Chapter 2. API Reference
Convert to analog signal (Optional)
Typically, if the sigma-delta signal is connected to an LED, you don’t have to add any filter between them (because
our eyes are a low pass filter naturally). However, if you want to check the real voltage or watch the analog waveform,
you need to design an analog low pass filter. Also, it is recommended to use an active filter instead of a passive filter
to gain better isolation and not lose too much voltage.
For example, you can take the following Sallen-Key topology Low Pass Filter as a reference.
Fig. 11: Sallen-Key Low Pass Filter
Application Example
Sigma-delta Modulation example: peripherals/sigmadelta.
API Reference
Header File
• components/driver/include/driver/sigmadelta.h
Functions
esp_err_t sigmadelta_config(const sigmadelta_config_t *config)
Configure Sigma-delta channel.
Return
• ESP_OK Success
• ESP_ERR_INVALID_STATE sigmadelta driver already initialized
• ESP_ERR_INVALID_ARG Parameter error
Parameters
• config: Pointer of Sigma-delta channel configuration struct
esp_err_t sigmadelta_set_duty(sigmadelta_channel_t channel, int8_t duty)
Set Sigma-delta channel duty.
Espressif Systems 362
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