text: /*
   * Author: Jon Trulson <jtrulson@ics.com>
   * Copyright (c) 2016 Intel Corporation.
   *
   * This program and the accompanying materials are made available under the
   * terms of the The MIT License which is available at
   * https://opensource.org/licenses/MIT.
   *
   * SPDX-License-Identifier: MIT
   */
  
  #include <unistd.h>
  #include <stdio.h>
  
  #include "mcp2515.h"
  
  int main(int argc, char **argv)
  {
  //! [Interesting]
  
  #if defined(CONFIG_BOARD_ARDUINO_101)
      // ARDUINO_101 (Quark core) where you must use SPI
      // Instantiate a MCP2515 instance using default SPI bus and pin 10 as CS
      mcp2515_context sensor = mcp2515_init(0, 10);
  #else
      // Instantiate a MCP2515 on SPI bus 0 using a hw CS pin (-1).
      mcp2515_context sensor = mcp2515_init(0, -1);
  #endif
  
      if (!sensor)
      {
          printf("mcp2515_init() failed\n");
          return 1;
      }
  
      printf("Setting loopback mode...\n");
  
      // set the mode to loopback mode.  In loopback mode, transmitted
      // packets are sent directly to an appropriate receive buffer
      // without actually going out onto the CAN bus.
      if (mcp2515_set_opmode(sensor, MCP2515_OPMODE_LOOPBACK))
      {
          printf("mcp2515_set_opmode(loopback) failed.\n");
          return 1;
      }
  
      // lets build up a packet and try loading it.
      uint8_t myPayload[8] = {0, 1, 2, 3, 4, 5, 6, 7};
      printf("Loading a packet of 8 numbers (0-7) into a TX buffer...\n");
      if (mcp2515_load_tx_buffer(sensor, MCP2515_TX_BUFFER0, 0, false, false,
                                 myPayload, 8))
      {
          printf("mcp2515_load_tx_buffer() failed\n");
          return 1;
      }
  
      // now lets try to transmit it
      printf("Transmitting packet...\n");
      upm_result_t rv = 0;
      if ((rv = mcp2515_transmit_buffer(sensor, MCP2515_TX_BUFFER0, true)))
      {
          printf("mcp2515_transmit_buffer() failed with code %d\n", rv);
          return 1;
      }
  
      printf("Transmit successful\n");
  
      // There should now be a packet waiting for us in RXB0
      if (mcp2515_rx_status_msgs(sensor) == MCP2515_RXMSG_RXB0)
      {
          printf("Packet received in RXB0, decoding...\n");
  
          // now lets retrieve it
          MCP2515_MSG_T msg;
          if (mcp2515_get_rx_msg(sensor, MCP2515_RX_BUFFER0, &msg))
          {
              printf("mcp2515_get_rx_msg() failed\n");
              return 1;
          }
  
          mcp2515_print_msg(sensor, &msg);
      }
      else
      {
          printf("No packet found, how strange.\n");
      }
  
      printf("Exiting...\n");
  
      mcp2515_close(sensor);
  //! [Interesting]
  
      return 0;
  }
  