wiringPi_Blueberry/examples/spiSpeed.c

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2023-08-11 15:53:17 +08:00
/*
* spiSpeed.c:
* Code to measure the SPI speed/latency.
* Copyright (c) 2014 Gordon Henderson
***********************************************************************
* This file is part of wiringPi:
* https://projects.drogon.net/raspberry-pi/wiringpi/
*
* wiringPi is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* wiringPi is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with wiringPi.
* If not, see <http://www.gnu.org/licenses/>.
***********************************************************************
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
//#include <fcntl.h>
//#include <sys/ioctl.h>
//#include <linux/spi/spidev.h>
#include <wiringPi.h>
#include <wiringPiSPI.h>
#define TRUE (1==1)
#define FALSE (!TRUE)
#define SPI_CHAN 0
#define NUM_TIMES 100
#define MAX_SIZE (1024*1024)
static int myFd ;
void spiSetup (int speed)
{
if ((myFd = wiringPiSPISetup (SPI_CHAN, speed)) < 0)
{
fprintf (stderr, "Can't open the SPI bus: %s\n", strerror (errno)) ;
exit (EXIT_FAILURE) ;
}
}
int main (void)
{
int speed, times, size ;
unsigned int start, end ;
int spiFail ;
unsigned char *myData ;
double timePerTransaction, perfectTimePerTransaction, dataSpeed ;
if ((myData = malloc (MAX_SIZE)) == NULL)
{
fprintf (stderr, "Unable to allocate buffer: %s\n", strerror (errno)) ;
exit (EXIT_FAILURE) ;
}
wiringPiSetup () ;
for (speed = 1 ; speed <= 32 ; speed *= 2)
{
printf ("+-------+--------+----------+----------+-----------+------------+\n") ;
printf ("| MHz | Size | mS/Trans | TpS | Mb/Sec | Latency mS |\n") ;
printf ("+-------+--------+----------+----------+-----------+------------+\n") ;
spiFail = FALSE ;
spiSetup (speed * 1000000) ;
for (size = 1 ; size <= MAX_SIZE ; size *= 2)
{
printf ("| %5d | %6d ", speed, size) ;
start = millis () ;
for (times = 0 ; times < NUM_TIMES ; ++times)
if (wiringPiSPIDataRW (SPI_CHAN, myData, size) == -1)
{
printf ("SPI failure: %s\n", strerror (errno)) ;
spiFail = TRUE ;
break ;
}
end = millis () ;
if (spiFail)
break ;
timePerTransaction = ((double)(end - start) / (double)NUM_TIMES) / 1000.0 ;
dataSpeed = (double)(size * 8) / (1024.0 * 1024.0) / timePerTransaction ;
perfectTimePerTransaction = ((double)(size * 8)) / ((double)(speed * 1000000)) ;
printf ("| %8.3f ", timePerTransaction * 1000.0) ;
printf ("| %8.1f ", 1.0 / timePerTransaction) ;
printf ("| %9.5f ", dataSpeed) ;
printf ("| %8.5f ", (timePerTransaction - perfectTimePerTransaction) * 1000.0) ;
printf ("|\n") ;
}
close (myFd) ;
printf ("+-------+--------+----------+----------+-----------+------------+\n") ;
printf ("\n") ;
}
return 0 ;
}