Beaglebone Black [BBB] Read Shared memory from PRU
marcu...@gmail.com
i wrote a PRU Programm where i read some Sensors and calculate something. Then i save the Data in the shared RAM.
But how can i read the memory from the ARM? is it possible to read it from an c programm or shell? edit: i programm the PRU with this method: https://markayoder.github.io/PRUCookbook/index.html
Greetings Marcus
Gerhard Hoffmann
i wrote a PRU Programm where i read some Sensors and calculate something. Then i save the Data in the shared RAM.
But how can i read the memory from the ARM? is it possible to read it from an c programm or shell? edit: i programm the PRU with this method: https://markayoder.github.io/PRUCookbook/index.html
Greetings Marcus
That is experimental code I have not seen for some months (must first do the hardware)
It shows how to mmap the PRU / shared ram into the ARM memory space and dump the contents to files.
The dumps are somewhat annotated with the data structures I use.
This is ad hoc ripped from the source files, not intended to be
compiled as it is.
#include <sys/types.h> /* type definitions used by
many programs */
#include <stdio.h> /* standard IO functions */
#include <stdlib.h> /* commonly used functions,
EXIT_SUCCESS and EXIT_FAILURE */
#include <errno.h>
#include <string.h>
#include <math.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include "ltcsrv.h" /* for panic() */
#include "pru_if.h" /* to enforce consistency with .c */
#include "cmnd_stat_codes.h"
#define ADC_BUFFER_SIZE (16*1024)
int dev_mem_fd;
volatile int *shared_ram;
volatile int *pru_ram; // the 8 KB local data = 2
KWORDS
int adc_buffer[ADC_BUFFER_SIZE];
int cmnd_to_send;
int open_pru(){
int i;
//if (verbose) printf("enter open_pru()\n");
if (init_cpld_pins()) return 1;
//if(verbose) printf("starting pru 0\n");
// if (!start_pru()) return 1;
// printf("sleeping 1 s\n");
// sleep(1);
// map the shared ram into our virtual memory
//printf("mapping...\n");
dev_mem_fd = open("/dev/mem",O_RDWR | O_SYNC);
// mmap params:
// addres where the kernel creates the mapping. NULL= do as
you like
// size of the mapped region 12288 = 12 KBytes
// protection
// flags
// file descriptor von /dev/mem
// pru-base = 0x4A30_0000, shared ram starts at +0x10000
shared_ram = (int *) mmap(NULL, 12*1024, PROT_READ |
PROT_WRITE, MAP_SHARED,
dev_mem_fd, 0x4A300000 + 0x10000);
if (-1 == (int)shared_ram) panic("could not mmap() shared PRU
ram");
// both PRU local data rams together
pru_ram = (int *) mmap(NULL, 2*8*1024, PROT_READ | PROT_WRITE,
MAP_SHARED,
dev_mem_fd, 0x4A300000 + 0x00000);
if (-1 == (int)pru_ram) panic("could not mmap() local PRU
rams");
for (i=0; i< ADC_BUFFER_SIZE; i++){ // 12 KB are 3 Kwords
adc_buffer[i] = 0;
}
return 0;
}
int close_pru(void){
// FIXME: shared RAM must be un-mapped and file descriptors
should be closed
if (verbose) printf("enter close_pru()\n");
// if (!stop_pru()) return 1;
if (verbose) printf("leaving close_pru()\n");
return 0;
}
void copy_shared_ram_to_file(char *fn){
FILE * phyle;
int i, j;
phyle = fopen(fn, "w"); // FIXME return value
fprintf(phyle, "%s\n", fn);
fprintf(phyle, "byte index dec byte index hex word index
content\n\n");
for (i=0; i< 3*1024; i++){ // 12 KB are 3 Kwords
fprintf(phyle, "\n%12d %8x %8x = 0x%8x %12d", 4*i,
4*i, i, shared_ram[i], shared_ram[i]);
switch(i){
case 0: fprintf(phyle, " unused");
break;
case COMMAND: fprintf(phyle, " command");
break;
case STATUS: fprintf(phyle, " status"); break;
case PARAM1: fprintf(phyle, " param1"); break;
case PARAM2: fprintf(phyle, " param2"); break;
case PARAM3: fprintf(phyle, " param3"); break;
case TEST1: fprintf(phyle, " test1");
break;
case TEST2: fprintf(phyle, " test2");
break;
case TEST3: fprintf(phyle, " test3");
break;
case PING_FULL: fprintf(phyle, " ping_full");
break;
case PONG_FULL: fprintf(phyle, " pong_full");
break;
case PING: fprintf(phyle, " ping buffer
start"); break;
case PONG: fprintf(phyle, " pong buffer
start"); break;
}
}
fclose(phyle); // FIXME return value
}
// thats for all the 2*8 KBytes
void copy_pru_ram_to_file(char *fn){
FILE * phyle;
int i, j;
phyle = fopen(fn, "w"); // FIXME return value
fprintf(phyle, "%s\n", fn);
fprintf(phyle, "byte index word index content all
hex\n\n");
fprintf(phyle, "stack lowest and data nil pointer\n");
for (i=0; i< 4*1024; i++){ // 2 * 8 KB are 4 Kwords
if (0x100/4 == i) { fprintf(phyle, "\nstack
highest - heap lowest\n"); }
else if (0x200/4 == i) { fprintf(phyle, "\nheap
highest\n"); }
fprintf(phyle, "%8x %8x = %8x\n", 4*i, i, pru_ram[i]);
}
fclose(phyle); // FIXME return value
}
hope it helps somewhat.
regards,
Gerhard
Mark A. Yoder
Walter Cromer
Walter Cromer
When I look for /dev/mem it doesn't exist whether logged in as debian or root
Mark A. Yoder
Walter Cromer
Walter Cromer
Dennis Lee Bieber
gmane.comp.hardware.beagleboard.user Walter Cromer
>I checked with ls -ls /dev/mem logged in as debian and it's there.
>
0 crw-r----- 1 root kmem 1, 1 Apr 30 12:06 /dev/mem
debian@beaglebone:~$
debian@beaglebone:~$ groups
systemd-journal input bluetooth netdev i2c remoteproc eqep pwm cloud9ide
xenomai weston-launch tisdk docker iio spi admin gpio
That is what my BBB shows.
Owner (root) has R/W permission
Group (kmem) has Read-Only permission.
The debian account has kmem group access.
From your earlier post...
> fd = open ("/dev/mem", O_RDWR | O_SYNC);
kmem group. What happens if you attempt to open /dev/mem for read-only
access?
--
Dennis L Bieber