You pair the pedal, the light goes solid, the phone lists it as connected. You open your charts in Safari, put your foot on it, and the page sits there. You press it again, harder, the way everyone does. Then you tab over to a news article, press it, and the article scrolls perfectly.
Here is what is happening.
A page-turner is a keyboard
Every Bluetooth page-turner sold for musicians presents itself to the phone as a HID keyboard. That is the whole of the device. It has one or two switches, and each switch sends a keystroke — usually Page Down and Page Up, or Down arrow and Up arrow, with a mode button to pick which pair. Some models add space or a letter key. There is no pedal protocol and no app to install; it’s a keyboard with two enormous keys.
That’s where the trouble starts, because keystrokes on iOS travel further than you’d expect before a web page hears them.
Where the keystroke stops
On iOS, the keystroke reaches Safari and goes no further. The page’s JavaScript is never told a key was pressed. This is a long-standing WebKit behaviour, not a bug in any particular site, and it holds for every mode the pedal offers.
It’s easy to verify and worth doing once. Open the same page in a desktop browser with a keyboard attached and every press of the pedal fires a keydown event the page can see. Open it on an iPhone or iPad and nothing arrives, in page mode or arrow mode.
The reason it feels intermittent — working on some pages, dead on others — is that WebKit still scrolls the page itself. On a long article, the scroll you see is Safari doing its own thing with the key, and the page was never involved. So the pedal looks like it works right up until you land on a page that needs to handle the key in code: a chart that scrolls by a measured amount, a set that steps to the next song, anything that isn’t a document being dragged upward.
Switching browsers doesn’t help: Chrome and Firefox on the iPhone are WebKit with a different icon, and inherit the same behaviour. Nor is there anything for a website to ask for — no permission prompt, no setting buried in Safari, no API for requesting raw key input. No website can work around this, and any site claiming to has quietly meant “we scroll like a normal document”.
Checking the pedal itself
Two minutes, and you’ll know where you stand. Pair the pedal with a laptop, open any text editor, and press it: the cursor jumps a page, or moves a line, depending on the mode. That’s the pedal sending exactly what it is supposed to send, and everything past that point is a software boundary. While you’re there, note which keys each mode sends and how to switch between them — usually a button held for three seconds.
What an app does instead
An app is on the other side of that boundary, and that is the whole of the difference. It isn’t asking a web page for anything, so the press arrives the way a press from any keyboard arrives, and the chart in front of you moves.
There is nothing clever underneath it and nothing to admire. The pedal is a keyboard, iOS and Android hand keyboard presses to the app in the foreground, and the chart scrolls. Nothing is installed, nothing is paired beyond the pedal itself, and there is no pedal setting anywhere in Chordisplay to find.
That is worth saying plainly, because the story reads like an engineering problem and it isn’t one. A browser tab is simply the wrong place to stand.
If you’re shopping for a pedal
None of this narrows the field much: check that it sends the page keys or the arrows, and that you can switch between them. What decides whether it works is on the other end — whether what you’re reading from is an app or a browser tab.