examples: Standardise naming of files, symbols, etc. in examples

* Use "example" in all example function & variable names, ie use i2c_example_xxx instead of i2c_xxx for example functions. Closes #198 https://github.com/espressif/esp-idf/issues/198 * Mark example functions, etc. static * Replace uses of "test" & "demo" with "example" * Split the UART example into two * Rename "main" example files to end with "_main.c" for disambiguation
2025-10-03 20:17:34 +00:00 · 2017-03-22 12:36:11 +08:00
parent 8ee6f8227e
commit 821c70f5d7
40 changed files with 624 additions and 598 deletions
--- a/examples/peripherals/i2s/main/i2s_example_main.c
+++ b/examples/peripherals/i2s/main/i2s_example_main.c
@@ -0,0 +1,69 @@
+/* I2S Example
+    
+    This example code will output 100Hz sine wave and triangle wave to 2-channel of I2S driver
+
+    This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+    Unless required by applicable law or agreed to in writing, this
+    software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+    CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include <stdio.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "driver/i2s.h"
+#include <math.h>
+
+
+#define SAMPLE_RATE     (36000)
+#define I2S_NUM         (0)
+#define WAVE_FREQ_HZ    (100)
+#define PI 3.14159265
+
+#define SAMPLE_PER_CYCLE (SAMPLE_RATE/WAVE_FREQ_HZ)
+
+void app_main()
+{
+    unsigned int i, sample_val;
+    float sin_float, triangle_float, triangle_step = 65536.0 / SAMPLE_PER_CYCLE;
+    //for 36Khz sample rates, we create 100Hz sine wave, every cycle need 36000/100 = 360 samples (4-bytes each sample)
+    //using 6 buffers, we need 60-samples per buffer
+    //2-channels, 16-bit each channel, total buffer is 360*4 = 1440 bytes
+    i2s_config_t i2s_config = {
+        .mode = I2S_MODE_MASTER | I2S_MODE_TX,                                  // Only TX
+        .sample_rate = SAMPLE_RATE,
+        .bits_per_sample = 16,                                                  //16-bit per channel
+        .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,                           //2-channels
+        .communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
+        .dma_buf_count = 6,
+        .dma_buf_len = 60,                                                      //
+        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1                                //Interrupt level 1
+    };
+    i2s_pin_config_t pin_config = {
+        .bck_io_num = 26,
+        .ws_io_num = 25,
+        .data_out_num = 22,
+        .data_in_num = -1                                                       //Not used
+    };
+
+    i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
+    i2s_set_pin(I2S_NUM, &pin_config);
+
+    triangle_float = -32767;
+
+    for(i = 0; i < SAMPLE_PER_CYCLE; i++) {
+        sin_float = sin(i * PI / 180.0);
+        if(sin_float >= 0)
+            triangle_float += triangle_step;
+        else
+            triangle_float -= triangle_step;
+        sin_float *= 32767;
+
+        sample_val = 0;
+        sample_val += (short)triangle_float;
+        sample_val = sample_val << 16;
+        sample_val += (short) sin_float;
+ 
+        i2s_push_sample(I2S_NUM, (char *)&sample_val, portMAX_DELAY);
+    }
+}