Hi all,
I made the following program for generating the square wave of 1MHz using DM3730 but i get a lot of jitter in generation of square wave
and do not get the required frequency even. Please look into it and suggest methods if possible. Actually I want to generate wave upto
20MHz or so…
My observation
for usleep = 10^6, I get 0.5 hertz
for usleep = 10^4, I get 50 hertz
for usleep = 10^2, I get 1.5 Kilo hertz,
for usleep = 1, I get 1.5 Kilo hertz,
Please suggest some program to generate square wave faithfully upto a frequency of 20MHz or so…
The code used by me is as follows:
#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
int main() {
int fd = open("/dev/mem", O_RDWR | O_SYNC);
if (fd < 0) {
printf(“Could not open memory\n”);
return 0;
}
// Pad configuration
volatile ulong pinconf;
pinconf = (ulong) mmap(NULL, 0x10000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0x48000000);
if (pinconf == MAP_FAILED) {
printf(“Pinconf Mapping failed\n”);
close(fd);
return 0;
}
// Configure ONE Expansion HEADER PIN AS OUTPUT FOR SOC.
//CONFIGURE ONE EXPANSION HEADER PIN AS OUTPUT FOR EOC
//CONFIGURE ONE EXPANSION HEADER PINS AS BIDIRECTIONAL
pinconf[0x2158/4] = 0x011C011C; //PIN CONFIGURED AS BIDIRECTIONAL
pinconf[0x215C/4] = 0x011C011C; //PIN CONFIGURED AS
pinconf[0x2160/4] = 0x011C011C; //PIN CONFIGURED AS
pinconf[0x2164/4] = 0x011C011C; //PIN CONFIGURED AS
pinconf[0x2168/4] = 0x011C011C; //PIN CONFIGURED AS
pinconf[0x216C/4] = 0x011C011C; //PIN CONFIGURED AS
pinconf[0x2170/4] = 0x011C011C; //PIN CONFIGURED AS
pinconf[0x2188/4] = 0x011C011C; //PIN CONFIGURED AS
close(fd);
fd = open("/dev/mem", O_RDWR | O_SYNC);
// GPIO Configuration: configure are input —FOR ADC INPUT DATA
volatile ulong gpio;
gpio = (ulong) mmap(NULL, 0x10000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0x49050000);
if (gpio == MAP_FAILED) {
printf(“Gpio Mapping failed\n”);
close(fd);
return 0;
}
// Configure all GPIO pins on bank 5 as OUTPUT
gpio[0x6034/4] = 0x00000000;
int c=0;
int count;
for(;
{
gpio[0x603c/4] = 0xffffffff;
usleep(1);
gpio[0x603c/4] = 0x00000000;
usleep(1);
}
}
. Just try to compile it and see