ESP32 DAC
ESP32有两个DAC通道，通道1链接GPIO25, 通道2链接GPIO26;
当DAC设置为 “built-in DAC mode”的时候，I2S可以通过DAC发送数据；
使用示例：
dac_output_enable(DAC_CHANNEL_1);
dac_output_voltage(DAC_CHANNEL_1, 200);
dac一共有8位，将3.3V电压按照255均分之后，就是dac的精度的最小单位；
API函数如下：
esp_err_tdac_pad_get_io_num(dac_channel_tchannel, gpio_num_t *gpio_num)
获取指定的DAC通道的GPIO口；
esp_err_tdac_output_voltage(dac_channel_tchannel, uint8_t dac_value)
设置DAC的输出电压；
esp_err_tdac_output_enable(dac_channel_tchannel)
DAC的输出使能；
esp_err_tdac_output_disable(dac_channel_tchannel)
DAC的输出失能；
esp_err_tdac_i2s_enable()
DAC 的I2S使能；
esp_err_tdac_i2s_disable()
DAC的I2S失能；
下面是关于量程的理解：
esp_err_tadc1_config_channel_atten(adc1_channel_tchannel, adc_atten_tatten)
该函数设定制定通道的量程范围atten;
默认量程是1.1伏特，如果想测量更高的范围的话，更改atten来更改测量量程，最高测量3.3伏特；
- Note
- 在adc1_get_raw()读值之前，确定atten的函数必须执行完毕；
- Note
- This function can be called multiple times to configure multiple ADC channels simultaneously. adc1_get_raw() can then be called for any configured channel.
- 如果想更改量程，这个函数可以多次被调用来更改量程范围；
When VDD_A is 3.3V:
0dB attenuaton (ADC_ATTEN_DB_0) gives full-scale voltage 1.1V
- 2.5dB attenuation (ADC_ATTEN_DB_2_5) gives full-scale voltage 1.5V
- 6dB attenuation (ADC_ATTEN_DB_6) gives full-scale voltage 2.2V
- 11dB attenuation (ADC_ATTEN_DB_11) gives full-scale voltage 3.9V (see note below)
Due to ADC characteristics, most accurate results are obtained within the following approximate voltage ranges:
- Note
- 最大电压对应着最大数值， (depending on ADC1 configured bit width, this value is: 4095 for 12-bits, 2047 for 11-bits, 1023 for 10-bits, 511 for 9 bits.)
- Note
- At 11dB attenuation the maximum voltage is limited by VDD_A, not the full scale voltage.
0dB attenuaton (ADC_ATTEN_DB_0) between 100 and 950mV
- 2.5dB attenuation (ADC_ATTEN_DB_2_5) between 100 and 1250mV
- 6dB attenuation (ADC_ATTEN_DB_6) between 150 to 1750mV
- 11dB attenuation (ADC_ATTEN_DB_11) between 150 to 2450mV
For maximum accuracy, use the ADC calibration APIs and measure voltages within these recommended ranges.
Return
-
- ESP_OK success
- ESP_ERR_INVALID_ARG Parameter error
- Parameters
-
channel: ADC1 channel to configureatten: Attenuation level
