gistfile1.txt

/* Copyright 2019 SiFive, Inc */
/* SPDX-License-Identifier: Apache-2.0 */

#include <stdio.h>

#include <metal/spi.h>
#include <metal/gpio.h>

struct metal_spi *spi = 0;
struct metal_gpio *gpio_device = 0;

struct metal_spi_config config = {
                                  .protocol = METAL_SPI_SINGLE,
                                  .polarity = 0,
                                  .phase = 0,
                                  .little_endian = 0,
                                  .cs_active_high = 0,
                                  .csid = 0,
};

void wait_handshake() {
  while (1) {
    int handshake = metal_gpio_get_input_pin(gpio_device, 10);
    if (handshake)
      printf("waiting\n");
    else
      break;
  }
}

void transfer_4(char *tx_buf, char *rx_buf) {
  metal_gpio_set_pin(gpio_device, 9, 0); //chip select?

  printf("Sending\n");
  int code = metal_spi_transfer(spi, &config, 4, tx_buf, rx_buf);
  printf("%i %i %i %i\n", rx_buf[0], rx_buf[1], rx_buf[2], rx_buf[3]);
  printf("Done, code: %i\n", code);

  metal_gpio_set_pin(gpio_device, 9, 1);
}

int init() {
    //set CS enable? (low is active?)
    gpio_device = metal_gpio_get_device(0);
    metal_gpio_enable_output(gpio_device, 9);

    //set handshape pin to input
    metal_gpio_enable_input(gpio_device, 10);  

	/* Get SPI 1 */
    printf("Trying to get device\n");
    while (spi == NULL) {
      spi = metal_spi_get_device(1);
    }

	if(spi == NULL) {
		printf("Failed to get spi device\n");
        return 0;
	}

	/* Initialize the SPI device to 100_000 baud */
	metal_spi_init(spi, 1000);

    return 1;
}

int main() {
	printf("METAL SPI Driver ESP32 Demo\n");

    if (!init()) {
      printf("init fail\n");
      return -1;
    }

    wait_handshake();
    {
      char tx_buf[4] = {0x2, 0, 0, 0};
      char rx_buf[4] = {0, 0, 0, 0};
      transfer_4(tx_buf, rx_buf);
    }

    wait_handshake();
    {
      char tx_buf[4] = {4, 0, 0, 0x41};
      char rx_buf[4] = {0, 0, 0, 0};
      transfer_4(tx_buf, rx_buf);
    }

    wait_handshake();
    {
      char tx_buf[4] = {'A', 'T', '\r', '\n'};
      char rx_buf[4] = {0, 0, 0, 0};
      transfer_4(tx_buf, rx_buf);
    }

    wait_handshake();
    {
      char tx_buf[4] = {0x2, 0, 0, 0};
      char rx_buf[4] = {0, 0, 0, 0};
      transfer_4(tx_buf, rx_buf);
    }

    wait_handshake();
    {
      char tx_buf[4] = {0, 0, 0, 0};
      char rx_buf[4] = {0, 0, 0, 0};
      transfer_4(tx_buf, rx_buf);
    }

	return 0;
}