TS-8390-47XX Backlight: Difference between revisions
From embeddedTS Manuals
(Created page with "The backlight brightness can be adjusted by controlling the duty cycle of PWM on the processor DIO. This example takes an integer percentage as the only argument which will s...") |
No edit summary |
||
| Line 2: | Line 2: | ||
<source lang=c> | <source lang=c> | ||
/* Compile with: | |||
* gcc name.c -o output -mcpu=arm9 | |||
*/ | |||
#include <stdio.h> | #include <stdio.h> | ||
#include <stdint.h> | #include <stdint.h> | ||
Revision as of 11:04, 25 March 2014
The backlight brightness can be adjusted by controlling the duty cycle of PWM on the processor DIO. 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;
}