liblpc2000_iap_command documenation?

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LPC_noob

• May 24, 2011 09:16

HI,

 

I'm trying to use the liblpc2000_iap_command function to update application code, unfortunately I can't find any documentation on this function?

I've done some testing and it looks like it's not a good idea to disable interrupts before calling this function.

 

/*------------------------------------------------------------------------------------*/
/*         No interrupt disabling before calling liblpc2000_iap_command               */
/*------------------------------------------------------------------------------------*/

unsigned long result ;

liblpc2000_iap_command ( IAP_CMD_READ_PART_ID, 0, 0, 0, 0, &result ) ;

printf ( "Part ID %x", result )

 

Produces

Part ID = 4FF11 (correct)

 

/*------------------------------------------------------------------------------------*/
/*            Disabling interrupt before calling liblpc2000_iap_command               */
/*------------------------------------------------------------------------------------*/
unsigned long result ;

libarm_isr_disable_irq ( ) ;
liblpc2000_iap_command ( IAP_CMD_READ_PART_ID, 0, 0, 0, 0, &result ) ;
libarm_isr_enable_irq ( ) ;

printf ( "Part ID %x", result )

 

Produces

Part ID = 1c200 (wrong)

 

Is there anything else I should be aware of when using this function or should I implement this function myself (more portable, no worries about black box undocumented functions)?

0

• 

  Jon Elliott

  • May 24, 2011 14:37

  There are a some words in the liblpc1000.h header file describing the liblpc2000_iap_command function - there isn't much too it, here is the implementation:

  #include "liblpc2000.h"
  
  #define IAP_LOCATION 0x7FFFFFF1
  
  typedef void (*IAP)(unsigned long [], unsigned long[]);
  
  unsigned long
  liblpc2000_iap_command(unsigned long cmd, unsigned long p0, unsigned long p1, unsigned long p2, unsigned long p3, unsigned long *r0)
  {
    unsigned long command[5] = {cmd, p0, p1, p2, p3};
    unsigned long result[2];
    ((IAP)IAP_LOCATION)(command, result);
    if (r0)
      *r0 = result[1];
    return result[0];
  }

  I think the problem you are observing is because you are using libarm_isr_enable_irq and libarm_isr_disable_irq rather than libarm_enable_irq and libarm_disable_irq - the former functions are used for re-enabling interrupts from within an ISR and change the processor mode (and therefore the current stack).

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