SPI Master spi_transaction_t

[arunbm123]

hi friends

Please can any one explain memebers of struct spi_transaction_t

uint16_t cmd
uint64_t addr


I know they are command and address...but address of what ? is it address of peripheral ??

Kindly explain
Thanks

[ESP_Sprite]

'Command' and 'address' are just fields that are sent out in the same fashion as the data; the fact that they are separate is a remnant of the fact that the SPI peripherals are also designed to drive SPI flash, which has these conventions. We left support for it in the driver as there are other SPI devices where this also can come in handy.

[arunbm123]

ok

hi,
I am using SPI to Send data to MAX7219 LED MATRIX

I am not understanding whats going wrong...kindly help

Code: Select all

void app_main()
{

	esp_err_t ret;

    spi_bus_config_t busconfig={
        .miso_io_num=PIN_NUM_MISO,
        .mosi_io_num=PIN_NUM_MOSI,
        .sclk_io_num=PIN_NUM_CLK,
        .quadwp_io_num=-1,
        .quadhd_io_num=-1,
        .max_transfer_sz=PARALLEL_LINES*320*1+8
    };

    spi_device_interface_config_t dev_config={
		 .address_bits = 0,
		 .command_bits = 0,
		 .dummy_bits = 0,
		 .mode = 0,
		 .duty_cycle_pos = 0,
		 .cs_ena_posttrans = 0,
		 .cs_ena_pretrans = 0,
		 .clock_speed_hz = 10000,
		 .spics_io_num = PIN_NUM_CS,
		 .flags = 0,
		 .queue_size = 1,
		 .pre_cb = NULL,
		 .post_cb = NULL
    };

    ESP_ERROR_CHECK(spi_bus_initialize(HSPI_HOST, &busconfig, 1));

	ESP_ERROR_CHECK(spi_bus_add_device(HSPI_HOST, &dev_config, &handle));

	uint8_t cmd[] = {0x05, 0x0A};

	spi_transaction_t t;
	memset(&t, 0, sizeof(t));       
	t.flags =SPI_TRANS_USE_TXDATA;
	t.length=2 * 8;                   
	t.tx_buffer=cmd;               
	t.user=(void*)0;               
	ret = spi_device_transmit(spi, &t);
	assert( ret == ESP_OK);

	ESP_ERROR_CHECK(spi_bus_remove_device(handle));
	ESP_ERROR_CHECK(spi_bus_free(HSPI_HOST));

}

[ESP_Sprite]

If anything, you're setting SPI_TRANS_USE_TXDATA, which means that the SPI peripheral will get the tx data from the tx_data member, but then you're feeding it a buffer through the tx_buffer member instead. Remove the SPI_TRANS_USE_TXDATA flag and you should be at least a bit closer to working code.