UM10375 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
User manual Rev. 3 — 14 June 2011 336 of 368
NXP Semiconductors
UM10375
Chapter 21: LPC13xx Flash memory programming firmware
21.14 IAP commands
For in application programming the IAP routine should be called with a word pointer in
register r0 pointing to memory (RAM) containing command code and parameters. Result
of the IAP command is returned in the result table pointed to by register r1. The user can
reuse the command table for result by passing the same pointer in registers r0 and r1. The
parameter table should be big enough to hold all the results in case the number of results
are more than number of parameters. Parameter passing is illustrated in the Figure 64
.
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.
The IAP function could be called in the following way using C.
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 long command[5];
unsigned long result[4];
or
unsigned long * command;
unsigned long * result;
command=(unsigned long *) 0x...
result= (unsigned long *) 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 function pointer:
iap_entry=(IAP) IAP_LOCATION;
Whenever you wish to call IAP you could use the following statement.
iap_entry (command, result);
As per the ARM specification (The ARM Thumb Procedure Call Standard SWS ESPC
0002 A-05) up to 4 parameters can be passed in the r0, r1, r2 and r3 registers
respectively. 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
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