Differences

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--- en:xu3_hardware_spi [2015/07/31 16:15]
odroid [Reading the SPI Flash device ID on Expansion-Board]
+++ en:xu3_hardware_spi [2016/12/24 12:15] (current)
odroid [Reading the SPI Flash device ID on Expansion-Board]
@@ Line 1: / Line 1: @@
+====== SPI ======
+This page introduces how you can use SPI interface using Expansion Board.
+===== Reading the SPI Flash device ID on Expansion-Board =====
+To use spidev on your **ODROID-XU3** you should fix device tree source.
+<WRAP center round important 100%>
+To use the SPI, you first need to update the kernel version to "3.10.82" or higher.
+  sudo apt-get update && sudo apt-get dist-upgrade
+</WRAP>
+<WRAP center round important 100%>
+SPI MODE 3 doesn't work by unknown reason. Please try to use the SPI MODE 0.
+</WRAP>
+=== How to enable driver (Only Ubuntu 16.04 or higher is required) ===
+Edit /etc/modprobe.d/blacklist-odroid.conf to comment out following two ines.
+<code>
+blacklist spidev
+blacklist spi_s3c64xx
+</code>
+Reboot.
+  reboot
+Check your SPI node.
+  ls /dev/spidev*
+=== Compile & run SPI test example source code ===
+  gcc -o spidev_test spidev_test.c
+<code>
+odroid@odroid:~$ ./spidev_test
+spi mode: 0
+bits per word: 8
+max speed: 500000 Hz (500 KHz)
+34 34 34
+</code>
+If you tie the MOSI and MISO pins, the output is "AB 00 00 00".\\
+We call it loopback test.
+<file c spidev_test.c>
+/*
+ * SPI testing utility (using spidev driver)
+ *
+ * Copyright (c) 2007  MontaVista Software, Inc.
+ * Copyright (c) 2007  Anton Vorontsov <avorontsov@ru.mvista.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ * Cross-compile with cross-gcc -I/path/to/cross-kernel/include
+ */
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/spi/spidev.h>
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
+static void pabort(const char *s)
+{
+        perror(s);
+        abort();
+}
+static const char *device = "/dev/spidev1.0";
+static uint8_t mode;
+static uint8_t bits = 8;
+static uint32_t speed = 500000;
+static void transfer(int fd)
+{
+        int ret;
+        uint8_t tx[] = {
+xAB, 0x00, 0x00, 0x00
+        };
+        uint8_t rx[ARRAY_SIZE(tx)] = {0, };
+        struct spi_ioc_transfer tr[2];
+        tr[0].tx_buf = (unsigned long)tx;
+        tr[0].rx_buf = (unsigned long)rx;
+        tr[0].len = ARRAY_SIZE(tx);
+        tr[0].speed_hz = speed;
+        tr[0].bits_per_word = bits;
+        tr[0].delay_usecs = 0;
+        tr[0].cs_change = 0;
+        tr[1].tx_buf = (unsigned long)tx;
+        tr[1].rx_buf = (unsigned long)rx;
+        tr[1].len = ARRAY_SIZE(tx);
+        tr[1].speed_hz = speed;
+        tr[1].bits_per_word = bits;
+        tr[1].delay_usecs = 0;
+        tr[1].cs_change = 0;
+        ret = ioctl(fd, SPI_IOC_MESSAGE(2), tr);
+        if (ret < 1)
+                pabort("can't send spi message");
+        for (ret = 0; ret < ARRAY_SIZE(tx); ret++) {
+                if (!(ret % 6))
+                        puts("");
+                printf("%.2X ", rx[ret]);
+        }
+        puts("");
+}
+int main(void)
+{
+        int ret = 0;
+        int fd;
+        fd = open(device, O_RDWR);
+        if (fd < 0)
+                pabort("can't open device");
+        /*
+         * spi mode
+         */
+        ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
+        if (ret == -1)
+                pabort("can't set spi mode");
+        ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);
+        if (ret == -1)
+                pabort("can't get spi mode");
+        /*
+         * bits per word
+         */
+        ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
+        if (ret == -1)
+                pabort("can't set bits per word");
+        ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
+        if (ret == -1)
+                pabort("can't get bits per word");
+        /*
+         * max speed hz
+         */
+        ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
+        if (ret == -1)
+                pabort("can't set max speed hz");
+        ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
+        if (ret == -1)
+                pabort("can't get max speed hz");
+        printf("spi mode: %d\n", mode);
+        printf("bits per word: %d\n", bits);
+        printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);
+        transfer(fd);
+        close(fd);
+        return ret;
+}
+</file>
+**If you want to use 16bit/32bit length protocol with different SPI speed on XU4, refer this [[en:c1_hardware_spidev|c1_hardware_spidev]].**