docs/esp32/quickref: Add note about different ESP32 varieties.

ricksorensen · dpgeorge · commit 595f86155aa7 · 2024-05-07T17:28:25.000+10:00
Signed-off-by: Rick Sorensen &lt;rick.sorensen@gmail.com&gt;
diff --git a/docs/esp32/quickref.rst b/docs/esp32/quickref.rst
@@ -18,6 +18,9 @@ working with this board it may be useful to get an overview of the microcontroll
    general.rst
    tutorial/index.rst
 
+Note that there are several varieties of ESP32 -- ESP32, ESP32C3, ESP32S2, ESP32S3 --
+supported by MicroPython, with some differences in functionality between them.
+
 Installing MicroPython
 ----------------------
 
@@ -58,7 +61,7 @@ The :mod:`esp32` module::
     import esp32
 
     esp32.raw_temperature() # read the internal temperature of the MCU, in Fahrenheit
-    esp32.ULP()             # access to the Ultra-Low-Power Co-processor
+    esp32.ULP()             # access to the Ultra-Low-Power Co-processor, not on ESP32C3
 
 Note that the temperature sensor in the ESP32 will typically read higher than
 ambient due to the IC getting warm while it runs.  This effect can be minimised
