This wave generator example does following: - An analog signal generator. - Offering four kinds of waveform: sine, triangle, sawtooth, square. - Customer can select their expected waveform, frequency, etc. All of them can be configured in menuconfig.
149 lines
No EOL
5.7 KiB
C
149 lines
No EOL
5.7 KiB
C
/* Wave Generator Example
|
|
|
|
This example code is in the Public Domain (or CC0 licensed, at your option.)
|
|
|
|
DAC output channel, waveform, wave frequency can be customized in menuconfig.
|
|
If any questions about this example or more information is needed, please read README.md before your start.
|
|
*/
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <math.h>
|
|
#include <assert.h>
|
|
#include "freertos/FreeRTOS.h"
|
|
#include "freertos/task.h"
|
|
#include "freertos/queue.h"
|
|
#include "driver/gpio.h"
|
|
#include "driver/dac.h"
|
|
#include "driver/timer.h"
|
|
#include "esp_log.h"
|
|
|
|
/* The timer ISR has an execution time of 5.5 micro-seconds(us).
|
|
Therefore, a timer period less than 5.5 us will cause trigger the interrupt watchdog.
|
|
7 us is a safe interval that will not trigger the watchdog. No need to customize it.
|
|
*/
|
|
|
|
#define WITH_RELOAD 1
|
|
#define TIMER_INTR_US 7 // Execution time of each ISR interval in micro-seconds
|
|
#define TIMER_DIVIDER 16
|
|
#define POINT_ARR_LEN 200 // Length of points array
|
|
#define AMP_DAC 255 // Amplitude of DAC voltage. If it's more than 256 will causes dac_output_voltage() output 0.
|
|
#define VDD 3300 // VDD is 3.3V, 3300mV
|
|
#define CONST_PERIOD_2_PI 6.2832
|
|
#define SEC_TO_MICRO_SEC(x) ((x) / 1000 / 1000) // Convert second to micro-second
|
|
#define UNUSED_PARAM __attribute__((unused)) // A const period parameter which equals 2 * pai, used to calculate raw dac output value.
|
|
#define TIMER_TICKS (TIMER_BASE_CLK / TIMER_DIVIDER) // TIMER_BASE_CLK = APB_CLK = 80MHz
|
|
#define ALARM_VAL_US SEC_TO_MICRO_SEC(TIMER_INTR_US * TIMER_TICKS) // Alarm value in micro-seconds
|
|
#define OUTPUT_POINT_NUM (int)(1000000 / (TIMER_INTR_US * FREQ) + 0.5) // The number of output wave points.
|
|
|
|
#define DAC_CHAN CONFIG_EXAMPLE_DAC_CHANNEL // DAC_CHANNEL_1 (GPIO25) by default
|
|
#define FREQ CONFIG_EXAMPLE_WAVE_FREQUENCY // 3kHz by default
|
|
|
|
_Static_assert(OUTPUT_POINT_NUM <= POINT_ARR_LEN, "The CONFIG_EXAMPLE_WAVE_FREQUENCY is too low and using too long buffer.");
|
|
|
|
static int raw_val[POINT_ARR_LEN]; // Used to store raw values
|
|
static int volt_val[POINT_ARR_LEN]; // Used to store voltage values(in mV)
|
|
static const char *TAG = "wave_gen";
|
|
|
|
static int g_index = 0;
|
|
|
|
/* Timer interrupt service routine */
|
|
static void IRAM_ATTR timer0_ISR(void *ptr)
|
|
{
|
|
timer_group_clr_intr_status_in_isr(TIMER_GROUP_0, TIMER_0);
|
|
timer_group_enable_alarm_in_isr(TIMER_GROUP_0, TIMER_0);
|
|
|
|
int *head = (int*)ptr;
|
|
|
|
/* DAC output ISR has an execution time of 4.4 us*/
|
