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Merge branch 'doc/ledc_example_doc_improve' into 'master'

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doc(ledc): Update LEDC example README.md file

See merge request idf/esp-idf!2673
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Angus Gratton 2018-11-30 14:48:25 +08:00
parent a34a27010b ade39f823f
commit ed21457afc
2 changed files with 64 additions and 21 deletions
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81
examples/peripherals/ledc/README.md
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@ -1,30 +1,69 @@
# LEDC (LED PWM Controller) Example
# _LEDC Example_
(See the README.md file in the upper level 'examples' directory for more information about examples.)
This example shows how to control intensity of LEDs using ESP32's on-board hardware LED PWM Controller module.
## Functionality
## How to use example
Operations performed by example:
### Hardware Required
* Configuration of two timers (one high speed and the other low speed) that will be clocking four LEDC channels.
* Configuration of four channels of LEDC module, two channels will operate in high speed mode and two in low speed mode. Each channel will drive one GPIO / LED.
* Initialization of fade service to fade / gradually change intensity of LEDs.
* Operation of channels in a loop by cycling through four steps that will drive LEDs as follows:
1. Fade up / increase intensity
2. Fade down / decrease intensity (down to zero)
3. Set steady intensity
4. Set intensity to zero
## Hardware Setup
* A development board with ESP32 SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
* A USB cable for power supply and programming
Connect four LEDs to the following LEDC channels / individual GPIOs:
* Channel 0 - GPIO18
* Channel 1 - GPIO19
* Channel 2 - GPIO4
* Channel 3 - GPIO5
|ledc channel|GPIO|
|:---:|:---:|
|channel 0|GPIO18|
|channel 1|GPIO19|
|channel 2|GPIO4|
|channel 3|GPIO5|
### Configure the project
```
make menuconfig
```
* Set serial port under Serial Flasher Options.
### Build and Flash
Build the project and flash it to the board, then run monitor tool to view serial output:
```
make -j4 flash monitor
```
(To exit the serial monitor, type ``Ctrl-]``.)
See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
## Example Output
Running this example, you will see each ledc's brightness changes differently
* LEDC 1: Fade up / increase intensity
* LEDC 2: Fade down / decrease intensity
* LEDC 3: Keep a stable intensity
* LEDC 4: LED is not on
you can also see the following output log on the serial monitor:
```
1. LEDC fade up to duty = 4000
2. LEDC fade down to duty = 0
3. LEDC set duty = 4000 without fade
4. LEDC set duty = 0 without fade
...
```
## Troubleshooting
* Programming fail
* Hardware connection is not correct: run `make monitor`, and reboot your board to see if there are any output logs.
* The baud rate for downloading is too high: lower your baud rate in the `menuconfig` menu, and try again.
For any technical queries, please open an [issue] (https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you soon.

4
examples/peripherals/ledc/main/ledc_example_main.c
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@ -92,6 +92,7 @@ void app_main()
.duty = 0,
.gpio_num = LEDC_HS_CH0_GPIO,
.speed_mode = LEDC_HS_MODE,
.hpoint = 0,
.timer_sel = LEDC_HS_TIMER
},
{
@ -99,6 +100,7 @@ void app_main()
.duty = 0,
.gpio_num = LEDC_HS_CH1_GPIO,
.speed_mode = LEDC_HS_MODE,
.hpoint = 0,
.timer_sel = LEDC_HS_TIMER
},
{
@ -106,6 +108,7 @@ void app_main()
.duty = 0,
.gpio_num = LEDC_LS_CH2_GPIO,
.speed_mode = LEDC_LS_MODE,
.hpoint = 0,
.timer_sel = LEDC_LS_TIMER
},
{
@ -113,6 +116,7 @@ void app_main()
.duty = 0,
.gpio_num = LEDC_LS_CH3_GPIO,
.speed_mode = LEDC_LS_MODE,
.hpoint = 0,
.timer_sel = LEDC_LS_TIMER
},
};