Chapter 2. API Reference
This function is used to set Sigma-delta channel duty, If you add a capacitor between the output pin and ground,
the average output voltage will be Vdc = VDDIO / 256 * duty + VDDIO/2, where VDDIO is the power supply
voltage.
Return
• ESP_OK Success
• ESP_ERR_INVALID_STATE sigmadelta driver has not been initialized
• ESP_ERR_INVALID_ARG Parameter error
Parameters
• channel: Sigma-delta channel number
• duty: Sigma-delta duty of one channel, the value ranges from -128 to 127, recommended range is
-90 ~ 90. The waveform is more like a random one in this range.
esp_err_t sigmadelta_set_prescale(sigmadelta_channel_t channel, uint8_t prescale)
Set Sigma-delta channel’s clock pre-scale value. The source clock is APP_CLK, 80MHz. The clock frequency
of the sigma-delta channel is APP_CLK / pre_scale.
Return
• ESP_OK Success
• ESP_ERR_INVALID_STATE sigmadelta driver has not been initialized
• ESP_ERR_INVALID_ARG Parameter error
Parameters
• channel: Sigma-delta channel number
• prescale: The divider of source clock, ranges from 0 to 255
esp_err_t sigmadelta_set_pin(sigmadelta_channel_t channel, gpio_num_t gpio_num)
Set Sigma-delta signal output pin.
Return
• ESP_OK Success
• ESP_ERR_INVALID_STATE sigmadelta driver has not been initialized
• ESP_ERR_INVALID_ARG Parameter error
Parameters
• channel: Sigma-delta channel number
• gpio_num: GPIO number of output pin.
Header File
• components/hal/include/hal/sigmadelta_types.h
Structures
struct sigmadelta_config_t
Sigma-delta configure struct.
Public Members
sigmadelta_channel_t channel
Sigma-delta channel number
int8_t sigmadelta_duty
Sigma-delta duty, duty ranges from -128 to 127.
uint8_t sigmadelta_prescale
Sigma-delta prescale, prescale ranges from 0 to 255.
uint8_t sigmadelta_gpio
Sigma-delta output io number, refer to gpio.h for more details.
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