Nxp semiconductors – NXP Semiconductors LPC24XX UM10237 User Manual
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UM10237_4
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User manual
Rev. 04 — 26 August 2009
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NXP Semiconductors
UM10237
Chapter 31: LPC24XX On-chip bootloader for flashless parts
Setting function pointer:
iap_entry=(IAP) IAP_LOCATION;
Whenever you wish to call IAP you could use the following statement.
iap_entry (command, result);
The IAP call could be simplified further by using the symbol definition file feature
supported by ARM Linker in ADS (ARM Developer Suite). You could also call the IAP
routine using assembly code.
The following symbol definitions can be used to link IAP routine and user application:
#
0x7fffff90 T rm_init_entry
0x7fffffa0 A rm_undef_handler
0x7fffffb0 A rm_prefetchabort_handler
0x7fffffc0 A rm_dataabort_handler
0x7fffffd0 A rm_irqhandler
0x7fffffe0 A rm_irqhandler2
0x7ffffff0 T iap_entry
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
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.
Table 643. IAP Command Summary
IAP Command
Command Code
Described in
Read Part ID
54
10
Read Boot code version
55
10
Compare
56
10
Reinvoke ISP
57
10