|
if (g_index >= OUTPUT_POINT_NUM) g_index = 0;
|
|
dac_output_voltage(DAC_CHAN, *(head + g_index));
|
|
g_index++;
|
|
}
|
|
|
|
/* Timer group0 TIMER_0 initialization */
|
|
static void example_timer_init(int timer_idx, bool auto_reload)
|
|
{
|
|
esp_err_t ret;
|
|
timer_config_t config = {
|
|
.divider = TIMER_DIVIDER,
|
|
.counter_dir = TIMER_COUNT_UP,
|
|
.counter_en = TIMER_PAUSE,
|
|
.alarm_en = TIMER_ALARM_EN,
|
|
.intr_type = TIMER_INTR_LEVEL,
|
|
.auto_reload = auto_reload,
|
|
};
|
|
|
|
ret = timer_init(TIMER_GROUP_0, timer_idx, &config);
|
|
ESP_ERROR_CHECK(ret);
|
|
ret = timer_set_counter_value(TIMER_GROUP_0, timer_idx, 0x00000000ULL);
|
|
ESP_ERROR_CHECK(ret);
|
|
ret = timer_set_alarm_value(TIMER_GROUP_0, timer_idx, ALARM_VAL_US);
|
|
ESP_ERROR_CHECK(ret);
|
|
ret = timer_enable_intr(TIMER_GROUP_0, TIMER_0);
|
|
ESP_ERROR_CHECK(ret);
|
|
/* Register an ISR handler */
|
|
timer_isr_register(TIMER_GROUP_0, timer_idx, timer0_ISR, (void *)raw_val, ESP_INTR_FLAG_IRAM, NULL);
|
|
}
|
|
|
|
static void prepare_data(int pnt_num)
|
|
{
|
|
timer_pause(TIMER_GROUP_0, TIMER_0);
|
|
for (int i = 0; i < pnt_num; i ++) {
|
|
#ifdef CONFIG_EXAMPLE_WAVEFORM_SINE
|
|
raw_val[i] = (int)((sin( i * CONST_PERIOD_2_PI / pnt_num) + 1) * (double)(AMP_DAC)/2 + 0.5);
|
|
#elif CONFIG_EXAMPLE_WAVEFORM_TRIANGLE
|
|
raw_val[i] = (i > (pnt_num/2)) ? (2 * AMP_DAC * (pnt_num - i) / pnt_num) : (2 * AMP_DAC * i / pnt_num);
|
|
#elif CONFIG_EXAMPLE_WAVEFORM_SAWTOOTH
|
|
raw_val[i] = (i == pnt_num) ? 0 : (i * AMP_DAC / pnt_num);
|
|
#elif CONFIG_EXAMPLE_WAVEFORM_SQUARE
|
|
raw_val[i] = (i < (pnt_num/2)) ? AMP_DAC : 0;
|
|
#endif
|
|
volt_val[i] = (int)(VDD * raw_val[i] / (float)AMP_DAC);
|
|
}
|
|
timer_start(TIMER_GROUP_0, TIMER_0);
|
|
}
|
|
|
|
static void log_info(void)
|
|
{
|
|
ESP_LOGI(TAG, "DAC output channel: %d", DAC_CHAN);
|
|
if (DAC_CHAN == DAC_CHANNEL_1) {
|
|
ESP_LOGI(TAG, "GPIO:%d", GPIO_NUM_25);
|
|
} else {
|
|
ESP_LOGI(TAG, "GPIO:%d", GPIO_NUM_26);
|
|
}
|
|
#ifdef CONFIG_EXAMPLE_WAVEFORM_SINE
|
|
ESP_LOGI(TAG, "Waveform: SINE");
|
|
#elif CONFIG_EXAMPLE_WAVEFORM_TRIANGLE
|
|
ESP_LOGI(TAG, "Waveform: TRIANGLE");
|
|
#elif CONFIG_EXAMPLE_WAVEFORM_SAWTOOTH
|
|
ESP_LOGI(TAG, "Waveform: SAWTOOTH");
|
|
#elif CONFIG_EXAMPLE_WAVEFORM_SQUARE
|
|
ESP_LOGI(TAG, "Waveform: SQUARE");
|
|
#endif
|
|
|
|
ESP_LOGI(TAG, "Frequency(Hz): %d", FREQ);
|
|
ESP_LOGI(TAG, "Output points num: %d\n", OUTPUT_POINT_NUM);
|
|
}
|
|
|
|
void app_main(void)
|
|
{
|
|
esp_err_t ret;
|
|
example_timer_init(TIMER_0, WITH_RELOAD);
|
|
|
|
ret = dac_output_enable(DAC_CHAN);
|
|
ESP_ERROR_CHECK(ret);
|
|
|
|
log_info();
|
|
g_index = 0;
|
|
prepare_data(OUTPUT_POINT_NUM);
|
|
|
|
while(1) {
|
|
vTaskDelay(10);
|
|
#if CONFIG_EXAMPLE_LOG_VOLTAGE
|
|
if (g_index < OUTPUT_POINT_NUM) {
|
|
ESP_LOGI(TAG, "Output voltage(mV): %d", volt_val[g_index]);
|
|
ESP_LOGD(TAG, "g_index: %d\n", g_index);
|
|
}
|
|
#endif
|
|
}
|
|
} |