This post is an FYI for others using the NXP LPC17xx Cortex M3 family. This may help you save some hair in your future development if you are to use the IAP Reinvoke ISP command 57.
I ran into a problem with the Reinvoke ISP command not functioning properly on while porting code from an existing LPC2103 project I relucantly inherited. Once into the ISP bootloader I could only reliably use the 'Read Device Signature' command in Flash Magic. Any other command would fail (I also tried the utility lpc21isp_179 with the same results).
After trying all I could think of it was time to contact NXP. Uncounted e-mails and a few days later after trying everything I could and NXP asked for (including sending my code to them to test with - they could not make it work with TeraTerm either), it was determined that in order to use the ISP Bootloader from code space requires that the HEAP to be setup with some non-zero value.
NXPs response was this:
"So it would help if you had some Heap space allocated !
When you enter ISP via the re-invoke ISP command it assumes you already have stack space setup. If you move your re-invoke ISP code up into main() it works fine as is, the reason for this is you forgot to allocate heap space in the startup_LPC17xx.s file. Or just allocate some heap space and you can leave the function as is."
Well, I tried this out (I set the value to 0x200)and Flash Magic worked repeatedly for all commands attempted.
Bottom Line: If you use uVision 4.00a and use the file startup_LPC17xx.s - DO NOT leave the declaration Heap_Size EQU 0x00000000 if you are going to use the IAP Reinvoke ISP command (unless you call it from within main() - according to NXP).
There is currently no documentation anywhere I searched on the web that contained this requirement with resonable search criteria entered.
Now there is....
Damn weekends. Cause you to think about work anyway...
In having time to think longer about NXPs response and asking myself why is there a requirement to have HEAP memory - it hit me.
If you use the 'out of the box' setups in the startup_LPC17xx.s file the stack was located (in my memory map) from 0x10000068 to 0x10000268. When I then added in some HEAP memory, the HEAP memory was then located to where the original stack space was. The stack (in my map file) location was relocated to then start at a RAM location around 0x10001700 or so.
In the LPC17xx Users Manual it states the following: "ISP commands use on-chip RAM from 0x1000 0118 to 0x1000 01FF. The user could use this area, but the contents may be lost upon reset."
This memory is: Right in the middle of the application stack space.
The tech support reps comment: "When you enter ISP via the re-invoke ISP command it assumes you already have stack space setup." means to me that when you enter ISP mode from application code (via command 57) it will use the current stack pointer (of the application) instead of the stack pointer it normally would use from a power up/reset.
If this is so, I believe this issue could now be corrected with the following variable attribute declaration in application code:
byte ISP_Reserved[0x1FF-0x118] __attribute__((at(0x10000118)));
Heap memory should then be allowed to be returned to 0 if not required.