Chapter 2. API Reference
int dma_channel
DMA channel to be used by SPI driver (1 or 2).
Macros
SDSPI_DEFAULT_HOST
SDSPI_HOST_DEFAULT()
Default sdmmc_host_t structure initializer for SD over SPI driver.
Uses SPI mode and max frequency set to 20MHz
‘slot’should be set to an sdspi device initialized by sdspi_host_init_device().
SDSPI_SLOT_NO_CD
indicates that card detect line is not used
SDSPI_SLOT_NO_WP
indicates that write protect line is not used
SDSPI_SLOT_NO_INT
indicates that interrupt line is not used
SDSPI_DEVICE_CONFIG_DEFAULT()
Macro defining default configuration of SD SPI device.
SDSPI_SLOT_CONFIG_DEFAULT()
Macro defining default configuration of SPI host
Type Definitions
typedef int sdspi_dev_handle_t
Handle representing an SD SPI device.
2.2.15 Sigma-delta Modulation
Introduction
ESP32-S2 has a second-order sigma-delta modulation module. This driver configures the channels of the sigma-delta
module.
Functionality Overview
There are 8 independent sigma-delta modulation channels identified with sigmadelta_channel_t. Each chan-
nel is capable to output the binary, hardware generated signal with the sigma-delta modulation.
Selected channel should be set up by providing configuration parameters in sigmadelta_config_t and then
applying this configuration with sigmadelta_config().
Another option is to call individual functions, that will configure all required parameters one by one:
• Prescaler of the sigma-delta generator - sigmadelta_set_prescale()
• Duty of the output signal - sigmadelta_set_duty()
• GPIO pin to output modulated signal - sigmadelta_set_pin()
The range of the ‘duty’input parameter of sigmadelta_set_duty() is from -128 to 127 (eight bit
signed integer). If zero value is set, then the output signal’s duty will be about 50%, see description of sig-
madelta_set_duty().
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