I just saw this bug while searching the web. I haven't been able to get a Pico 2 so I bought a Seeed Xiao RP2350 board which I just received yesterday. Maybe it's a good thing that these boards have not been more available...
Here is the errata excerpt from the rp2350 datasheet
At least this bug is documented. I haven't powered my board yet so I have not had a chance to encounter the problem.
Here is a link to a post on Hackster - Hardware Bug in RP2350 leads to unexpected pull-down behavior.
A simple test, drive an IO pad with a source impedance of 10 kOhms
With the Input buffer disabled and Pull Up/Down Disabled
mem32[0x40038000+4]=0x000
The IO pad doesn't load the 10kOhm source, as it should Ie being high-impedance.
With the Input buffer enabled and Pull Up/Down Disabled
mem32[0x40038000+4]=0x040
The IO pad is sourcing and sinking current and loading the source resistance.
As a high impedance input it should not source or sink ANY current.
They didn't do a great job explaining the issue. The issue is the input buffer sources current into the IO pin, so the electrical characteristics table is wrong.
The pin latches in pull-down mode because this input buffer sources more current than the pull-down resistor can sink.
The leakage of the input buffer looks something like the following.
The built-in pulldown resistors are strong enough to overdrive this weird input buffer, so one could also just add their own 10K pull-down resistor on board.
They didn't do a great job explaining the issue. The issue is the input buffer sources current into the IO pin, so the electrical characteristics table is wrong.
The pin latches in pull-down mode because this input buffer sources more current than the pull-down resistor can sink.
The leakage of the input buffer looks something like the following.
The built-in pulldown resistors are strong enough to overdrive this weird input buffer, so one could also just add their own 10K pull-down resistor on board.
