limit_switch.c File Reference

Software limit switches. More...

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Defines
#define	LS_NUM_SWITCHES   (10)
	The maximum number of limit switches.
Functions
LS_STATE	ls_get_state (int id)
	Returns the state of the switch with the given id.
int	ls_init_switch (unsigned int new_limit, INT_VOID_F funct)
	Initializes a limit switch with the given limit and signal function.
void	ls_update (void)
	Updates the state for every limit switch.
Variables
int	ls_count = 0
	The number of limit switches currently being used.
LIMIT_SWITCH	ls_switches [LS_NUM_SWITCHES]
	The array of limit switches.

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Detailed Description

Software limit switches.

A limit switch will wait for a given limit of consecutive high signals before turning high, and the same for turning low again. If a low signal interrupts a stream of high signals (or vice versa), the counter is reset.

Example pin setup for Limit Switch (used by ankle controllers):

  // *******************************************************************************
  // Limit Switch Setup                                            
  // *******************************************************************************  
  PINSEL0 &= ~(3<<0); //set P0.0 to GPIO
  PINSEL0 &= ~(3<<2); //set P0.1 to GPIO
  FIO0DIR &= ~(1<<0); //set P0.0 to input
  FIO0DIR &= ~(1<<1); //set P0.1 to input

Author:

Nicolas Williamson

Date:

July 2009

Definition in file limit_switch.c.

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Define Documentation

#define LS_NUM_SWITCHES   (10)

The maximum number of limit switches.

Definition at line 28 of file limit_switch.c.

Referenced by ls_init_switch().

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Function Documentation

LS_STATE ls_get_state

(

int

id

)

Returns the state of the switch with the given id.

The id of the switch was set by the ls_init_switch function. The id is also the index of the switch within the array of switches, so it begins at 0 for the first switch, and increments with each switch that is initialized.

Parameters:

id

The id of the switch.

Returns:

The output state of the switch.

Definition at line 97 of file limit_switch.c.

References error_occurred(), ls_switches, and LIMIT_SWITCH::state.

{
  if (id < ls_count && id >= 0){
    LIMIT_SWITCH* ls = &(ls_switches[id]);
    return ls->state;
  } else {
    error_occurred(ERROR_LS_INVALID_ID);
    return LS_OFF;
  }
}

int ls_init_switch	(	unsigned int	new_limit,
		INT_VOID_F	funct
	)

Initializes a limit switch with the given limit and signal function.

Call this function from software_setup for each limit switch.

Parameters:

	new_limit	The limit of consecutive signals needed before output changes.
	funct	A signal functino which returns 0 for low and non-zero for high.

Returns:

The id of the limit switch, or -1 if the switch failed to initialize.

Definition at line 40 of file limit_switch.c.

References LIMIT_SWITCH::count, error_occurred(), LIMIT_SWITCH::function, LIMIT_SWITCH::limit, ls_count, LS_NUM_SWITCHES, ls_switches, LIMIT_SWITCH::prev, and LIMIT_SWITCH::state.

{
  if (ls_count < LS_NUM_SWITCHES){
    int id = ls_count;
    LIMIT_SWITCH* ls = &(ls_switches[ls_count++]);
    ls->limit = new_limit;
    ls->function = funct;
    ls->count = 0;
    ls->prev = LS_OFF;
    ls->state = LS_OFF;
    return id;
  } else {
    error_occurred(ERROR_LS_NUM_SWITCH);
    return -1;
  }
}

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Variable Documentation

int ls_count = 0

The number of limit switches currently being used.

Definition at line 31 of file limit_switch.c.

Referenced by ls_init_switch(), and ls_update().

LIMIT_SWITCH ls_switches[LS_NUM_SWITCHES]

The array of limit switches.

Definition at line 30 of file limit_switch.c.

Referenced by ls_get_state(), ls_init_switch(), and ls_update().