接前一篇文章：ESP32-S3模组上跑通ES8388（7）
二、利用ESP-ADF操作ES8388
2. 详细解析
上一回继续解析到了ESP-ADF的audio_hal层的第1个也是最为关键的函数 —— audio_hal_init()中的第5段代码，也就是mutex_lock函数与mutex_unlock函数之间的临界区代码。再来回顾一下：
audio_hal_handle_t audio_hal_init(audio_hal_codec_config_t *audio_hal_conf, audio_hal_func_t *audio_hal_func)
{esp_err_t ret = 0;……mutex_lock(audio_hal->audio_hal_lock);ret = audio_hal->audio_codec_initialize(audio_hal_conf);if (ret == ESP_FAIL) {audio_free(audio_hal);if (audio_hal_func->handle) {return audio_hal_func->handle;} else {ESP_LOGE(TAG, "codec init failed!");return NULL;}}ret |= audio_hal->audio_codec_config_iface(audio_hal_conf->codec_mode, &audio_hal_conf->i2s_iface);if ((audio_hal_conf->codec_mode == AUDIO_HAL_CODEC_MODE_DECODE) || (audio_hal_conf->codec_mode == AUDIO_HAL_CODEC_MODE_BOTH)) {ret |= audio_hal->audio_codec_set_volume(AUDIO_HAL_VOL_DEFAULT);}AUDIO_RET_ON_FALSE(TAG, ret, return NULL, "audio_hal_init failed");audio_hal->handle = audio_hal;audio_hal_func->handle = audio_hal;mutex_unlock(audio_hal->audio_hal_lock);……
}
其中的第1段代码：
ret = audio_hal->audio_codec_initialize(audio_hal_conf);if (ret == ESP_FAIL) {audio_free(audio_hal);if (audio_hal_func->handle) {return audio_hal_func->handle;} else {ESP_LOGE(TAG, "codec init failed!");return NULL;}}实际上是调用了es8388_init函数。
上一回解析了es8388_init函数的前两段代码，本回继续往下解析。为了便于理解和回顾，再次贴出其源码，在components\audio_hal\driver\es8388\es8388.c中，如下：
/*** @return* - (-1) Error* - (0) Success*/
esp_err_t es8388_init(audio_hal_codec_config_t *cfg)
{int res = 0;
#ifdef CONFIG_ESP_LYRAT_V4_3_BOARDheadphone_detect_init(get_headphone_detect_gpio());
#endifres = i2c_init(); // ESP32 in master moderes |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL3, 0x04); // 0x04 mute/0x00 unmute&ramp;DAC unmute and disabled digital volume control soft ramp/* Chip Control and Power Management */res |= es_write_reg(ES8388_ADDR, ES8388_CONTROL2, 0x50);res |= es_write_reg(ES8388_ADDR, ES8388_CHIPPOWER, 0x00); //normal all and power up all// Disable the internal DLL to improve 8K sample rateres |= es_write_reg(ES8388_ADDR, 0x35, 0xA0);res |= es_write_reg(ES8388_ADDR, 0x37, 0xD0);res |= es_write_reg(ES8388_ADDR, 0x39, 0xD0);res |= es_write_reg(ES8388_ADDR, ES8388_MASTERMODE, cfg->i2s_iface.mode); //CODEC IN I2S SLAVE MODE/* dac */res |= es_write_reg(ES8388_ADDR, ES8388_DACPOWER, 0xC0); //disable DAC and disable Lout/Rout/1/2res |= es_write_reg(ES8388_ADDR, ES8388_CONTROL1, 0x12); //Enfr=0,Play&Record Mode,(0x17-both of mic&paly)
// res |= es_write_reg(ES8388_ADDR, ES8388_CONTROL2, 0); //LPVrefBuf=0,Pdn_ana=0res |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL1, 0x18);//1a 0x18:16bit iis , 0x00:24res |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL2, 0x02); //DACFsMode,SINGLE SPEED; DACFsRatio,256res |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL16, 0x00); // 0x00 audio on LIN1&RIN1, 0x09 LIN2&RIN2res |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL17, 0x90); // only left DAC to left mixer enable 0dbres |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL20, 0x90); // only right DAC to right mixer enable 0dbres |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL21, 0x80); // set internal ADC and DAC use the same LRCK clock, ADC LRCK as internal LRCKres |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL23, 0x00); // vroi=0res |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL24, 0x1E); // Set L1 R1 L2 R2 volume. 