Lpc2000

ee_gary wrote:

>Hi everybody,
>
>I'm wondering what is the best way to set and clear I/O bits without
>keeping track of what port they are on.  For example, something like:
>
>#define myOutput1 IO2PIN.1
>#define myOutput2 IO3PIN.28
>
>  
>
As per ANSI C, define a MACRO, For example:

============= begin ===============

typedef struct
{
  REG32 in0;                            // P0 Pin Value Register
  REG32 set0;                           // P0 Pin Output Set Register
  REG32 dir0;                           // P0 Pin Direction Register
  REG32 clr0;                           // P0 Pin Output Clear Register
  EG32 in1;                            // P1 Pin Value Register
  REG32 set1;                           // P1 Pin Output Set Register
  REG32 dir1;                           // P1 Pin Direction Register
  REG32 clr1;                           // P1 Pin Output Clear Register
  REG32 in2;                            // P2 Pin Value Register
  REG32 set2;                           // P2 Pin Output Set Register
  REG32 dir2;                           // P2 Pin Direction Register
  REG32 clr2;                           // P2 Pin Output Clear Register
  REG32 in3;                            // P3 Pin Value Register
  REG32 set3;                           // P3 Pin Output Set Register
  REG32 dir3;                           // P3 Pin Direction Register
  REG32 clr3;                           // P3 Pin Output Clear Register
} gpioRegs_t;

#define GPIO1            ((gpioRegs_t *)0xE0028000)

#ifndef BIT
#define BIT(n)              (1 << (n))
#endif

#define LED_EVENT_BIT      BIT(20)     // P1.20 output - low for EVENT LED.

#define IOPIN1           GPIO->in1       /* Pin Value Register */
#define IOSET1           GPIO->set1      /* Pin Output Set Register */
#define IODIR1           GPIO->dir1      /* Pin Direction Register */
#define IOCLR1           GPIO->clr1      /* Pin Output Clear Register */

============== THEN DO ====================

main () {
    IOCLR1 = LED_EVENT_BIT;
    IOSET1 = LED_EVENT_BIT;
}

============ OR ================

< the above defines>

static inline eventLedOff (void) { IOSET1 = LED_EVENT_BIT; }

static inline eventLedOn (void) { IOCLR1 = LED_EVENT_BIT; }

void main (void)
{
    eventLedOn ();
    eventLedOff ();
}

============  snip =====================


Making the function both static and inline will optimize (-O2 or -Os) 
into inline assembly rather than a function call.

There are no "bitwise" functions in gcc such as set_bit(LED_EVENT_BIT) 
or clear_bit(LED_EVENT_BIT), but you can write your own...


Regards,

TomW


-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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