1778 NVIC Undocumented IRQ

[lpcware]

Content originally posted in LPCWare by MikeSimmonds on Mon Sep 24 12:05:11 MST 2012
[FONT=Tahoma][SIZE=2]Investigation on a 1778 device (LQFP-208) has revealed that the NVIC implements 42 IRQs. :eek:

This is easily verified: write -1 to the first 2 'set pending' registers, read them back
[I get FFFFFFFF and 3FF], count the '1' bits.

It would be prudent to diasble these interrupts first; w[/SIZE][/FONT][FONT=Tahoma][SIZE=2]rite -1 to the first 2 'clear enable'
registers[/SIZE][/FONT][FONT=Tahoma][SIZE=2].
[/SIZE][/FONT][FONT=Tahoma][SIZE=2]
Only 41 are documented: Watchdog to EEPROM.

Does anyone know what the extra one is for, and if it would be safe
to use it as a software triggered interrupt?

Cheers, Mike[/SIZE][/FONT][FONT=Tahoma][SIZE=2]
[/SIZE][/FONT]

[lpcware]

Content originally posted in LPCWare by frame on Tue Sep 25 02:37:27 MST 2012
I would suspect them belonging to peripheral units that the lpc1778 dos not have,
but other members of the family, like the 178x.

It would be plausible to use as much of the same silicon for the family as possible,
and include the "reserved bits, don't touch" warning in the manuals.
As this could change from one silicon revision to the next, I would refrain from
making use of this in any commercially sold software...[IMG]http://knowledgebase.nxp.com/images/icons/icon7.gif[/IMG]

I don't have any lpc1778, nor a 178x, so it's just a guess.