CCS/MSP430F5529: setting timer

The FreeRTOS source has a sample vApplicationSetupTimerInterrupt() function in:

FreeRTOS\Demo\MSP430X_MSP430F5438_CCS\Demo_Source\main.c

It uses TA0, and gets (roughly) 1ms tick from ACLK, which runs at 32.786 kHz. I think it should be fine for the F5529.  FreeRTOSConfig.h will also need 

> #define configTICK_VECTOR TIMER0_A0_VECTOR

Since 32768 isn't evenly divisible by 1000, this doesn't provide a high-accuracy clock (off by 2%). However, ACLK runs in LPM3 which may be a useful tradeoff in many applications.

[Edit: Actually since there's no "-1" it's effectively rounding up, so the clock is only off by about 0.7% (=(32+1)*1000/32768).]

Hi Toda, Hope the previous E2E discussion is helpful on your problem. May I know if you have more question on MSP430F5529?

Thank you, Sir.

That is all. Thank you!

Hi Toda, Thanks for your confirmation!

Actually, I have one question more. I am using  int = xTaskGetTickCount() function. It works fine, but after some point it returns negative value. 

Can you tell me what should be a problem here?

BR,

Ana

1) Declare your variable as TickType_t, not int. xTaskGetTickCount is defined to return a TickType_t which is either a uint16_t or a uint32_t [*], in either case unsigned, not (signed) int. 

2) Even as an unsigned, the returned value will eventually wrap back to 0. Organize your usage around differences between values, not actual values.

[*] (depending on configUSE_16_BIT_TICKS in FreeRTOSconfig.h)

What is the maximum value after it wrap back to zero?

I am trying to write function to get second and minutes if one tick is 1ms. Something like this.

void gettime() {
uint16_t counter=0;

uint16_t m,s;

//if (tik>=65000) counter=counter+1; if thats the max value

//s=tik/1000 +counter*65000;
s=tik/1000

if (s>=60)
m =s/60;
else
m=0;

s=s-m*60;

}

And another question, if I may ask. How can i convert s and m into string. How can I use sprintf for uint32?

Thank you,

Ana

Assuming you've got configUSE_16_BIT_TICKS=0, that's 2^32 ms, which my calculator says is about 49.7 days. (I've seen it happen.)

To use snprintf (avoid sprintf) on a uint32_t, use "%lu". As I recall you need to set CCS "Build Options->Compiler->Advanced->Language->Level of printf" to "nofloat" to get "%lu".

[Edit: Mispelled "uint32_t" the first time.]