Difference between revisions of "Hammer LED Userspace App"
(Change to Category TCT-Hammer) |
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#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 /*physical address of the GPIO F control register */ | + | #define GPIOF_CON 0x56000050 /* physical address of the GPIO F control register */ |
− | #define GPIOF_DAT 0x56000054 /*physical address of the GPIO F data register */ | + | #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) { | if(argc < 2) { | ||
Line 72: | Line 73: | ||
/* 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 116: | Line 119: | ||
read_result = *((unsigned long *) virt_addr); | read_result = *((unsigned long *) virt_addr); | ||
− | /* make the LED is off when leaving the program */ | + | /* make sure the LED is off when leaving the program */ |
writeval = read_result; | writeval = read_result; | ||
writeval |= (1<<0); /* set GPIO F0 to a value of 1(high-off) */ | writeval |= (1<<0); /* set GPIO F0 to a value of 1(high-off) */ | ||
Line 122: | Line 125: | ||
/* write the modified value to the GPIO F0 data register */ | /* write the modified value to the GPIO F0 data register */ | ||
*((unsigned long *) virt_addr) = writeval; | *((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; | ||
Line 130: | Line 136: | ||
</pre> | </pre> | ||
+ | |||
+ | [[Category:TCT-Hammer]] |
Latest revision as of 09:48, 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; }