GP32 Keeping Real Time

[pea]

Hi all,

I need to keep accurate time at better resolution than 1/64 second (available with RTC). Perhaps up to 1/200 of a second. Any ideas?

Cheers,
Peter

 

[loki666]

Hi all,

I need to keep accurate time at better resolution than 1/64 second (available with RTC). Perhaps up to 1/200 of a second. Any ideas?

Cheers,
Peter

​

use a timer (cf s3c2400 Refernce Manual)

 

[Squidge]

Use a hardware timer, you can then just prescale the main clock.

 

[Franxis]

With GPSDK, you can solve the bugs with GpClockSpeedChange(). Then you can use GpTickCountGet() accurately to get milliseconds:

void gpClockSpeedChange(int freq, int magic, int div)
{
#define rTCFG0 (*(volatile unsigned *)0x15100000)
#define rTCFG1 (*(volatile unsigned *)0x15100004)
#define rTCNTB4 (*(volatile unsigned *)0x1510003c)
unsigned int pclk;
unsigned int prescaler0;

/* Change CPU Speed */
GpClockSpeedChange(freq, magic, div);
pclk = GpPClkGet();

/* Repair SDK timer - it forgets to set prescaler */
prescaler0 = (pclk/(8000*40))-1;
rTCFG0 = (rTCFG0&0xFFFFFF00)|prescaler0;
rTCFG1 = 0x30033;

/* Repair GpTickCountGet */
rTCNTB4 = pclk/1600;
}

 

[Blah]

Basically they're saying to count CPU ticks/cycles rather than use the RTC.
Arrghh, I don't like low-level stuff, thats why I like SDL.