LOCAL_LEVEL;
+    esp_log_level_t level = LOG_LOCAL_LEVEL; // Maximum available level
     if (n_args == 2) {
         level = mp_obj_get_int(args[1]);
     }
     if (args[0] == mp_const_none) {
-        // Disable logging
+        // Set logging back to boot default of ESP_LOG_ERROR
         esp_log_level_set("*", ESP_LOG_ERROR);
     } else {
         // Enable logging at the given level