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spi_master

内部関数です。通常は使いません。

利用方法

#include <driver/spi_master.h>

上記宣言で利用できます。

メンバー

spi_bus_initialize()

Initialize a SPI bus

esp_err_t spi_bus_initialize(spi_host_device_t host, const spi_bus_config_t *bus_config, int dma_chan)

引数

  • spi_host_device_t host SPI peripheral that controls this bus
  • spi_bus_config_tconst * bus_config Pointer to a struct specifying how the host should be initialized
  • int dma_chan Either channel 1 or 2, or 0 in the case when no DMA is required. Selecting a DMA channel for a SPI bus allows transfers on the bus to have sizes only limited by the amount of internal memory. Selecting no DMA channel (by passing the value 0) limits the amount of bytes transfered to a maximum of 32.

戻り値

esp_err_t

spi_bus_free()

Free a SPI bus

esp_err_t spi_bus_free(spi_host_device_t host)

引数

  • spi_host_device_t host SPI peripheral to free

戻り値

esp_err_t

spi_bus_add_device()

Allocate a device on a SPI bus

This initializes the internal structures for a device, plus allocates a CS pin on the indicated SPI master peripheral and routes it to the indicated GPIO. All SPI master devices have three CS pins and can thus control up to three devices. 

esp_err_t spi_bus_add_device(spi_host_device_t host, const spi_device_interface_config_t *dev_config, spi_device_handle_t *handle)

引数

  • spi_host_device_t host SPI peripheral to allocate device on
  • spi_device_interface_config_tconst * dev_config SPI interface protocol config for the device
  • spi_device_handle_t* handle Pointer to variable to hold the device handle

戻り値

esp_err_t

spi_bus_remove_device()

Remove a device from the SPI bus

esp_err_t spi_bus_remove_device(spi_device_handle_t handle)

引数

  • spi_device_handle_t handle Device handle to free

戻り値

esp_err_t

spi_device_queue_trans()

Queue a SPI transaction for interrupt transaction execution. Get the result by .

esp_err_t spi_device_queue_trans(spi_device_handle_t handle, spi_transaction_t *trans_desc, TickType_t ticks_to_wait)

引数

  • spi_device_handle_t handle Device handle obtained using spi_host_add_dev
  • spi_transaction_t* trans_desc Description of transaction to execute
  • TickType_t ticks_to_wait Ticks to wait until there's room in the queue; use portMAX_DELAY to never time out.

戻り値

esp_err_t

spi_device_get_trans_result()

Get the result of a SPI transaction queued earlier by .

This routine will wait until a transaction to the given device succesfully completed. It will then return the description of the completed transaction so software can inspect the result and e.g. free the memory or re-use the buffers. 

esp_err_t spi_device_get_trans_result(spi_device_handle_t handle, spi_transaction_t **trans_desc, TickType_t ticks_to_wait)

引数

  • spi_device_handle_t handle Device handle obtained using spi_host_add_dev
  • spi_transaction_t** trans_desc Pointer to variable able to contain a pointer to the description of the transaction that is executed. The descriptor should not be modified until the descriptor is returned by spi_device_get_trans_result.
  • TickType_t ticks_to_wait Ticks to wait until there's a returned item; use portMAX_DELAY to never time out.

戻り値

esp_err_t

spi_device_transmit()

Send a SPI transaction, wait for it to complete, and return the result

This function is the equivalent of calling followed by . Do not use this when there is still a transaction separately queued (started) from or polling_start/transmit that hasn't been finalized. 

esp_err_t spi_device_transmit(spi_device_handle_t handle, spi_transaction_t *trans_desc)

引数

  • spi_device_handle_t handle Device handle obtained using spi_host_add_dev
  • spi_transaction_t* trans_desc Description of transaction to execute

戻り値

esp_err_t

spi_device_polling_start()

Immediately start a polling transaction.

esp_err_t spi_device_polling_start(spi_device_handle_t handle, spi_transaction_t *trans_desc, TickType_t ticks_to_wait)

引数

  • spi_device_handle_t handle Device handle obtained using spi_host_add_dev
  • spi_transaction_t* trans_desc Description of transaction to execute
  • TickType_t ticks_to_wait Ticks to wait until there's room in the queue; currently only portMAX_DELAY is supported.

戻り値

esp_err_t

spi_device_polling_end()

Poll until the polling transaction ends.

This routine will not return until the transaction to the given device has succesfully completed. The task is not blocked, but actively busy-spins for the transaction to be completed. 

esp_err_t spi_device_polling_end(spi_device_handle_t handle, TickType_t ticks_to_wait)

引数

  • spi_device_handle_t handle Device handle obtained using spi_host_add_dev
  • TickType_t ticks_to_wait Ticks to wait until there's a returned item; use portMAX_DELAY to never time out.

戻り値

esp_err_t

spi_device_polling_transmit()

Send a polling transaction, wait for it to complete, and return the result

This function is the equivalent of calling followed by . Do not use this when there is still a transaction that hasn't been finalized. 

esp_err_t spi_device_polling_transmit(spi_device_handle_t handle, spi_transaction_t *trans_desc)

引数

  • spi_device_handle_t handle Device handle obtained using spi_host_add_dev
  • spi_transaction_t* trans_desc Description of transaction to execute

戻り値

esp_err_t

spi_device_acquire_bus()

Occupy the SPI bus for a device to do continuous transactions.

Transactions to all other devices will be put off until is called. 

esp_err_t spi_device_acquire_bus(spi_device_handle_t device, TickType_t wait)

引数

  • spi_device_handle_t device The device to occupy the bus.
  • TickType_t wait Time to wait before the the bus is occupied by the device. Currently MUST set to portMAX_DELAY.

戻り値

esp_err_t

spi_device_release_bus()

Release the SPI bus occupied by the device. All other devices can start sending transactions.

void spi_device_release_bus(spi_device_handle_t dev)

引数

  • spi_device_handle_t dev The device to release the bus.

戻り値

void

spi_cal_clock()

Calculate the working frequency that is most close to desired frequency, and also the register value.

int spi_cal_clock(int fapb, int hz, int duty_cycle, uint32_t *reg_o)

引数

  • int fapb The frequency of apb clock, should be .
  • int hz Desired working frequency
  • int duty_cycle Duty cycle of the spi clock
  • uint32_t * reg_o Output of value to be set in clock register, or NULL if not needed.

戻り値

int Actual working frequency that most fit.

spi_get_timing()

Calculate the timing settings of specified frequency and settings.

void spi_get_timing(bool gpio_is_used, int input_delay_ns, int eff_clk, int *dummy_o, int *cycles_remain_o)

引数

  • bool gpio_is_used True if using GPIO matrix, or False if iomux pins are used.
  • int input_delay_ns Input delay from SCLK launch edge to MISO data valid.
  • int eff_clk Effective clock frequency (in Hz) from spi_cal_clock.
  • int * dummy_o Address of dummy bits used output. Set to NULL if not needed.
  • int * cycles_remain_o Address of cycles remaining (after dummy bits are used) output.

戻り値

void

spi_get_freq_limit()

Get the frequency limit of current configurations. SPI master working at this limit is OK, while above the limit, full duplex mode and DMA will not work, and dummy bits will be aplied in the half duplex mode.

int spi_get_freq_limit(bool gpio_is_used, int input_delay_ns)

引数

  • bool gpio_is_used True if using GPIO matrix, or False if native pins are used.
  • int input_delay_ns Input delay from SCLK launch edge to MISO data valid.

戻り値

int Frequency limit of current configurations.