ESP32 Forum

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#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"
#include "freertos/queue.h"

#include "lwip/sockets.h"
#include "lwip/dns.h"
#include "lwip/netdb.h"
#include "lwip/igmp.h"

#include "esp_wifi.h"
#include "esp_system.h"
#include "esp_event.h"
#include "esp_event_loop.h"
#include "nvs_flash.h"
#include "soc/rtc_cntl_reg.h"
#include "rom/cache.h"
#include "driver/spi_slave.h"
#include "esp_log.h"
#include "esp_spi_flash.h"

#define GPIO_MOSI 12
#define GPIO_MISO 13
#define GPIO_SCLK 15
#define GPIO_CS 14



//Main application
void app_main()
{


    //Configuration for the SPI bus
    spi_bus_config_t buscfg={
        .mosi_io_num=GPIO_MOSI,
        .miso_io_num=GPIO_MISO,
        .sclk_io_num=GPIO_SCLK
    };

    //Configuration for the SPI slave interface
    spi_slave_interface_config_t slvcfg={
        .mode=0,
        .spics_io_num=GPIO_CS,
        .queue_size=3,
        .flags=0,
    };


    //Enable pull-ups on SPI lines so we don't detect rogue pulses when no master is connected.
    gpio_set_pull_mode(GPIO_MOSI, GPIO_PULLUP_ONLY);
    gpio_set_pull_mode(GPIO_SCLK, GPIO_PULLUP_ONLY);
    gpio_set_pull_mode(GPIO_CS, GPIO_PULLUP_ONLY);

    //Initialize SPI slave interface
	spi_slave_initialize(VSPI_HOST, &buscfg, &slvcfg, 1);
	

    char recvbuf[129]="";

    memset(recvbuf, 0, 33);
    spi_slave_transaction_t t;
    memset(&t, 0, sizeof(t));

    while(1) {
        //Clear receive buffer, set send buffer to something sane
		memset(recvbuf, 0x34, 129);
		
        //Set up a transaction of 128 bytes to send/receive
        t.length=128*8;
        t.rx_buffer=recvbuf;

		spi_slave_transmit(VSPI_HOST, &t, portMAX_DELAY);
		
		printf("Received: %s\n", recvbuf);

    }

}

Code: Select all

    char sendbuf[3]="";
    char recvbuf[3]="";
    
    sendbuf[0]=0x31;
    sendbuf[1]=0x32;
    sendbuf[2]=0x33;
    
    recvbuf[0]=0;
    recvbuf[1]=0;
    recvbuf[2]=0;
    
    spi_slave_transaction_t t;
    
    t.length=3*8;
    t.tx_buffer=sendbuf;
    t.rx_buffer=recvbuf;
    

Code: Select all

heap_caps_malloc(3, MALLOC_CAP_DMA);

Code: Select all

char *POINTER_T = heap_caps_malloc(3, MALLOC_CAP_DMA);
    
    char *POINTER_R = heap_caps_malloc(3, MALLOC_CAP_DMA);
    
    
    
    while(1) {
		spi_slave_transaction_t t;
		t.length=3*8;
		t.tx_buffer=POINTER_T;
		t.rx_buffer=POINTER_R;
        
		spi_slave_transmit(HSPI_HOST, &t, portMAX_DELAY);
		
		printf("%d",*POINTER_R);
		printf("\n");
    }