serial_peripheral_interface_slave

Description

SIM_INTERFACE(serial_peripheral_interface_slave) {
        void (*spi_request)(conf_object_t *obj, int first, int last,
                            int bits, dbuffer_t *payload);
        void (*connect_master)(conf_object_t *obj, conf_object_t *master,
                               const char *port,
                               serial_peripheral_interface_flags_t flags);
        void (*disconnect_master)(conf_object_t *obj, conf_object_t *master);
};

#define SERIAL_PERIPHERAL_INTERFACE_SLAVE_INTERFACE \
        "serial_peripheral_interface_slave"

The serial_peripheral_interface_slave interface is implemented by all SPI slave devices.

The connect_master and disconnect_master functions are used to select which master device is connected. At most one master device can be connected to a slave device at once. The flags parameter to connect_master should be set according to the documentation of the serial_peripheral_interface_flags_t type.

An SPI transfer consists of a number of consecutive calls to the spi_request function. The parameters first and last represent the rise and fall of the Slave Select (SS) pin: first is true on the first spi_request call of a transfer, while last is true on the last call of a transfer.

The bits and payload parameters describe the data sent by the master device. bits defines the number of bits to send, while payload defines the data to transfer. The size of the payload buffer should be ceil(bits / 8) bytes. The first byte corresponds to the first 8 sent bits, and the least significant bit in each byte corresponds to the first sent bit. For example, the 11-bit sequence (first) 11011111101 (last) will be represented as two bytes, 0xfb followed by 0x5.

SEE ALSO

serial_peripheral_interface_master_interface_t, serial_peripheral_interface_flags_t

Execution Context

Cell Context for all methods.