e8ac0bd429
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
5.7 KiB
C
149 lines
5.7 KiB
C
/* Wave Generator Example
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This example code is in the Public Domain (or CC0 licensed, at your option.)
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DAC output channel, waveform, wave frequency can be customized in menuconfig.
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If any questions about this example or more information is needed, please read README.md before your start.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <assert.h>
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "freertos/queue.h"
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#include "driver/gpio.h"
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#include "driver/dac.h"
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#include "driver/timer.h"
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#include "esp_log.h"
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/* The timer ISR has an execution time of 5.5 micro-seconds(us).
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Therefore, a timer period less than 5.5 us will cause trigger the interrupt watchdog.
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7 us is a safe interval that will not trigger the watchdog. No need to customize it.
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*/
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#define WITH_RELOAD 1
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#define TIMER_INTR_US 7 // Execution time of each ISR interval in micro-seconds
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#define TIMER_DIVIDER 16
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#define POINT_ARR_LEN 200 // Length of points array
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#define AMP_DAC 255 // Amplitude of DAC voltage. If it's more than 256 will causes dac_output_voltage() output 0.
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#define VDD 3300 // VDD is 3.3V, 3300mV
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#define CONST_PERIOD_2_PI 6.2832
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#define SEC_TO_MICRO_SEC(x) ((x) / 1000 / 1000) // Convert second to micro-second
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#define UNUSED_PARAM __attribute__((unused)) // A const period parameter which equals 2 * pai, used to calculate raw dac output value.
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#define TIMER_TICKS (TIMER_BASE_CLK / TIMER_DIVIDER) // TIMER_BASE_CLK = APB_CLK = 80MHz
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#define ALARM_VAL_US SEC_TO_MICRO_SEC(TIMER_INTR_US * TIMER_TICKS) // Alarm value in micro-seconds
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#define OUTPUT_POINT_NUM (int)(1000000 / (TIMER_INTR_US * FREQ) + 0.5) // The number of output wave points.
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#define DAC_CHAN CONFIG_EXAMPLE_DAC_CHANNEL // DAC_CHANNEL_1 (GPIO25) by default
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#define FREQ CONFIG_EXAMPLE_WAVE_FREQUENCY // 3kHz by default
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_Static_assert(OUTPUT_POINT_NUM <= POINT_ARR_LEN, "The CONFIG_EXAMPLE_WAVE_FREQUENCY is too low and using too long buffer.");
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static int raw_val[POINT_ARR_LEN]; // Used to store raw values
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static int volt_val[POINT_ARR_LEN]; // Used to store voltage values(in mV)
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static const char *TAG = "wave_gen";
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static int g_index = 0;
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/* Timer interrupt service routine */
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static void IRAM_ATTR timer0_ISR(void *ptr)
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{
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timer_group_clr_intr_status_in_isr(TIMER_GROUP_0, TIMER_0);
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timer_group_enable_alarm_in_isr(TIMER_GROUP_0, TIMER_0);
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int *head = (int*)ptr;
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/* DAC output ISR has an execution time of 4.4 us*/
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if (g_index >= OUTPUT_POINT_NUM) g_index = 0;
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dac_output_voltage(DAC_CHAN, *(head + g_index));
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g_index++;
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}
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/* Timer group0 TIMER_0 initialization */
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static void example_timer_init(int timer_idx, bool auto_reload)
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{
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esp_err_t ret;
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timer_config_t config = {
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.divider = TIMER_DIVIDER,
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.counter_dir = TIMER_COUNT_UP,
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.counter_en = TIMER_PAUSE,
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.alarm_en = TIMER_ALARM_EN,
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.intr_type = TIMER_INTR_LEVEL,
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.auto_reload = auto_reload,
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};
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ret = timer_init(TIMER_GROUP_0, timer_idx, &config);
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ESP_ERROR_CHECK(ret);
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ret = timer_set_counter_value(TIMER_GROUP_0, timer_idx, 0x00000000ULL);
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ESP_ERROR_CHECK(ret);
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ret = timer_set_alarm_value(TIMER_GROUP_0, timer_idx, ALARM_VAL_US);
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ESP_ERROR_CHECK(ret);
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ret = timer_enable_intr(TIMER_GROUP_0, TIMER_0);
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ESP_ERROR_CHECK(ret);
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/* Register an ISR handler */
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timer_isr_register(TIMER_GROUP_0, timer_idx, timer0_ISR, (void *)raw_val, ESP_INTR_FLAG_IRAM, NULL);
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}
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static void prepare_data(int pnt_num)
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{
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timer_pause(TIMER_GROUP_0, TIMER_0);
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for (int i = 0; i < pnt_num; i ++) {
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#ifdef CONFIG_EXAMPLE_WAVEFORM_SINE
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raw_val[i] = (int)((sin( i * CONST_PERIOD_2_PI / pnt_num) + 1) * (double)(AMP_DAC)/2 + 0.5);
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#elif CONFIG_EXAMPLE_WAVEFORM_TRIANGLE
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raw_val[i] = (i > (pnt_num/2)) ? (2 * AMP_DAC * (pnt_num - i) / pnt_num) : (2 * AMP_DAC * i / pnt_num);
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#elif CONFIG_EXAMPLE_WAVEFORM_SAWTOOTH
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raw_val[i] = (i == pnt_num) ? 0 : (i * AMP_DAC / pnt_num);
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#elif CONFIG_EXAMPLE_WAVEFORM_SQUARE
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raw_val[i] = (i < (pnt_num/2)) ? AMP_DAC : 0;
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#endif
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volt_val[i] = (int)(VDD * raw_val[i] / (float)AMP_DAC);
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}
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timer_start(TIMER_GROUP_0, TIMER_0);
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}
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static void log_info(void)
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{
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ESP_LOGI(TAG, "DAC output channel: %d", DAC_CHAN);
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if (DAC_CHAN == DAC_CHANNEL_1) {
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ESP_LOGI(TAG, "GPIO:%d", GPIO_NUM_25);
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} else {
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ESP_LOGI(TAG, "GPIO:%d", GPIO_NUM_26);
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}
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#ifdef CONFIG_EXAMPLE_WAVEFORM_SINE
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ESP_LOGI(TAG, "Waveform: SINE");
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#elif CONFIG_EXAMPLE_WAVEFORM_TRIANGLE
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ESP_LOGI(TAG, "Waveform: TRIANGLE");
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#elif CONFIG_EXAMPLE_WAVEFORM_SAWTOOTH
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ESP_LOGI(TAG, "Waveform: SAWTOOTH");
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#elif CONFIG_EXAMPLE_WAVEFORM_SQUARE
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ESP_LOGI(TAG, "Waveform: SQUARE");
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#endif
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ESP_LOGI(TAG, "Frequency(Hz): %d", FREQ);
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ESP_LOGI(TAG, "Output points num: %d\n", OUTPUT_POINT_NUM);
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}
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void app_main(void)
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{
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esp_err_t ret;
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example_timer_init(TIMER_0, WITH_RELOAD);
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ret = dac_output_enable(DAC_CHAN);
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ESP_ERROR_CHECK(ret);
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log_info();
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g_index = 0;
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prepare_data(OUTPUT_POINT_NUM);
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while(1) {
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vTaskDelay(10);
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#if CONFIG_EXAMPLE_LOG_VOLTAGE
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if (g_index < OUTPUT_POINT_NUM) {
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ESP_LOGI(TAG, "Output voltage(mV): %d", volt_val[g_index]);
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ESP_LOGD(TAG, "g_index: %d\n", g_index);
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}
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#endif
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}
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} |