0x00: -30dB, 0x1E: 0dB, 0x21: 3dBres |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL25, 0x1E);res |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL26, 0);res |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL27, 0);// res |= es8388_set_adc_dac_volume(ES_MODULE_DAC, 0, 0); // 0dbint tmp = 0;if (AUDIO_HAL_DAC_OUTPUT_LINE2 == cfg->dac_output) {tmp = DAC_OUTPUT_LOUT1 | DAC_OUTPUT_ROUT1;} else if (AUDIO_HAL_DAC_OUTPUT_LINE1 == cfg->dac_output) {tmp = DAC_OUTPUT_LOUT2 | DAC_OUTPUT_ROUT2;} else {tmp = DAC_OUTPUT_LOUT1 | DAC_OUTPUT_LOUT2 | DAC_OUTPUT_ROUT1 | DAC_OUTPUT_ROUT2;}res |= es_write_reg(ES8388_ADDR, ES8388_DACPOWER, tmp); //0x3c Enable DAC and Enable Lout/Rout/1/2/* adc */res |= es_write_reg(ES8388_ADDR, ES8388_ADCPOWER, 0xFF);res |= es_write_reg(ES8388_ADDR, ES8388_ADCCONTROL1, 0xbb); // MIC Left and Right channel PGA gaintmp = 0;if (AUDIO_HAL_ADC_INPUT_LINE1 == cfg->adc_input) {tmp = ADC_INPUT_LINPUT1_RINPUT1;} else if (AUDIO_HAL_ADC_INPUT_LINE2 == cfg->adc_input) {tmp = ADC_INPUT_LINPUT2_RINPUT2;} else {tmp = ADC_INPUT_DIFFERENCE;}res |= es_write_reg(ES8388_ADDR, ES8388_ADCCONTROL2, tmp); //0x00 LINSEL & RINSEL, LIN1/RIN1 as ADC Input; DSSEL,use one DS Reg11; DSR, LINPUT1-RINPUT1res |= es_write_reg(ES8388_ADDR, ES8388_ADCCONTROL3, 0x02);res |= es_write_reg(ES8388_ADDR, ES8388_ADCCONTROL4, 0x0c); // 16 Bits length and I2S serial audio data formatres |= es_write_reg(ES8388_ADDR, ES8388_ADCCONTROL5, 0x02); //ADCFsMode,singel SPEED,RATIO=256//ALC for Microphoneres |= es8388_set_adc_dac_volume(ES_MODULE_ADC, 0, 0); // 0dbres |= es_write_reg(ES8388_ADDR, ES8388_ADCPOWER, 0x09); // Power on ADC, enable LIN&RIN, power off MICBIAS, and set int1lp to low power mode/* es8388 PA gpio_config */gpio_config_t io_conf;memset(&io_conf, 0, sizeof(io_conf));io_conf.mode = GPIO_MODE_OUTPUT;io_conf.pin_bit_mask = BIT64(get_pa_enable_gpio());io_conf.pull_down_en = 0;io_conf.pull_up_en = 0;gpio_config(&io_conf);/* enable es8388 PA */es8388_pa_power(true);codec_dac_volume_config_t vol_cfg = ES8388_DAC_VOL_CFG_DEFAULT();dac_vol_handle = audio_codec_volume_init(&vol_cfg);ESP_LOGI(ES_TAG, "init,out:%02x, in:%02x", cfg->dac_output, cfg->adc_input);return res;
}接下来是es8388_init函数的第3段代码，片段如下：
res |= es_write_reg(ES8388_ADDR, ES8388_DACCONTROL3, 0x04); // 0x04 mute/0x00 unmute&ramp;DAC unmute and disabled digital volume control soft ramp注意，由此段开始，正式进入到ES8388的相关寄存器的设置了。但在此之前，先讲一下es_write_reg函数。
es_write_reg函数在components\audio_hal\driver\es8388\es8388.c中，代码如下：
static esp_err_t es_write_reg(uint8_t slave_addr, uint8_t reg_add, uint8_t data)
{return i2c_bus_write_bytes(i2c_handle, slave_addr, ®_add, sizeof(reg_add), &data, sizeof(data));
}i2c_bus_write_bytes函数也是在components\esp_peripherals\driver\i2c_bus\i2c_bus.c中，代码如下：
esp_err_t i2c_bus_write_bytes(i2c_bus_handle_t bus, int addr, uint8_t *reg, int regLen, uint8_t *data, int datalen)
{I2C_BUS_CHECK(bus != NULL, "Handle error", ESP_FAIL);i2c_bus_t *p_bus = (i2c_bus_t *) bus;I2C_BUS_CHECK(p_bus->i2c_port < I2C_NUM_MAX, "I2C port error", ESP_FAIL);I2C_BUS_CHECK(data != NULL, "Not initialized input data pointer", ESP_FAIL);esp_err_t ret = ESP_OK;mutex_lock(p_bus->bus_lock);i2c_cmd_handle_t cmd = i2c_cmd_link_create();ret |= i2c_master_start(cmd);ret |= i2c_master_write_byte(cmd, addr, 1);ret |= i2c_master_write(cmd, reg, regLen, I2C_ACK_CHECK_EN);ret |= i2c_master_write(cmd, data, datalen, I2C_ACK_CHECK_EN);ret |= i2c_master_stop(cmd);ret |= i2c_master_cmd_begin(p_bus->i2c_port, cmd, 1000 / portTICK_RATE_MS);i2c_cmd_link_delete(cmd);mutex_unlock(p_bus->bus_lock);I2C_BUS_CHECK(ret == 0, "I2C Bus WriteReg Error", ESP_FAIL);return ret;
}这一步就是前文书提到的ESP-IDF中I2C操作流程的“3.3 运行I2C通信”。详情参见：ESP32学习笔记（17）——I2C接口使用 - 简书
本回就到这里，下一回正式开始（结合代码和手册）讲解ES8388的相关寄存器设置。