Difference between revisions of "Hammer LED Userspace App"
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(Change to Category TCT-Hammer) |
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| Line 13: | Line 13: | ||
#chmod 755 ledblink | #chmod 755 ledblink | ||
#./ledblink | #./ledblink | ||
| + | |||
| + | Usage: ./ledblink { seconds } | ||
| + | seconds : number of seconds to blink | ||
| + | |||
| + | #./ledblink 20 | ||
</pre> | </pre> | ||
| − | the | + | this will cause the onboard LED to blink for 20 seconds |
| + | |||
==Source== | ==Source== | ||
| Line 43: | Line 49: | ||
#include <stdio.h> | #include <stdio.h> | ||
#include <stdlib.h> | #include <stdlib.h> | ||
| − | |||
| − | |||
| − | |||
| − | |||
#include <fcntl.h> | #include <fcntl.h> | ||
| − | |||
| − | |||
| − | |||
#include <sys/mman.h> | #include <sys/mman.h> | ||
| − | + | #define MAP_SIZE 4096UL /* the size of one page of virtual memory */ | |
| − | + | #define MAP_MASK (MAP_SIZE - 1) /* mask used for the one page of virtual memory */ | |
| − | + | ||
| − | #define MAP_SIZE 4096UL | + | |
| − | #define MAP_MASK (MAP_SIZE - 1) | + | |
| − | #define GPIOF_CON 0x56000050 | + | #define GPIOF_CON 0x56000050 /* physical address of the GPIO F control register */ |
| − | #define GPIOF_DAT 0x56000054 | + | #define GPIOF_DAT 0x56000054 /* physical address of the GPIO F data register */ |
| − | + | ||
int main(int argc, char **argv) { | int main(int argc, char **argv) { | ||
| − | int fd; | + | int fd,count; |
void *map_base, *virt_addr; | void *map_base, *virt_addr; | ||
| − | + | unsigned long read_result, writeval; | |
| − | + | ||
| + | if(argc < 2) { | ||
| + | fprintf(stderr, "\nUsage:\t%s { seconds }\n" | ||
| + | "\tseconds : number of seconds to blink\n\n", | ||
| + | argv[0]); | ||
| + | exit(1); | ||
| + | } | ||
| + | |||
| + | count = strtoul(argv[1], 0, 0); | ||
/* open the memory device file descriptor */ | /* open the memory device file descriptor */ | ||
| − | if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) | + | if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) |
| + | return -1; | ||
/* Map one page */ | /* Map one page */ | ||
map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, GPIOF_CON & ~MAP_MASK); | map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, GPIOF_CON & ~MAP_MASK); | ||
| − | if(map_base == (void *) -1) | + | if(map_base == (void *) -1) |
| + | return -1; | ||
/* set the virtual memory address to the GPIO F control register */ | /* set the virtual memory address to the GPIO F control register */ | ||
| Line 93: | Line 98: | ||
virt_addr = map_base + (GPIOF_DAT & MAP_MASK); | virt_addr = map_base + (GPIOF_DAT & MAP_MASK); | ||
| − | for ( count | + | for ( count ; count > 0 ; count--) { |
/* read the current value for GPIO F data register */ | /* read the current value for GPIO F data register */ | ||
| Line 109: | Line 114: | ||
} | } | ||
| − | + | ||
| − | if(munmap(map_base, MAP_SIZE) == -1) | + | |
| + | /* read the current value for GPIO F control register */ | ||
| + | read_result = *((unsigned long *) virt_addr); | ||
| + | |||
| + | /* make sure the LED is off when leaving the program */ | ||
| + | writeval = read_result; | ||
| + | writeval |= (1<<0); /* set GPIO F0 to a value of 1(high-off) */ | ||
| + | |||
| + | /* write the modified value to the GPIO F0 data register */ | ||
| + | *((unsigned long *) virt_addr) = writeval; | ||
| + | |||
| + | /* unmap the virtual memory before exiting the program */ | ||
| + | if(munmap(map_base, MAP_SIZE) == -1) | ||
| + | return -1; | ||
| + | |||
close(fd); | close(fd); | ||
return 0; | return 0; | ||
} | } | ||
| + | |||
</pre> | </pre> | ||
| + | |||
| + | [[Category:TCT-Hammer]] | ||
Latest revision as of 16:48, 14 May 2011
This is an example program that uses the /dev/mem device node to access the physical memory registers directly(source)
Usage
to compile the source use your toolchain command line
#arm-linux-uclibc-gcc -o ledblink ledblink.c
then transfer the ledblink binary to the hammer file system. make sure that the permissions on the file are set to executable.
#chmod 755 ledblink
#./ledblink
Usage: ./ledblink { seconds }
seconds : number of seconds to blink
#./ledblink 20
this will cause the onboard LED to blink for 20 seconds
Source
/*
* ledblink.c: Simple program to blink a led on GPIO F0
*
* Copyright (c) 2008 TinCanTools
* David Anders <danders@amltd.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, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/mman.h>
#define MAP_SIZE 4096UL /* the size of one page of virtual memory */
#define MAP_MASK (MAP_SIZE - 1) /* mask used for the one page of virtual memory */
#define GPIOF_CON 0x56000050 /* physical address of the GPIO F control register */
#define GPIOF_DAT 0x56000054 /* physical address of the GPIO F data register */
int main(int argc, char **argv) {
int fd,count;
void *map_base, *virt_addr;
unsigned long read_result, writeval;
if(argc < 2) {
fprintf(stderr, "\nUsage:\t%s { seconds }\n"
"\tseconds : number of seconds to blink\n\n",
argv[0]);
exit(1);
}
count = strtoul(argv[1], 0, 0);
/* open the memory device file descriptor */
if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1)
return -1;
/* Map one page */
map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, GPIOF_CON & ~MAP_MASK);
if(map_base == (void *) -1)
return -1;
/* set the virtual memory address to the GPIO F control register */
virt_addr = map_base + (GPIOF_CON & MAP_MASK);
/* read the current value for GPIO F control register */
read_result = *((unsigned long *) virt_addr);
writeval = read_result;
writeval &= ~0x03; /* mask off the first two bits */
writeval |= 0x01; /* set gpio f0 to output with value of 0x01 */
/* write the modified value to GPIO F0 control register to set GPIO F0 to output */
*((unsigned long *) virt_addr) = writeval;
/* change virtual memory address to GPIO F data register */
virt_addr = map_base + (GPIOF_DAT & MAP_MASK);
for ( count ; count > 0 ; count--) {
/* read the current value for GPIO F data register */
read_result = *((unsigned long *) virt_addr);
writeval = read_result;
if ( (read_result&(1<<0)) )
writeval &= ~(1<<0); /* set GPIO F0 to a value of 0(low-on) */
else
writeval |= (1<<0); /* set GPIO F0 to a value of 1(high-off) */
/* write the modified value to the GPIO F0 data register */
*((unsigned long *) virt_addr) = writeval;
sleep(1);
}
/* read the current value for GPIO F control register */
read_result = *((unsigned long *) virt_addr);
/* make sure the LED is off when leaving the program */
writeval = read_result;
writeval |= (1<<0); /* set GPIO F0 to a value of 1(high-off) */
/* write the modified value to the GPIO F0 data register */
*((unsigned long *) virt_addr) = writeval;
/* unmap the virtual memory before exiting the program */
if(munmap(map_base, MAP_SIZE) == -1)
return -1;
close(fd);
return 0;
}
