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#include <stdint.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <getopt.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <linux/types.h>
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#include <linux/spi/spidev.h>
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#include <iostream>
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#include <chrono>
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// ... test framework, etc.
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const size_t SPI_BUFFER_SIZE = 4;
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uint16_t spi_tx_buffer[SPI_BUFFER_SIZE];
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uint16_t spi_rx_buffer[SPI_BUFFER_SIZE];
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struct spi_ioc_transfer xfer[1];
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int spi_init()
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{
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int file;
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uint8_t mode, lsb, bits;
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uint32_t speed;
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if ((file = open("/dev/spidev32766.0", O_RDWR)) < 0)
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{
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printf("Failed to open the bus.");
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return -1;
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}
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// ... mode reading and writing
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printf("file: spi mode %d, %d bits %sper word, %d Hz max\n", mode, bits, lsb ? "(lsb first) " : "", speed);
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memset(xfer, 0, sizeof(spi_ioc_transfer));
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xfer[0].tx_buf = (unsigned long)spi_tx_buffer;
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xfer[0].len = 20; // Length of command to write
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xfer[0].cs_change = 1; // Do NOT Keep CS activated
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xfer[0].delay_usecs = 0;
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xfer[0].speed_hz = 100000;
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xfer[0].bits_per_word = 16;
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return file;
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}
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uint16_t* spi_read(int file)
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{
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int status;
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memset(spi_tx_buffer, 0, sizeof spi_tx_buffer);
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memset(spi_rx_buffer, 0, sizeof spi_rx_buffer);
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spi_tx_buffer[0] = 0x8330;
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xfer[0].tx_buf = (unsigned long)spi_tx_buffer;
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xfer[0].len = 2; // Length of command to write/read
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xfer[0].rx_buf = (unsigned long)spi_rx_buffer;
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status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);
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if (status < 0)
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{
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perror("SPI_IOC_MESSAGE");
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}
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// Allow way more than enough time for transfer to occur
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sleep(1);
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printf("rx: ");
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for (uint16_t i = 0; i < SPI_BUFFER_SIZE; i++)
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{
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printf("%04X ", spi_rx_buffer[i]);
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}
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printf("\n");
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return spi_rx_buffer;
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}
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void main()
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{
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int spidev_fd = spi_init();
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if (spidev_fd < 0)
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{
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printf("Failed to open!");
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return;
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}
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// Timeout after 10 seconds
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std::cout << "STARTING SPI" << std::endl;
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auto timeout_time = std::chrono::high_resolution_clock::now() + std::chrono::seconds(10);
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while (std::chrono::high_resolution_clock::now() < timeout_time)
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{
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spi_read(spidev_fd); //reading the address 0xE60E
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std::cout << "BUFFER: " << spi_rx_buffer << std::endl;
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usleep(100000);
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}
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close(spidev_fd);
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}
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