P3_0 for Output...

[lpcware]

Content originally posted in LPCWare by mubes on Wed Feb 03 08:13:52 MST 2016
OK, so this one is self-inflicted  8-)

I have laid a board that assumes an output is available on P3_0, just like it is on all its brothers and sisters. It's a very slow GPIO (<1Hz) and there's very little drive current required. Trouble is, NXP in their infinite wisdom didn't put a GPIO on that pin...and I didn't check.

I haven't quite reached the point where I need to actually deal with this problem yet, and I'm hoping I can address it by using the weak pullups and weak pulldowns until I roll a new board, but does anyone have any other bright ideas how to fix this one without hardware rework? I'd like these boards to be as 'close to final' as possible without visible rework on them if I can.

@NXP Guys....I don't suppose one of those 'Function reserved' for P3_0 happens to be a GPIO does it? Perhaps one that comes with caveats?

DAVE

[lpcware]

Content originally posted in LPCWare by mysepp on Thu Feb 04 04:38:54 MST 2016
Perhaps via SSP, Master Mode, Bit CPOL in Register CR0 (Table 976)???
But you must first setup/enable this peripheral.
Perhaps also high clock rate and 4 bit data size, so you get max 4 clocks when switching direction of your motor,
and finally it remains in the wanted state. But not tried, just an idea.
Perhaps this does not work at all...

[lpcware]

Content originally posted in LPCWare by mubes on Wed Feb 03 15:43:41 MST 2016
The pin is dedicated to I2S0 clocks with a secondary function of SSP0_SCK. I haven't done any experimentation yet but it's possible I can reduce a clock speed to zero to get the required effect; Would be really nice if there were a hidden GPIO function on that pin tho!

The pin is a direction bit for a motor so although it doesn't need to change quickly, but it does need to be stable.

Regards

DAVE

[lpcware]

Content originally posted in LPCWare by mysepp on Wed Feb 03 09:57:20 MST 2016
Check if you perhaps a supported peripheral on that pin delivers a static signal.
E.g. there seem to be CLK signals, perhaps you can enable the assigned peripheral and set idle clk level to low/high?
Is it just something like a LED or similar where e.g. some clk level changes do not matter/are not recognizable?

Or perhaps you can connect two pins together on the PCB, use P3_0 as input and drive it by the neighbour?
Looks afterwards like a not so good soldering...