When you have a look into the CY8CKIT-059 schematics you will see that there are some pins connected to caps. When you install the kit files you'll find all kit documentation in c:\Programs(x86)\Cypress.
I've looked at the docs --- do you have any more specific references?
I was hoping to get a sanity check from a human. Is this something other people have run into? Can they be turned on and off? Do I just need to pick different pins (which is tricky)? Are there ways to work around this?
BTW, based on about a 3K0 pullup resistor, 5V, and the curve shown in the second picture, I reckon the equivalent capacitance to be about 500nF. (Based on a completely random guess about the value of the internal pullup resistor.)
That seems like a lot for any internal capacitor --- aren't on-chip caps usually in the pF range?
There are capacitors on the board!!! It never even occurred to me to look there... at least that explains why there was no mention of them in the chip documentation.
(Also, if anyone from Cypress reads this: I was completely unable to find the CY8CKIT-059 documentation via PSoC Creator. There appears to be no top-level documentation index? I can get to datasheets for components easily enough, but anything else is unfindable. And searching for "cy8ckit-059" inside the Technical Documentation section of the Cypress website doesn't produce anything. I eventually found it by searching for "cy8ckit-059" in the site-wide search box. This could definitely be improved.)
It looks like only P0 has the capacitor --- P0[5-7] don't. That explains what I'm seeing. And the value stated is 1uF, which is less than one order of magnitude out from my estimate, which is nice.
There's no way to eliminate this in software, isn't there? There's only about a paragraph in the documentation, but the circuit diagram suggests it's hard-coded. My physical layout is constrained so I may need to be creative.
Why not take the cap off the board? If you aren't using SAR0 you don't need it.
I keep a list of the 7 pins with caps on the board because I was gettnig caught with this all the time.
That's what I did in the end, actually. But I don't like modifying the board --- I don't have the equipment to cleanly remove SMD components, and I don't want to risk lifting a track or damaging the board. (Plus, it's a bit antisocial to ask other people to do it to try my stuff.)