TS-8390-47XX Backlight: Difference between revisions
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The backlight brightness | The backlight brightness on our off the shelf LCD products use the LCD_PWM output. This example takes an integer percentage as the only argument which will set the brightness. | ||
<source lang=c> | <source lang=c> |
Latest revision as of 11:07, 25 March 2014
The backlight brightness on our off the shelf LCD products use the LCD_PWM output. This example takes an integer percentage as the only argument which will set the brightness.
/* Compile with:
* gcc name.c -o output -mcpu=arm9
*/
#include <stdio.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <assert.h>
#include <fcntl.h>
volatile uint32_t *mvpwmregs = 0;
void set_brightness(int pct)
{
if(mvpwmregs == 0) {
int mem = open("/dev/mem", O_RDWR|O_SYNC);
assert(mem != -1);
mvpwmregs = (unsigned int *) mmap(0, 4096,
PROT_READ | PROT_WRITE, MAP_SHARED, mem, 0xd401a000);
}
// duty cycle floor is 57, max is 128
mvpwmregs[0x004/4] = 57 + ((pct * 71)/100);
}
int main(int argc, char **argv)
{
set_brightness(atoi(argv[1]));
return 0;
}