Espressif ESP32-S2 Programming Manual page 391

Chapter 2. API Reference
struct spi_transaction_ext_t
This struct is for SPI transactions which may change their address and command length. Please do set the flags
in base to SPI_TRANS_VARIABLE_CMD_ADR to use the bit length here.
Public Members
struct spi_transaction_t
Transaction data, so that pointer to
uint8_t command_bits
The command length in this transaction, in bits.
uint8_t address_bits
The address length in this transaction, in bits.
uint8_t dummy_bits
The dummy length in this transaction, in bits.
Macros
SPI_MASTER_FREQ_8M
SPI master clock is divided by 80MHz apb clock. Below defines are example frequencies, and are accurate. Be
free to specify a random frequency, it will be rounded to closest frequency (to macros below if above 8MHz).
8MHz
SPI_MASTER_FREQ_9M
8.89MHz
SPI_MASTER_FREQ_10M
10MHz
SPI_MASTER_FREQ_11M
11.43MHz
SPI_MASTER_FREQ_13M
13.33MHz
SPI_MASTER_FREQ_16M
16MHz
SPI_MASTER_FREQ_20M
20MHz
SPI_MASTER_FREQ_26M
26.67MHz
SPI_MASTER_FREQ_40M
40MHz
SPI_MASTER_FREQ_80M
80MHz
SPI_DEVICE_TXBIT_LSBFIRST
Transmit command/address/data LSB first instead of the default MSB first.
SPI_DEVICE_RXBIT_LSBFIRST
Receive data LSB first instead of the default MSB first.
SPI_DEVICE_BIT_LSBFIRST
Transmit and receive LSB first.
SPI_DEVICE_3WIRE
Use MOSI (=spid) for both sending and receiving data.
SPI_DEVICE_POSITIVE_CS
Make CS positive during a transaction instead of negative.
Espressif Systems
base
spi_transaction_t
380
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can be converted into spi_transaction_ext_t.
Release v4.4