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Altera_Forum
Honored Contributor I
1,252 Views

Timers

Hello, 

Im new to Nios. 

In my system there are 2 timers:timer_0 and timer_1. 

Defined as follow in system.h: 

 

/* 

* timer_0 configuration 

*/ 

 

 

#define 

TIMER_0_NAME "/dev/timer_0" 

#define 

 

TIMER_0_TYPE "altera_avalon_timer" 

#define 

 

TIMER_0_BASE 0x00042400 

#define 

 

TIMER_0_SPAN 32 

#define 

 

TIMER_0_IRQ 0 

#define 

 

TIMER_0_ALWAYS_RUN 0 

#define 

 

TIMER_0_FIXED_PERIOD 0 

#define 

 

TIMER_0_SNAPSHOT 1 

#define 

 

TIMER_0_PERIOD 1 

#define 

 

TIMER_0_PERIOD_UNITS "ms" 

#define 

 

TIMER_0_RESET_OUTPUT 0 

#define 

 

TIMER_0_TIMEOUT_PULSE_OUTPUT 0 

#define 

 

TIMER_0_LOAD_VALUE 24999 

#define 

 

TIMER_0_COUNTER_SIZE 32 

#define 

 

TIMER_0_MULT 0.0010 

#define 

 

TIMER_0_TICKS_PER_SEC 1000 

#define 

 

TIMER_0_FREQ 25000000 

#define 

 

ALT_MODULE_CLASS_timer_0 altera_avalon_timer 

 

/* 

* timer_1 configuration 

*/ 

 

#define 

 

TIMER_1_NAME "/dev/timer_1" 

#define 

 

TIMER_1_TYPE "altera_avalon_timer" 

#define 

 

TIMER_1_BASE 0x00042420 

#define 

 

TIMER_1_SPAN 32 

#define 

 

TIMER_1_IRQ 1 

#define 

 

TIMER_1_ALWAYS_RUN 0 

#define 

 

TIMER_1_FIXED_PERIOD 0 

#define 

 

TIMER_1_SNAPSHOT 1 

#define 

 

TIMER_1_PERIOD 100 

#define 

 

TIMER_1_PERIOD_UNITS "us" 

#define 

 

TIMER_1_RESET_OUTPUT 0 

#define 

 

TIMER_1_TIMEOUT_PULSE_OUTPUT 0 

#define 

 

TIMER_1_LOAD_VALUE 2499 

#define 

 

TIMER_1_COUNTER_SIZE 32 

#define 

 

TIMER_1_MULT "1.0E-6" 

#define 

 

TIMER_1_TICKS_PER_SEC 10000 

#define 

 

TIMER_1_FREQ 25000000 

#define ALT_MODULE_CLASS_timer_1 altera_avalon_timer 

 

 

 

What i want to know is:
  1. When i use the function : alt_alarm_start i see that the system automatically use timer_0 to set the alarm,why timer_0? 

  2. What should i do if i want the alarm every 100 micro seconds and still use the function : alt_alarm_start? 

 

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3 Replies
Altera_Forum
Honored Contributor I
51 Views

I think you may config your timer in sopc builder

Altera_Forum
Honored Contributor I
51 Views

and if want to use it in your nios, you may registry it first and then install it 

 

hope this will help
Altera_Forum
Honored Contributor I
51 Views

timer_0 must be defined as the system timer by default. You can change it to timer_1 by updating it in the bsp settings in NIOS SBT tool. 

 

The prototype for alarm start is: 

int alt_alarm_start 

( alt_alarm* alarm,  

alt_u32 nticks,  

alt_u32 (*callback) (void* context), 

void* context ) 

 

Think nticks is what you are looking for. You can use it to trigger a callback function after 100us systicks. One the callback is triggered, you can restart the same alarm within the callback itself.
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