Chapter 2. API Reference
int sclk_io_num
GPIO pin for SPI Clock signal, or -1 if not used.
int quadwp_io_num
GPIO pin for WP (Write Protect) signal, or -1 if not used.
int data2_io_num
GPIO pin for spi data2 signal in quad/octal mode, or -1 if not used.
int quadhd_io_num
GPIO pin for HD (Hold) signal, or -1 if not used.
int data3_io_num
GPIO pin for spi data3 signal in quad/octal mode, or -1 if not used.
int data4_io_num
GPIO pin for spi data4 signal in octal mode, or -1 if not used.
int data5_io_num
GPIO pin for spi data5 signal in octal mode, or -1 if not used.
int data6_io_num
GPIO pin for spi data6 signal in octal mode, or -1 if not used.
int data7_io_num
GPIO pin for spi data7 signal in octal mode, or -1 if not used.
int max_transfer_sz
Maximum transfer size, in bytes. Defaults to 4092 if 0 when DMA enabled, or to
SOC_SPI_MAXIMUM_BUFFER_SIZE if DMA is disabled.
uint32_t flags
Abilities of bus to be checked by the driver. Or-ed value of SPICOMMON_BUSFLAG_* flags.
int intr_flags
Interrupt flag for the bus to set the priority, and IRAM attribute, see esp_intr_alloc.h. Note that
the EDGE, INTRDISABLED attribute are ignored by the driver. Note that if ESP_INTR_FLAG_IRAM
is set, ALL the callbacks of the driver, and their callee functions, should be put in the IRAM.
Macros
SPI_MAX_DMA_LEN
SPI_SWAP_DATA_TX(DATA, LEN)
Transform unsigned integer of length <= 32 bits to the format which can be sent by the SPI driver directly.
E.g. to send 9 bits of data, you can:
uint16_t data = SPI_SWAP_DATA_TX(0x145, 9);
Then points tx_buffer to &data.
Parameters
• DATA: Data to be sent, can be uint8_t, uint16_t or uint32_t.
• LEN: Length of data to be sent, since the SPI peripheral sends from the MSB, this helps to shift the
data to the MSB.
SPI_SWAP_DATA_RX(DATA, LEN)
Transform received data of length <= 32 bits to the format of an unsigned integer.
E.g. to transform the data of 15 bits placed in a 4-byte array to integer:
uint16_t data = SPI_SWAP_DATA_RX(*(uint32_t*)t->rx_data, 15);
Parameters
• DATA: Data to be rearranged, can be uint8_t, uint16_t or uint32_t.
Espressif Systems 373
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