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User manual Rev. 12.3 — 10 June 2014 439 of 547

NXP Semiconductors

UM10398

Chapter 26: LPC111x/LPC11Cxx Flash programming firmware

are more than number of parameters. Parameter passing is illustrated in the Figure 92.

The number of parameters and results vary according to the IAP command. The

maximum number of parameters is 5, passed to the "Copy RAM to FLASH" command.

The maximum number of results is 4, returned by the "ReadUID" command. The

command handler sends the status code INVALID_COMMAND when an undefined

command is received. The IAP routine resides at 0x1FFF 1FF0 location and it is thumb

code.

Call the IAP function in the following way:

Define the IAP location entry point. Since the 0th bit of the IAP location is set there will be

a change to Thumb instruction set when the program counter branches to this address.

#define IAP_LOCATION 0x1fff1ff1

Define data structure or pointers to pass IAP command table and result table to the IAP

function:

unsigned int command_param[5];

unsigned int status_result[4];

unsigned int * command_param;

unsigned int * status_result;

command_param = (unsigned int *) 0x...

status_result =(unsigned int *) 0x...

Define pointer to function type, which takes two parameters and returns void. Note the IAP

returns the result with the base address of the table residing in R1.

typedef void (*IAP)(unsigned int [],unsigned int[]);

IAP iap_entry;

Setting the function pointer:

iap_entry=(IAP) IAP_LOCATION;

To call the IAP, use the following statement.

iap_entry (command_param,status_result);

Up to 4 parameters can be passed in the r0, r1, r2 and r3 registers respectively (see the

ARM Thumb Procedure Call Standard SWS ESPC 0002 A-05). Additional parameters are

passed on the stack. Up to 4 parameters can be returned in the r0, r1, r2 and r3 registers

respectively. Additional parameters are returned indirectly via memory. Some of the IAP

calls require more than 4 parameters. If the ARM suggested scheme is used for the

parameter passing/returning then it might create problems due to difference in the C

compiler implementation from different vendors. The suggested parameter passing

scheme reduces such risk.

The flash memory is not accessible during a write or erase operation. IAP commands,

which results in a flash write/erase operation, use 32 bytes of space in the top portion of

the on-chip RAM for execution. The user program should not be use this space if IAP flash

programming is permitted in the application.