Author Topic: spi signals problem  (Read 2326 times)

Offline jalila211

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spi signals problem
« on: January 03, 2015, 01:45:46 pm »
I want to use spi on cubieboard1. after configure the sunxi kernel and compile it,after using modprob I can see spidev0.0 in my dev folder. but when i use some test programs  i cant see any signals in spi pin.
my fex file :
Code: [Select]
spi_used = 1
spi_cs_bitmap = 1
spi_cs0 = port:PI10<3><default><default><default>
spi_sclk = port:PI11<3><default><default><default>
spi_mosi = port:PI12<3><default><default><default>
spi_miso = port:PI13<3><default><default><default>
spi_dev_num = 1

modalias = "spidev"
max_speed_hz = 8000000
bus_num = 1
chip_select = 0
mode = 0
full_duplex = 0
manual_cs = 0
my test code:
Code: [Select]

Example code for SPI access on the pcDuino via C++. This code *should* work
in the future, but as of release, only SPI output works. Data presented on
the MISO pin does not register with the device!

26 Mar 2013 - Mike Hord, SparkFun Electronics

This code is beerware- if you find it useful, please buy me (or, for that
matter, any other SparkFun employee you met) a pint next time you meet us at
the local.


#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <linux/spi/spidev.h>
#include "spi_test.h"

static const char *spi_name = "/dev/spidev0.0";

int main(void)
    int res = 0;  // We can use this to monitor the results of any operation.

    // The very first thing we need to do is make sure that the pins are set
    //   to SPI mode, rather than, say, GPIO mode.
    char path[256];

    for (int i = 10; i<=13; i++)
        // Clear the path variable...
        // ...then assemble the path variable for the current pin mode file...
        sprintf(path, "%s%s%d", GPIO_MODE_PATH, GPIO_FILENAME, i);
        // ...and create a file descriptor...
        int pinMode = open(path, O_RDWR);
        // ...which we then use to set the pin mode to SPI...
        setPinMode(pinMode, SPI);
        // ...and then, close the pinMode file.
    // As usual, we begin the relationship by establishing a file object which
    //   points to the SPI device.
    int spiDev = open(spi_name, O_RDWR);

    // We'll want to configure our SPI hardware before we do anything else. To do
    //   this, we use the ioctl() function. Calls to this function take the form
    //   of a file descriptor, a "command", and a value. The returned value is
    //   always the result of the operation; pass it a pointer to receive a value
    //   requested from the SPI peripheral.

    // Start by setting the mode. If we wanted to *get* the mode, we could
    //   use SPI_IOC_RD_MODE instead. In general, the "WR" can be replaced by
    //   "RD" to fetch rather than write. Also note the somewhat awkward
    //   setting a variable rather than passing the constant. *All* data sent
    //   via ioctl() must be passed by reference!
    int mode = SPI_MODE0;
    ioctl(spiDev, SPI_IOC_WR_MODE, &mode);

    // The maximum speed of the SPI bus can be fetched. You'll find that, on the
    //  pcDuino, it's 12MHz.
    int maxSpeed = 0;
    ioctl(spiDev, SPI_IOC_RD_MAX_SPEED_HZ, &maxSpeed);
    printf("Max speed: %dHz\n", maxSpeed);

    // In rare cases, you may find that a device expects data least significant
    //   bit first; in that case, you'll need to set that up. Writing a 0
    //   indicates MSb first; anything else indicates LSb first.
    int lsb_setting = 0;
    ioctl(spiDev, SPI_IOC_WR_LSB_FIRST, &lsb_setting);

    // Some devices may require more than 8 bits of data per transfer word. The
    //   SPI_IOC_WR_BITS_PER_WORD command allows you to change this; the default,
    //   0, corresponds to 8 bits per word.
    int bits_per_word = 0;
    ioctl(spiDev, SPI_IOC_WR_BITS_PER_WORD, &bits_per_word);

    // Okay, now that we're all set up, we can start thinking about transferring
    //   data. This, too, is done through ioctl(); in this case, there's a special
    //   struct (spi_ioc_transfer) defined in spidev.h which holds the needful
    //   info for completing a transfer. Its members are:
    //    * tx_buf - a pointer to the data to be transferred
    //    * rx_buf - a pointer to storage for received data
    //    * len - length in bytes of tx and rx buffers
    //    * speed_hz - the clock speed, in Hz
    //    * delay_usecs - delay between last bit and deassertion of CS
    //    * bits_per_word - override global word length for this transfer
    //    * cs_change - strobe chip select between transfers?
    //    * pad - ??? leave it alone.

    // For this example, we'll be reading the address location of an ADXL362
    //   accelerometer, then writing a value to a register and reading it back.
    //   We'll do two transfers, for ease of data handling: the first will
    //   transfer the "read register" command (0x0B) and the address (0x02), the
    //   second will dump the response back into the same buffer.

    struct spi_ioc_transfer xfer;
    memset(&xfer, 0, sizeof(xfer));
    char dataBuffer[3];
    char rxBuffer[3];
    dataBuffer[0] = 0x0B;
    dataBuffer[1] = 0x02;
    dataBuffer[2] = 0x00;
    xfer.tx_buf = (unsigned long)dataBuffer;
    xfer.rx_buf = (unsigned long)rxBuffer;
    xfer.len = 3;
    xfer.speed_hz = 500000;
    xfer.cs_change = 1;
    xfer.bits_per_word = 8;
    int i=0;
        res = ioctl(spiDev, SPI_IOC_MESSAGE(1), &xfer);
        printf("SPI result: %d\n", res);
    printf("Device ID: %d - %d - %d\n", rxBuffer[2], rxBuffer[1], rxBuffer[0]);

void setPinMode(int pinID, int mode)
    writeFile(pinID, mode);

// While it seems okay to only *read* the first value from the file, you
//   seemingly must write four bytes to the file to get the I/O setting to
//   work properly. This function does that.
void writeFile(int fileID, int value)
    char buffer[4];  // A place to build our four-byte string.
    memset((void *)buffer, 0, sizeof(buffer)); // clear the buffer out.
    sprintf(buffer, "%d", value);
    lseek(fileID, 0, SEEK_SET);   // Make sure we're at the top of the file!
    int res = write(fileID, buffer, sizeof(buffer));