Chapter 2. API Reference
uint32_t flags
Bitwise OR of SPI_SLAVE_HD_* flags.
uint32_t command_bits
command field bits, multiples of 8 and at least 8.
uint32_t address_bits
address field bits, multiples of 8 and at least 8.
uint32_t dummy_bits
dummy field bits, multiples of 8 and at least 8.
uint32_t queue_size
Transaction queue size. This sets how many transactions can be ‘in the air’(queued using
spi_slave_hd_queue_trans but not yet finished using spi_slave_hd_get_trans_result) at the same time.
spi_dma_chan_t dma_chan
DMA channel to used.
spi_slave_hd_callback_config_t cb_config
Callback configuration.
Macros
SPI_SLAVE_HD_TXBIT_LSBFIRST
Transmit command/address/data LSB first instead of the default MSB first.
SPI_SLAVE_HD_RXBIT_LSBFIRST
Receive data LSB first instead of the default MSB first.
SPI_SLAVE_HD_BIT_LSBFIRST
Transmit and receive LSB first.
SPI_SLAVE_HD_APPEND_MODE
Adopt DMA append mode for transactions. In this mode, users can load(append) DMA descriptors without
stopping the DMA.
Type Definitions
typedef bool (*slave_cb_t)(void *arg, spi_slave_hd_event_t *event, BaseType_t *awoken)
Callback for SPI Slave HD.
Enumerations
enum spi_slave_chan_t
Channel of SPI Slave HD to do data transaction.
Values:
SPI_SLAVE_CHAN_TX = 0
The output channel (RDDMA)
SPI_SLAVE_CHAN_RX = 1
The input channel (WRDMA)
2.2.19 Temperature Sensor
Overview
The ESP32-S2 has a built-in temperature sensor used to measure the chip’s internal temperature, and hard to
measure the environmental temperature accurately. Being built-in means that the temperature sensor should work on
any ESP32-S2 regardless of what board the chip is embedded in. The temperature sensor module contains an 8-bit
Sigma-Delta ADC and a temperature offset DAC.
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