Functions
int	or1k_timer_init (unsigned int hz)

void	or1k_timer_set_period (uint32_t hz)

void	or1k_timer_set_handler (void(*handler)(void))

void	or1k_timer_set_mode (uint32_t mode)

void	or1k_timer_enable (void)

uint32_t	or1k_timer_disable (void)

void	or1k_timer_restore (uint32_t sr_tee)

void	or1k_timer_pause (void)

void	or1k_timer_reset (void)

unsigned long	or1k_timer_get_ticks (void)

void	or1k_timer_reset_ticks (void)

Detailed Description

The tick timer can be used for time measurement, operating system scheduling etc. By default it is initialized to continuously count the ticks of a certain period after calling or1k_timer_init(). The period can later be changed using or1k_timer_set_period().

The timer is controlled using or1k_timer_enable(), or1k_timer_disable(), or1k_timer_restore(), or1k_timer_pause(). After initialization it is required to enable the timer the first time using or1k_timer_enable(). or1k_timer_disable() only disables the tick timer interrupts, it does not disable the timer counting. If you plan to use a pair of or1k_timer_disable() and or1k_timer_enable() to protect sections of your code against interrupts you should use or1k_timer_disable() and or1k_timer_restore(), as it may be possible that the timer interrupt was not enabled before disabling it, enable would then start it unconditionally. or1k_timer_pause() pauses the counting.

In the default mode you can get the tick value using or1k_timer_get_ticks() and reset this value using or1k_timer_reset_ticks().

Example for using the default mode:

int main() {
  uint32_t ticks = 0;
  uint32_t timerstate;
  or1k_timer_init(100);
  or1k_timer_enable();
  while (1) {
    while (ticks == or1k_timer_get_ticks()) { }
    timerstate = or1k_timer_disable();
    // do something atomar
    or1k_timer_restore(timerstate);
    if (ticks == 100) {
      printf("A second elapsed\n");
      or1k_timer_reset_ticks();
      ticks = 0;
    }
  }
}

It is possible to change the mode of the tick timer using or1k_timer_set_mode(). Allowed values are the correct bit pattern (including the bit positions) for the TTMR register, it is recommended to use the macros defined in spr-defs.h. For example, implementing an operating system with scheduling decisions of varying duration favors the implementation of single run tick timer. Here, each quantum is started before leaving the operating system kernel. The counter can be restarted with or1k_timer_reset(). Example:

void tick_handler(void) {
  // Make schedule decision
  // and set new thread
  or1k_timer_reset();
  // End of exception, new thread will run
}
int main() {
  // Configure operating system and start threads..
  // Configure timer
  or1k_timer_init(50);
  or1k_timer_set_handler(&tick_handler);
  or1k_timer_set_mode(SPR_TTMR_SR);
  or1k_timer_enable();
  // Schedule first thread and die..
}

Function Documentation

uint32_t or1k_timer_disable ( void )

Disable timer interrupt

This disables the timer interrupt exception and returns the state of the interrupt exception enable flag before the call. This can be used with or1k_timer_restore() to implement sequences of code that are not allowed to be interrupted. Using or1k_timer_enable() will unconditionally enable the interrupt independent of the state before calling or1k_timer_disable(). For an example see Timer control.

Returns: Status of timer interrupt before call

void or1k_timer_enable ( void )

Enable timer interrupt

Enable the timer interrupt exception, independent of the status before. If you want to enable the timer conditionally, for example to implement a non-interruptible sequence of code, you should use or1k_timer_restore(). See the description of or1k_timer_disable() for more details.

The enable will also restore the mode if the timer was paused previously.

unsigned long or1k_timer_get_ticks ( void )

Get timer ticks

Get the global ticks of the default configuration. This will increment the tick counter according to the preconfigured period.

Returns: Current value of ticks

int or1k_timer_init ( unsigned int hz )

Initialize tick timer

This initializes the tick timer in default mode (see Timer control for details).

Parameters

hz	Initial period of the tick timer

Returns: 0 if successful, -1 if timer not present

void or1k_timer_pause ( void )

Pause timer counter

Pauses the counter of the tick timer. The counter will hold its current value and it can be started again with or1k_timer_enable() which will restore the configured mode.

void or1k_timer_reset ( void )

Reset timer counter

void or1k_timer_reset_ticks ( void )

Reset timer ticks

Resets the timer ticks in default configuration to 0.

void or1k_timer_restore ( uint32_t sr_tee )

Restore timer interrupt exception flag

Restores the timer interrupt exception flag as returned by or1k_timer_disable(). See the description of or1k_timer_disable() and Timer control for details and an example.

Parameters

sr_tee Status of timer interrupt

void or1k_timer_set_handler ( void(*)(void) handler )

Replace the timer interrupt handler

By default the tick timer is used to handle timer ticks. The user can replace this with an own handler for example when implementing an operating system.

Parameters

handler The callback function pointer to the handler

void or1k_timer_set_mode ( uint32_t mode )

Set timer mode

The timer has different modes (see architecture manual). The default is to automatically restart counting (SPR_TTMR_RT), others are single run (SPR_TTMR_SR) and continuous run (SPR_TTMR_CR).

Parameters

mode	a valid mode (use definitions from spr-defs.h as it is important that those are also at the correct position in the bit field!)

void or1k_timer_set_period ( uint32_t hz )

Set period of timer

Set the period of the timer to a value in Hz. The frequency from the board support package is used to determine the match value.

Functions

Detailed Description

Function Documentation