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    spi_device_interface_config_t sx1276_config =  {           
                .clock_speed_hz = (SPI_SX1276_BUS_CLOCK_MHZ),   //Clock out at 10 MHz. 
                .mode=0,                                        //SPI mode 0 (CPOL=0, CPHA=0)
                .spics_io_num   = PIN_NUM_SX1276_CS,            //CS pin 
                .queue_size     = 1,                            //Transaction queue size.
                .address_bits   = 8,
                .cs_ena_pretrans = 1,                           //one clock delay prior CS line is active
                .cs_ena_posttrans= 1,                           //one clock delay after CS line is released
        };

    //Initialise the SPI bus for both devices
    spi_error_ret=spi_bus_initialize(HSPI_HOST, &spi_bus_config, NO_SPI_DMA_CHANNEL);
    ESP_ERROR_CHECK(spi_error_ret);   //SPI bus error handling

    //Attach to SPI bus
    spi_error_ret = spi_bus_add_device(HSPI_HOST, &sx1276_config, &spi_sx1276_handle);
    ESP_ERROR_CHECK(spi_error_ret);   //SPI bus error handling

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static void spi1_Send_Data_To_SX1276_Device(spi_device_handle_t spi_sx1276_handle, uint8_t addr, uint8_t *buffer, uint16_t size)
{
    static spi_transaction_t spi_transaction;
    memset(&spi_transaction, 0, sizeof(spi_transaction_t));
[Codebox=c file=Untitled.c][Codebox=c file=Untitled.c][/Codebox][/Codebox]
    spi_transaction.flags = SPI_DEVICE_HALFDUPLEX;      //SPI_TRANS_USE_TXDATA,
    spi_transaction.addr = (uint8_t) addr;
    spi_transaction.length =  8 + (size * 8);           // data length is in bits
    spi_transaction.tx_buffer = buffer;
    spi_transaction.rx_buffer = NULL;

    spi_error_ret = spi_device_queue_trans(spi_sx1276_handle, &spi_transaction, SPI_SX1276_TICKS_TIMEOUT_MS);   //queue data to send
    ESP_ERROR_CHECK(spi_error_ret);       //SPI bus error handling
}

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void spi1_Init_Spi_Bus(void)
{
    spi_device_interface_config_t spi_expander_config = {   //declaration for expander SPI device
            .clock_speed_hz = (SPI_EXPANDER_BUS_CLOCK_MHZ),  //Clock out at 10 MHz. Max. clock is 10MHz due to LoRa SX1276 transceiver limitations
            .mode=0,                                        //SPI mode 0
            .spics_io_num   = PIN_NUM_EXPANDER_CS,          //CS pin for expander
            .queue_size     = 1,                            //Transaction queue size. This sets how many transactions can be ‘in the air’ (queued using spi_device_queue_trans but not yet finished using spi_device_get_trans_result) at the same time.
            .post_cb        = spi1_Post_Transfer_Callback,   //Specify post-transfer callback to handle I/O lines
    };

    spi_device_interface_config_t sx1276_config =  {            //declaration for LoRa SX1276 transceiver
                .clock_speed_hz = (SPI_SX1276_BUS_CLOCK_MHZ),   //Clock out at 10 MHz. Max. clock is 10MHz due to LoRa SX1276 transceiver limitations
                .mode=0,                                        //SPI mode 0 (CPOL=0, CPHA=0)
                .spics_io_num   = PIN_NUM_SX1276_CS,            //CS pin for LoRa SX1276 transceiver
                .queue_size     = 1,                            //Transaction queue size. This sets how many transactions can be ‘in the air’ (queued using spi_device_queue_trans but not yet finished using spi_device_get_trans_result) at the same time.
                .command_bits   = 0,
                .address_bits   = 8,
                //.cs_ena_pretrans = 1,                           //one clock delay prior CS line is active
                //.cs_ena_posttrans= 1,                           //one clock delay after CS line is released
                .dummy_bits     = 0,                          //added dummy bits
                //.post_cb        = spi1_Post_Transfer_Callback,   //Specify post-transfer callback to handle I/O lines
        };

    //Initialise the SPI bus for both devices
    spi_error_ret=spi_bus_initialize(HSPI_HOST, &spi_bus_config, NO_SPI_DMA_CHANNEL);
    ESP_ERROR_CHECK(spi_error_ret);   //SPI bus error handling

    //Attach the expander device to the SPI bus
    spi_error_ret = spi_bus_add_device(HSPI_HOST, &spi_expander_config, &spi_expander_handle);
    ESP_ERROR_CHECK(spi_error_ret);   //SPI bus error handling

    //Attach the SX1276 tranceiver chip to SPI bus
    spi_error_ret = spi_bus_add_device(HSPI_HOST, &sx1276_config, &spi_sx1276_handle);
    ESP_ERROR_CHECK(spi_error_ret);   //SPI bus error handling
}

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static void spi1_Send_Data_To_SX1276_Device(spi_device_handle_t spi_sx1276_handle, uint8_t addr, uint8_t *buffer, uint16_t size)
{
    spi_transaction_ext_t spi_transaction = (spi_transaction_ext_t) {           //extended transaction is required because of different address length
        .base = {
                .flags = ( SPI_TRANS_VARIABLE_ADDR | SPI_TRANS_VARIABLE_CMD ),  //define various address and command length
                .addr = (uint8_t) addr,                                         //set address
                .length = size * 8,                                             //data length
                .tx_buffer = buffer,                                            //pointer to TX buffer
                .rx_buffer = NULL,                                              //no RX buffer
        },
        .command_bits = 0,                                                      //zero command bits
        .address_bits = 8,                                                      //eight address bits
        .dummy_bits = 0,                                                        //zero dummy bits
    };

    spi_error_ret = spi_device_queue_trans(spi_sx1276_handle, (spi_transaction_t*)&spi_transaction, SPI_SX1276_TICKS_TIMEOUT_MS);   //queue data to send
    ESP_ERROR_CHECK(spi_error_ret);       //SPI bus error handling
}