Add the invert option for the ledc module (#3506)

components/modules/ledc.c

@@ -43,6 +43,8 @@ static int lledc_new_channel( lua_State *L )
 
   channel_config.gpio_num = opt_checkint_range(L, "gpio", -1, 0, GPIO_NUM_MAX-1);
 
+  channel_config.flags.output_invert = opt_checkbool(L, "invert", 0);
+
   lua_settop(L, top);
 
   esp_err_t timerErr = ledc_timer_config(&ledc_timer);

docs/modules/ledc.md

@@ -22,6 +22,7 @@ myChannel = ledc.newChannel({
   timer=ledc.TIMER_0 || ledc.TIMER_1 || ledc.TIMER_2 || ledc.TIMER_3,
   channel=ledc.CHANNEL_0 || ledc.CHANNEL_1 || ledc.CHANNEL_2 || ledc.CHANNEL_3 || ledc.CHANNEL_4 || ledc.CHANNEL_5 || ledc.CHANNEL_6 || ledc.CHANNEL_7,
   frequency=x,
+  invert=false,
   duty=x
 });
 ```
@@ -46,6 +47,7 @@ List of configuration tables:
     - ...
     - `ledc.CHANNEL_7`
 - `frequency` Timer frequency(Hz)
+- `invert` Inverts the output. False, with duty 0, is always low.
 - `duty` Channel duty, the duty range is [0, (2**bit_num) - 1]. Example: if ledc.TIMER_13_BIT is used maximum value is 4096 x 2 -1 = 8091
 
 #### Returns