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Updated sigma delta API documenation and example

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This commit is contained in:
krzychb 2017-09-25 21:20:48 +02:00
parent 2908e8a33a
commit b5e4c76bfe
4 changed files with 51 additions and 37 deletions
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19
components/driver/include/driver/sigmadelta.h
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@ -27,14 +27,14 @@ extern "C" {
* @brief Sigma-delta channel list
*/
typedef enum{
SIGMADELTA_CHANNEL_0 = 0, /*!< Sigma-delta channel0 */
SIGMADELTA_CHANNEL_1 = 1, /*!< Sigma-delta channel1 */
SIGMADELTA_CHANNEL_2 = 2, /*!< Sigma-delta channel2 */
SIGMADELTA_CHANNEL_3 = 3, /*!< Sigma-delta channel3 */
SIGMADELTA_CHANNEL_4 = 4, /*!< Sigma-delta channel4 */
SIGMADELTA_CHANNEL_5 = 5, /*!< Sigma-delta channel5 */
SIGMADELTA_CHANNEL_6 = 6, /*!< Sigma-delta channel6 */
SIGMADELTA_CHANNEL_7 = 7, /*!< Sigma-delta channel7 */
SIGMADELTA_CHANNEL_0 = 0, /*!< Sigma-delta channel 0 */
SIGMADELTA_CHANNEL_1 = 1, /*!< Sigma-delta channel 1 */
SIGMADELTA_CHANNEL_2 = 2, /*!< Sigma-delta channel 2 */
SIGMADELTA_CHANNEL_3 = 3, /*!< Sigma-delta channel 3 */
SIGMADELTA_CHANNEL_4 = 4, /*!< Sigma-delta channel 4 */
SIGMADELTA_CHANNEL_5 = 5, /*!< Sigma-delta channel 5 */
SIGMADELTA_CHANNEL_6 = 6, /*!< Sigma-delta channel 6 */
SIGMADELTA_CHANNEL_7 = 7, /*!< Sigma-delta channel 7 */
SIGMADELTA_CHANNEL_MAX,
} sigmadelta_channel_t;
@ -64,7 +64,8 @@ esp_err_t sigmadelta_config(const sigmadelta_config_t *config);
*
* This function is used to set Sigma-delta channel duty,
* If you add a capacitor between the output pin and ground,
* the average output voltage Vdc = VDDIO / 256 * duty + VDDIO/2, VDDIO is power supply voltage.
* the average output voltage will be Vdc = VDDIO / 256 * duty + VDDIO/2,
* where VDDIO is the power supply voltage.
*
* @param channel Sigma-delta channel number
* @param duty Sigma-delta duty of one channel, the value ranges from -128 to 127, recommended range is -90 ~ 90.

23
docs/api-reference/peripherals/sigmadelta.rst
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@ -1,11 +1,25 @@
Sigma-delta Modulation
======================
Overview
--------
Introduction
------------
ESP32 has a second-order sigma-delta modulation module.
This driver configures the channels of the sigma-delta module.
ESP32 has a second-order sigma-delta modulation module. This driver configures the channels of the sigma-delta module.
Functionality Overview
----------------------
There are eight independent sigma-delta modulation channels identified with :cpp:type:`sigmadelta_channel_t`. Each channel is capable to output the binary, hardware generated signal with the sigma-delta modulation.
Selected channel should be set up by providing configuration parameters in :cpp:type:`sigmadelta_config_t` and then applying this configuration with :cpp:func:`sigmadelta_config`.
Another option is to call individual functions, that will configure all required parameters one by one:
* **Prescaler** of the sigma-delta generator - :cpp:func:`sigmadelta_set_prescale`
* **Duty** of the output signal - :cpp:func:`sigmadelta_set_duty`
* **GPIO pin** to output modulated signal - :cpp:func:`sigmadelta_set_pin`
The range of the 'duty' input parameter of :cpp:func:`sigmadelta_set_duty` is from -128 to 127 (eight bit signed integer). If zero value is set, then the output signal's duty will be about 50%, see description of :cpp:func:`sigmadelta_set_duty`.
Application Example
-------------------
@ -16,4 +30,3 @@ API Reference
-------------
.. include:: /_build/inc/sigmadelta.inc

4
examples/peripherals/sigmadelta/README.md
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@ -1,7 +1,7 @@
# Example: sigma_delta modulation
This example uses the sigma_delta output modulation driver to generate modulated output on a GPIO.
This example uses the sigma-delta driver to generate modulated output on a GPIO.
By default the GPIO output is 4, however you can edit this in the `sigmadelta_init()` function inside `main/sigmadelta_test.c`.
If you connect an LED to the output GPIO, you will see it blinking slowly.
If you connect a LED to the output GPIO, you will see it blinking slowly.

42
examples/peripherals/sigmadelta/main/sigmadelta_example_main.c
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@ -11,44 +11,44 @@
#include "freertos/task.h"
#include "esp_system.h"
#include "driver/sigmadelta.h"
/*
* This test code intended to configure sigma-delta and set GPIO4 as signal output pin.
* If you connect this GPIO4 with an LED, you will see the LED blinking slowly.
* This test code will configure sigma-delta and set GPIO4 as a signal output pin.
* If you connect this GPIO4 with a LED, you will see the LED blinking slowly.
*/
/**
* @brief Sigma-delta initialization.
/*
* Configure and initialize the sigma delta modulation
* on channel 0 to output signal on GPIO4
*/
static void sigmadelta_example_init(void)
{
sigmadelta_config_t sigmadelta_cfg = {
/* Sigma-delta channel0*/
.channel = SIGMADELTA_CHANNEL_0,
/* Sigma-delta set duty 10*/
.sigmadelta_duty = 10,
/* Set prescale 30 */
.sigmadelta_prescale = 80,
/*select GPIO4 as output_io */
.sigmadelta_gpio = 4,
};
sigmadelta_config(&sigmadelta_cfg);
sigmadelta_config_t sigmadelta_cfg = {
.channel = SIGMADELTA_CHANNEL_0,
.sigmadelta_prescale = 80,
.sigmadelta_duty = 0,
.sigmadelta_gpio = 4,
};
sigmadelta_config(&sigmadelta_cfg);
}
/**
* @brief Sigma-delta test to change duty of output signal.
/*
* Perform the sigma-delta modulation test
* by changing the duty of the output signal.
*/
void app_main()
{
sigmadelta_example_init();
int8_t duty = 0;
int inc = 1;
while(1) {
while (1) {
sigmadelta_set_duty(SIGMADELTA_CHANNEL_0, duty);
/*by changing delay time, you can change the blink frequency of LED. */
/* By changing delay time, you can change the blink frequency of LED */
vTaskDelay(10 / portTICK_PERIOD_MS);
duty += inc;
if(duty == 127 || duty == -127) inc = (-1) * inc;
if (duty == 127 || duty == -127) {
inc = (-1) * inc;
}
}
}