Merge branch 'espressif:master' into master

Author: Jason2866

cores/esp32/esp32-hal-ledc.c

@@ -115,6 +115,10 @@ static void _ledcSetupTimer(uint8_t chan, uint32_t div_num, uint8_t bit_num, boo
     uint8_t group=(chan/8), timer=((chan/2)%4);
     static bool tHasStarted = false;
     static uint16_t _activeChannels = 0;
+#if CONFIG_IDF_TARGET_ESP32S2
+// ESP32-S2 TRM v1.0 on Page 789 -> BIT LEDC_TICK_SEL_TIMERx is 0 for LEDC_PWM_CLK and 1 for REF_TICK
+    apb_clk = 0;        
+#endif
     if(!tHasStarted) {
         tHasStarted = true;
         periph_module_enable(PERIPH_LEDC_MODULE);

docs/source/troubleshooting.rst

@@ -1,5 +1,5 @@
 ###############
-Troubleshotting
+Troubleshooting
 ###############
 
 Common Issues
@@ -18,10 +18,36 @@ Building
 Flashing
 --------
 
-* The board is not flashing.
+Why is my board not flashing/uploading when I try to upload my sketch?
+**********************************************************************
+
+If you are trying to upload a new sketch and your board isn't responding, there are some possible reasons.
+To be able to upload the sketch via serial interface, the ESP32 must be in the download mode. The download mode allows you to upload the sketch over the serial port and to get into it, you need to keep the **GPIO0** in LOW while a resetting (**EN** pin) cycle.
+
+Possible fatal error message from the Arduino IDE:
+
+    *A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header*
+
+Here are some steps that you can try to:
+
+* Check your USB cable and try a new one.
+* Change the USB port.
+* Check your power supply.
+* In some instances, you must keep **GPIO0** LOW during the uploading process via serial interface.
+* Hold-down the **“BOOT”** button in your ESP32 board while uploading/flashing.
+
+In some development boards, you can try adding the reset delay circuit, as decribed in the *Power-on Sequence* section on the `ESP32 Hardware Design Guidelines <https://www.espressif.com/sites/default/files/documentation/esp32_hardware_design_guidelines_en.pdf>`_ in order to get into the download mode automatically.
 
 Hardware
 --------
 
-* Power Source
-* Bad USB cable or charging only cables
+Why is my computer not detecting my board?
+**************************************************
+
+If your board is not detected after connecting into the USB, you can try to:
+
+* Check if the USB driver is missing. - `USB Driver Download Link  <https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers>`_
+* Check your USB cable and try a new one.
+* Change the USB port.
+* Check your power supply.
+* Check if the board is damaged or defective.